Know Your Natives – Dwarf Larkspur

Dwarf larkspur (Delphinium tricorne) of the Buttercup (Ranunculaceae) family has distinctive early spring flowers that are often dark bluish-purple (or sometimes white).  Other common names include spring larkspur and rock larkspur.  This species is typically found in rich alluvial deciduous woods and wooded rocky slopes in shady to partially sunny sites with dry to mesic soils.  It is found in the U.S. from Nebraska to Pennsylvania and from Oklahoma to Georgia.  In Arkansas, it is found primarily in the Interior Highlands of the northwestern half of the state, with scattered occurrences in better drained sites of the Mississippi Alluvial Plain.  The genus name “Delphinium” comes from a Greek word for “dolphin” based on the shape of flower spurs and buds as viewed from the side.  The specific epithet refers to the horn shape of the three follicles that constitute the fruit.

This herbaceous perennial has an ephemeral nature in that it has new basal growth in mid-winter, blooms in early to mid-spring and then goes dormant in late-spring.  Roots are elongate, shallow and branched pointy tubers with long fibrous roots.  The upper ends of the tubers have growth points from which open clusters of basal leaves and weakly erect flowering stems (peduncles) grow.  Stems, in early spring, are straight and puberulent (covered with almost imperceptible downy hairs).  Cauline leaves, on stems up to 2 feet tall, are limited to a few alternate leaves along the lower portion of stems.  The uppermost of these few cauline leaves subtend single flowers while higher up single flowers are subtended by narrow, linear, pointed bracts that decrease in size up-stem.

Basal leaves that first appear in mid-winter and those basal leaves that grow later have the same appearance, and the cauline leaves, too, are similar, although these leaves may be smaller.  Basal and cauline leaves, which remain vibrant throughout the bloom period, have an overall orbicular shape that is palmately compound (trifoliate).  The three leaflets are then deeply incised to form wedge-shaped lobes which in turn are futher deeply cut.  The central leaflet of a leaf tends to be incised into three lobes and the two lateral leaflets tend to be incised into two lobes.  The leaf blade may appear to be five-lobed.  Smooth margins of all lobes are interrupted by additional minor lobing.

Mid-winter leaves have reddish, flat-topped and pubescent petioles and leaf blades have ciliate margins and pubescent undersides.  Petioles of mature basal leaves are about ¾ inch long, slender, medium green and slightly pubescent.  Mature leaf blades are several inches across and mostly glabrous.*

Dwarf Larkspur - Delphinium tricornePhoto 1:  In mid-winter, basal leaves unfurl.  Note pubescence of petioles and leaf blades.

Dwarf Larkspur - Delphinium tricornePhoto 2:  Appearance of trifoliate basal and cauline leaves are similar.  Early pubescence is lost as the season progresses.  Photo taken at end of March.

Pedicels (stalks of individual flowers) grow upward from the peduncle in raceme fashion at about 45 degrees.  Racemes, to about 8 inches long, have up to about 25 loosely arranged flowers.  Peduncles and pedicels tend to be densely covered with short pubescence, which falls off with age.  Light green flower buds on long pedicels are round in cross-section and stubby.  Flower buds have an exterior that features flattened, indented faces with five rounded bumps and a backward projecting spur.  Flowers typically have dark bluish-purple sepals and petals, although lavender to white flowers may occur and the upper two petals of dark blue flowers may be whitish.  Sepals, the most prominent part of the flower, are broad and petal-like with a gently tapered tip.  Sepals have an indented area near their apices that corresponds to the bumps that were present on the bud’s face.  Along with the upper sepal, which bears the long upward-angled, backward-pointing tubular spur, two sepals are opposite the flower’s center and two lower sepals are down-angled to either side.  The spur contains nectar that is pilfered by bumblebees by cutting into the spur and legitimately taken by smaller bees that enter from the front and typically effect pollination.  At anthesis, the corolla faces slightly downward, and the backward projecting spur is angled upward at about 90 degrees to the pedicels.  The soft half-inch-long spurs have a diameter that gradually decreases to a blunt tip.  Flowers have small round calices with a small elongate bract at each side.

In addition to the prominent sepals, flowers, up to 1 inch across and 1½ inches long, have two upper petals, two lower petals, a group of stamens and three pistils.  The two upper petals, which may be whitish or the same color as the sepals, are upward flared and overlapping.  The two lower petals, same color as sepals, are larger than the upper two petals, lobed and down-flared with numerous whitish, tangled hairs on their outer surface.  Stamens, grouped behind the lower petals (when viewed from front of flower) have whitish filaments and black dangling anthers.

Dwarf Larkspur - Delphinium tricornePhoto 3:  Flower buds, as seen at left as well as in right foreground, suggest the shape of a dolphin, the source of the genus name Delphinium.  Sepals and petals of this particular plant are all the same color.  Stamens can be seen behind the two lower hairy petals.

Dwarf Larkspur - Delphinium tricornePhoto 4:  Trifoliate leaves have many elongate, broad lobes with rounded apices.  Basal leaves remain vibrant throughout the growing season.  Photo taken in early April.

With fertilization, the three ovaries produce three free-standing, bean-pod-like follicles that are joined at their bases.  The half-inch-long glabrous follicles, with long pointed beaks, arch backward away from their common center, with sutures bowed-up.  When mature and dry in mid-spring, follicles split along sutures and small, black, smooth seeds are released.  With the fruiting cycle completed about late May, plants quickly return to dormancy.

Dwarf Larkspur - Delphinium tricornePhoto 5:  In early May, follicles are beginning to dry.  Trifoliate upper leaves exhibit relatively little lobing.

*Another widespread larkspur in Arkansas is Carolina larkspur (Delphinium carolinianum), with three subspecies in the state.  It also typically has dark blue or white flowers, but flower stems are up to 4 feet tall and plants are found in sunnier, drier sites.  In mid-winter, the basal leaves of the most common and widespread variety of D. carolinianum, var. carolinianum, and D. tricorne can be easily confused, both being trifoliate and similarly lobed.  However, in the case of D. carolinianum var. carolinianum, lobes of its later leaves become increasingly narrow and numerous.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Ohio Buckeye

Ohio Buckeye (Aesculus glabra) of the Soapberry (Sapindaceae) Family, formerly of the Horsechestnut (Hippocastanaceae) family, is a medium to large deciduous tree with opposite, palmately compound leaves.  It is native from central Texas to western Pennsylvania and as far north as central Iowa to southern Michigan and south into northern Alabama and the highlands of the northwestern half of Arkansas.  Other common names include “American buckeye” and “fetid buckeye”, based on the odor of crushed leaves, bark and twigs.  The name “buckeye” relates to the dark, ovoid poisonous seeds that have a lighter colored hilum (scar).

Ohio buckeye, with long taproots bearing lateral roots, typically occurs in rich, well-drained soils in sheltered areas of valleys, ravines and slopes in partial to full sunlight.  In shady drier sites, it tends to remain more shrub-like and may reach 15 feet in height, while in sunny favorable sites in Arkansas, it may be 40 feet*.  Trunk diameter remains relatively small at up to about 2 feet.  Large trees in sunny sites have numerous lateral branches that produce a broad rounded crown.  Lower lateral branches are lost in shady sites.  Plants as young as three years old can produce flowers.

Ohio Buckeye - Aesculus glabraPhoto 1:  This 4-inch seedling, in late January, would already have a long taproot.  Seeds in inset were similarly planted outdoors, but had not yet sprouted.

In winter, Ohio buckeye has round tapered lateral or axillary buds with sharp points that grow from just above previous year’s leaf scars. Terminal buds also form on nonflowering shoots.  Buds are covered with six or so layers of tightly imbricated scales with pointed tips.  Scales may have free-standing tips and are slightly keeled at their center.  Most new growth is from the uppermost lateral buds–the terminal inflorescence is shed in the fall or winter, leaving no true terminal bud on the original stem–as well as from terminal buds on sterile stems.   Many lateral buds do not develop. Because the terminal inflorescence is shed after seed dispersal, the dominance of the uppermost lateral buds gives the buckeye crown a very jagged architecture, which is best seen in winter.

In mid to late winter, the most-exterior scales just drop off while inner scales become light green and grow into long, leaf-like appendages before they, too, drop off.  By the time flowers reach anthesis, bud scales are gone and stem growth for the year has mostly stopped.

New stem growth is green and finely pubescent and becomes light gray and glabrous later in the year.  Previous years’ stems bear large, shield-shaped scars where leaves from previous years have dropped off.  Older branches are smooth and gray while larger trees have bark that has small scaly to knotty, unfurrowed plates that uniformly cover the trunk.

When new leaves first unfurl, the opposite leaves are a golden green which evolves to a pale green at time of bloom and a shiny, dark green upper surface in summer while the lower surface is a lighter green.  Leaves, glabrous on upper and lower surfaces, typically have five spreading leaflets, all attached at the tip of the petiole or leaf stalk (palmate), but three leaves and seven leaves may occur.  Leaves have slender, glabrous and light green petioles up to 6 inches long, with a broad clasping base and leaflets that are 3 to 6 inches long.  The central leaflet is the largest and, along with the next two lower leaflets, is at its broadest 1- to 2-inch-width in its upper portion with a gentle taper to its nearly stalkless base and a sharp taper to its apex (somewhat obovate).  The lower two broadly lanceolate leaflets are angled downward within the plane of the leaf.  While the lower portions of leaflets have entire margins, the upper portions have crenulated margins with tiny teeth.  In fall, leaves may become a showy reddish-orange.  Venation of the leaflets is pinnate with straight, equally spaced opposite or offset veins.

New terminal growth of more vigorous stems continues unabated to produce an upright panicle of flowers 6 to 8 inches long.  The peduncle of the inflorescence begins immediately above the last set of new leaves, initially with the same appearance as the stem below.  Above the peduncle, groups of flowers are spread around the rachis with spaces between groups.  Stalks of the floral groups are initially coiled against the rachis, but as growth continues, flower buds enlarge and open and the coils gradually straighten.  Flowers all along the rachis open in unison from the rachis to the ends of the straightened coils. Flowering continues for several weeks.  At the time of bloom, the color of the stem, peduncle, rachis and pedicel are the same light green with very short pubescence.  New stems and rachises become tan with rounded white lenticels (pores) by mid-summer.  Peduncles fall off after seeds mature and the capsules split open.

Ohio Buckeye - Aesculus glabraPhoto 2:  Terminal and lateral buds produce rapid spring growth.  These two stems grew from separate lateral buds at the top of previous year’s growth.

Ohio Buckeye - Aesculus glabraPhoto 3:  This plant, only several years old, produced its first inflorescence.  Note enlarged reddish bud scales about to fall off and (on the trunk) leaf scars, undeveloped buds and lenticels.

Ohio Buckeye - Aesculus glabraPhoto 4:  Opposite leaves typically have five leaflets with pinnate venation and crenulated margins.  Note axillary leaf buds for next years’ growth.

The inch-long greenish yellow flowers, on short pedicels, tend to be mostly male (staminate) with perfect (bisexual) flowers near the base of the cluster.  Flowers have greenish yellow, round and slightly elongated calyxes with five rounded lobes enclosing four greenish yellow petals.  The length of petals protruding from the calyx is greater than the length of the calyx itself.  Two long petals, that are flared upward, may bear orange, feather-like markings extending from flower’s throat to near the petals’ ends.  Two shorter broader petals flare outward in near-horizontal fashion.  Ends of the four petals are roundly flexed toward the flower center.  Flowers have seven stamens with white filaments and brown anthers that are exserted beyond the corolla, and a white pointed pistil (in perfect flowers only) equally exserted beyond the corolla.  The pistil of a flower becomes fully exserted (with open stigma) before the corolla has opened and before stamens are exserted.  Pistils are covered with a fine pubescence while filaments and the exterior of petals have longer hairs.

Ohio Buckeye - Aesculus glabraPhoto 5:  Flowers that are positioned along the upper sides of the clusters.   Pistil of a flower is exserted before flower’s stamens appear, as seen at lower left.

Ovaries of fertilized perfect flowers form green, round, spiky fruits.  Typically, only a few fruits at the base of the panicle will reach maturity.  Mature fruit is an ovoid, thick-skinned and light brown leathery capsule.  The capsule, up 1-½ inches in diameter, contains one to three seeds in separate chambers.  By the time fruit has matured, with multiple seeds, the seed exterior becomes flattened due to seed-to-seed contact.  At dehiscence (splitting of fruit) in late summer, capsules with sharp prickles split, so that the smooth, shiny mahogany-colored seeds with a light tan hilum, drop out.  Seeds, 1 to 1-½ inch wide and long, may germinate where dropped or wherever buried by squirrels or deposited by flowing water.  Seeds can germinate in mid-winter.  With germination, taproot and leaves quickly become fully functional so that cotyledons are not needed for photosynthesis.

Ohio Buckeye - Aesculus glabraPhoto 6:  Fertilized ovaries develop into fruit with long, weak spines.  Typically, only a few fruits per panicle will reach maturity.  Photo in mid-April.

Ohio Buckeye - Aesculus glabraPhoto 7:  Upper portion of panicle beyond developing fruit has dropped off in this mid-July photo.  Note two opposite brown buds at base of panicle’s peduncle (for next year’s growth).

Ohio buckeye can be a desirable garden or wildland plant where people, pets or livestock would not consume the seriously poisonous (contains aesculin) seed or other plant parts (squirrels apparently are not affected).   The plant is quite ornamental with its large attractive leaves, showy flowers and interesting fruit.  It has full-size flower panicles and fruit within several years of being planted by seed.  It also has nice fall color.  It does best in a mesic (moderately and evenly moist) soil where is protected from strong sun and wind.  Leaves may drop early in response to dry, hot conditions.

Red buckeye (Aesculus pavia) is the only other species of the genus native to Arkansas.  Red buckeye, occurring across most of the state, is more shrub-like, with red flowers and smooth seed capsules.  Native to the Appalachians and sometimes cultivated, yellow or big buckeye (Aesculus flava) is dissimilar to Ohio buckeye in various ways, including 1) its lower leaflets extending horizontally, 2) pistil and stamens that are not exserted, 3) fruit capsules that are smooth, and 4) typical height at maturity of 70-90 feet.  Bottlebrush buckeye (Aesculus parviflora) is a species native to the Southeast U.S., primarily Alabama, that is also frequently cultivated.  It differs from Ohio buckeye in having a definite shrubby habit, with multiple stems and suckers from the base, and longer panicles of white flowers with long-exserted filaments.

*  National champion Ohio buckeye in Casey County, KY, is 148 feet tall.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Arkansas Yucca

Arkansas yucca (Yucca arkansana) of the Agave (Agavaceae) family, formerly of the Lily (Liliaceae) family, an evergreen shrub, occurs in Texas, Oklahoma, southeastern Kansas, southern Missouri and Arkansas.  In Arkansas, it occurs throughout much of the Interior Highlands.  The genus name originates from a misapplication by Carl Linnaeus in 1753 of a common name for cassava (Manihot esculenta), “yuca”, to the plants for which he named and described the genus Yucca.  Arkansas yucca, also called soft-leaf yucca and soapweed, is found in well-drained soils in sunny prairies, glades and rocky hillsides as well as along partially sunny edges of woodlands and thickets.

A mature Arkansas yucca has a several-feet-long taproot-like rhizome (round in cross-section) along with near-surface, short lateral side-rhizomes with scattered fibrous roots.  Rhizomes, that may be one or more inches in diameter, have a brown epidermis with a white potato-like interior.  Ends of lateral rhizomes turn toward the surface, where apical buds each produce a single rosette of leaves.  A mature plant may have a half-dozen scattered leaf rosettes so that a single plant appears to be a colony.  Single, stout, woody flower stalks grow from the apical bud within leaf rosettes.  After flowering, those rosettes and their rhizome segment die and decay, leaving a circular scar or nub on the surviving portion of the root.

Arkansas Yucca - Yucca arkansanaPhoto 1:  Rhizome segment at coin is decaying after producing a flower stalk marked with a red asterisk.   Lateral roots grew from either side of dead segment.  Taproot is below coin.

Leathery, flexible, radiating leaves, up to about 2 feet long, are widest at mid-leaf with a width of about ¾ inch.  Reduction of leaf width towards its pointed, pliable tip is very gradual.  White-edged margins are straight and entire with scattered, long, loosely curly white filaments that exfoliate from margins.  Leaves, a dull medium green above and below, become narrow near their bases before finally widening within the rosette base.  Leaves are convex below and concave above, with a thickened stout midrib.  Toward mid-leaf, the blade gradually widens and the midrib becomes less prominent and less stout where leaf may bend down and become twisted.  Parallel venation is not prominent on the upper or lower leaf surfaces.  Bases of previous years’ leaves gradually weaken so that old leaves gradually lower to lie on the ground where they remain for several years, gradually decaying.  Plants are usually stemless (acaulescent), although a short leaning (decumbent) stem, mostly hidden by decaying leaves, may develop.   Leaf rosettes may be 2 feet tall and wide.

Arkansas Yucca - Yucca arkansanaPhoto 2:  Long, radiating leaves are thin and pliable with a flexible point.  Photo taken in late February.

Arkansas Yucca - Yucca arkansanaPhoto 3:  Curly marginal hairs are not twisted as on some other species.  Appreciable stems do not develop as leaf rosettes add new central leaves from year to year.

The inflorescence in early spring consists of a raceme on a tall, stiffly erect, somewhat woody and glabrous stalk (rachis) that grows from the apex of a leaf rosette.  Stalks, usually 2 to 3 feet tall (but may reach 6 feet), have narrow, triangular and purplish bracts that are erect, both below and within the raceme.  As erect flower buds on the upper portion of the stalk enlarge behind bracts, those bracts wither and the pedicels bend down at the base of flowers so that, at anthesis, flowers droop and face the ground.  Individual flowers are on short pedicels (attached directly to the stalk) or in a group of several flowers (small panicles) on short pedicels growing from a short peduncle (which, in turn, is attached to the stalk).   Individual plants typically do not bloom every year.

Arkansas Yucca - Yucca arkansanaPhoto 4:  In this early May photo, purplish bracts on elongating flower stalk subtend and cover developing flower buds.  Bracts are relatively short, as compared to other species.

Arkansas Yucca - Yucca arkansanaPhoto 5:  Flowers, on short pedicels and peduncles, occur in a raceme-type inflorescence.  Bracts on the lower portion of the stalk do not dry while flowers are in bloom.  Site shown is mostly shady with loam soil.

The bell-shaped (campanulate) flowers, up to 2½ inch long and 2 inches wide, have six greenish-white, thickened tepals (three sepals and three petals) that have narrow bases, gentle tips and broadened mid-sections.  The whitish green superior ovary is topped by a pale green lobed style that terminates in a three-lobed stigma with a recessed central orifice.  Six round, white, post-like filaments, attached to flower receptacle below the ovary, bear pollinia (packets of pollen) at their rounded apices.  Yucca moths are the only insects that can successfully pollinate yucca flowers and developing yucca fruit is the only larval food source for yucca moths.*

Arkansas Yucca - Yucca arkansanaPhoto 6:  Heavy flowers cause pedicels to bend down.  As seed capsules develop, strengthened pedicels bend upward.

Arkansas Yucca - Yucca arkansanaPhoto 7:  The lobed green style sits above a large ovary that is surrounded by post-like filaments and thick tepals.  Honey ants can be seen feeding on flower bud resin.

As flowers pass anthesis, pedicels twist upward so that developing green, tough, seed capsules are upright.  Capsules, about 2½ inches long and 1 inch wide on woody pedicels and stalks, are composed of three elongate carpels that are divided into two locules, each with a stack of seeds.  A capsule, with an exterior that is rounded along each elongate carpel, contains 100+ seeds.  When capsules dry in late fall, they become papery and split from the top between carpels.  As capsules open, hundreds of flattened, rounded papery black seeds are shaken out on windy days and become scattered.   Dead stalks and racemes are somewhat woody and may persist for several years.

For a partially shady to sunny garden or natural area, Arkansas yucca can provide a dominant accent.  It has year-round presence, but its occasional flowering would be the highlight of a year.  Its large flowers dramatize its flower parts and its mutulistic relationship with yucca moths can be easily viewed.  In addition to the yucca moth, yucca plants are host plants for caterpillars of giant-skipper butterflies, including Megathymus yuccae, which is rare in Arkansas.

Identification of yucca species and their varieties has found disagreement among various authorities.  In Arkansas, four additional species are recognized: Yucca filamentosa (common names: Adam’s-needle, Spanish-bayonet or yucca), a Southeastern U.S. native introduced to Arkansas;  Yucca flaccida (same common names: Adam’s-needle, Spanish-bayonet or yucca), also a Southeastern U.S. native introduced to Arkansas; Yucca louisianensis (common names: Louisianna yucca, Gulf Coast yucca or sandhill yucca), a native to south Arkansas; and Yucca freemanii (common name: Freeman’s yucca), a native species discovered new to Arkansas in Miller County in 2014.  Characteristics that can help distinguish Yucca arkansana from these other species:  1) leaf rosettes of a plant are separated by a short distance, instead of bunched-up, 2) there are relatively few leaves per rosette and these are thin and pliable with weak pointed tips, 3) curly marginal leaf hairs are not twisted, 4) flowering stalks are generally less than 4 feet, 5) inflorescence is a raceme, instead of a panicle, and 6) color of style is a contrasting green within a whitish green flower.

*   Yuccas and yucca moths, totally dependent on each other for natural reproduction, represent an example of mutualism.  The moth species that pollinates Arkansas yucca (as well as some other yuccas) is Tegeticula yuccasella.   Female moths pack pollinia into a ball that they carry in their coiled palps to another plant.  Moths use their egg-laying abdominal appendage (ovipositor) to insert an egg into a chamber (locule) of the ovary.  The transported pollinium ball is then forced into the recessed orifice of the stigma to effect pollination.  The moth caterpillar, as it grows, ties a dozen or so ovules together as they are eaten, leaving hundreds of viable seed.  Mature caterpillars drop to the ground to pupate in the soil until the next year’s flowers are available.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Marginal Wood Fern

Marginal wood fern (Dryopteris marginalis) of the Wood Fern (Dryopteridaceae) family, an evergreen, twice-cut fern, occurs throughout much of the eastern U.S. from Texas and Minnesota to the Atlantic Coast, but is mostly absent from the Gulf Coastal Plain and unknown from Louisiana and Florida.  In Arkansas, it has been documented to occur in the northwestern half of the state in the Interior Highlands.  The genus name is based on the Greek words for “oak” and “fern” which relates to occurrence of wood ferns among oak forests.  The specific epithet relates to the location of sori (spore clusters) near the margins of the leaf divisions.  Other common names include marginal shield fern, evergreen wood fern and leather-leaf wood fern.  This fern favors areas with damp to dry soils found in partially to fully shaded, rocky ravines, stream banks and north-facing slopes.

This medium-large fern has an elongate, reclined and compact rootstock, with dense, shallow and branching fibrous roots that grow directly from the rootstock.  New fronds grow from the center of the rootstock in late winter as tightly curled fiddleheads (or croziers).  Fiddleheads are densely covered with light-brown, soft scales and filaments, especially near their bases.  Scales and filaments, mostly absent along the leaf rachis (the midrib of the compound leaf), remain on the stipe (leaf stalk) of mature leaves.  The stipe and rachis, yellowish-green overall, with the stipe having a reddish base, have a central upper groove along the flattened upper side and a convex lower side.  The plant has a vase-like overall shape with an airy appearance.  Old fronds (an alternative term for fern leaves) wither around the rootstock, with the old stipes persisting for several years.

photo-1-january-11Photo 1:  Rootstock, as seen in this mid-January photo, bears green fronds which will decline when new fronds appear in late winter .  Previous year’s stipes remain.  Fibrous roots have been removed.

photo-2-april-6Photo 2:  In early April, fiddleheads grow from center of rootstock.  Previous year’s and older stipes can be seen.

Stipes are one-fourth to one-third as long as the fronds: fronds are up to 18 inches long and 6 inches wide, with stipes being about 8 inches long.  Plants, with fronds ascending and arching, may have a height and width each of about 2 feet.  Fronds are a bluish-green above and a lighter yellowish-green below.  Fronds have linear-lanceolate, quickly tapering pinnae (leaflets) that are mostly opposite lower on the rachis, changing to alternate higher toward the apex.  The leathery, glabrous pinnae, with tips arching toward frond apex, are longest mid-frond and slightly shorter toward the frond base (a semi-tapered fern).  Separation of pinnae, greatest at frond base, decreases toward frond tip as pinna length quickly shortens to form an acuminate frond tip.  Pinnae approaching frond tip are lobe-like.  Lower pinnae have very short petiolules (stalks) that are perpendicular to the rachis, with upper, short pinnae becoming sessile without overlap.  Pinnae are divided (a twice-divided fern) into oblong pinnules (sub-leaflets or secondary leaflets) which have rounded tips and margins that vary from slightly crenulate to well lobed near the base of the rachis.  Fronds may have 15 or so easily distinguishable pairs of pinnae before the pinnae become indistinct at the frond apex.  Similarly, pinnae may have 15 or so easily distinguishable pairs of pinnules before they become indistinct at the pinna tip. Main and secondary veins of pinnules, purplish on the underside, are of about equal size, nearly straight and forked.   Main veins of pinnules extend onto pinna midribs.

photo-3-january-11Photo 3:  In early January, fronds remain green.  All fronds of a plant grow from center of rootstock without any off-sets.

Fertile and sterile fronds are both photosynthetic and have the same appearance when viewed from above.  However, fertile fronds bear fruit-dots or sori* (singular, sorus) on the undersides of their upper (or distal) pinnae. Each sorus is a cluster of spore-producing sporangia.  From one to five sori are located along the margins of pinnules, except on those pinnules near the frond apex that are more lobe-like. Single sori are located at sinuses between the lobes.  Sori, which develop in late spring, are at first green, but then become dark brown.  They are covered by umbrella-like shields called indusia (singular, indusium).  Indusia are attached to the pinnule at the sori’s depressed center, loosely extending over many sporangia.  Each sporangium or spore case produces 50+ spores.  The depressed center of a sorus along with a depressed side cause the round sorus to appear reniform (kidney-shaped).  As the spore cases grow, they push the indusium aside.  When air moisture is low, spore cases pop open and dust-like spores are dispersed into the air.**

photo-4-marginal-fmid-right-1Photo 4:  Upper surfaces of an infertile frond (left) and a fertile frond (right) appear the same.  Lower side of a fertile frond, which has already dispersed its spores, is shown in the middle.  As shown, pinnae may be opposite or alternate.  Photo taken in mid-July.

photo-5-marginal-yPhoto 5:  Sori are located at margins of pinnules or singly at sinuses between lobe-like pinnules, as shown.  Note venation and slightly crenulate margins.  Photo taken in mid-July.

In a garden or natural areas, this evergreen, medium-large fern with its nice form and good texture can serve as an accent plant that provides interest throughout the year.  The plant does not colonize or spread by rootstock.  Dead fronds, spread around the rootstock, quickly disintegrate and tougher stipes, which disintegrate in two years, are not especially noticeable.  Marginal wood fern does well in partial to full shade.  It is not a preferred food choice of deer or rabbits.  Once established, it can survive dry periods.

photo-6-may-15Photo 6:  Marginal wood fern is an excellent accent plant for a shady garden.

In Arkansas, 12 taxa in the wood fern family (Dryopteridaceae) have been documented outside of cultivation, of which nine (including several of hybrid origin) are native.  Of the natives, only two species are widespread evergreen ferns, namely the subject species marginal wood fern (Dryopteris marginalis) and Christmas fern (Polystichum acrostichoides).  Christmas fern is a distinctive, once-cut fern with darker green and more leathery pinnae.

*   Sori – Greek for “heaps”.
**  With dispersal of spores, the above-ground “diploid sporophyte phase” of a fern’s life cycle (referred to as “alternation of generations”) concludes.  In the soil, spores germinate to produce a prothallus as the “haploid gametophyte phase”.  The prothallus produces mobile sperm gametes and attached egg gametes.  With fertilization of the egg, a diploid zygote may develop into a new diploid sporophyte plant.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Patridgeberry

Partridgeberry (Mitchella repens) of the Madder (Rubiaceae) family is an evergreen perennial with a trailing growth habit. It occurs in the U.S. from Texas to Oklahoma to Missouri to Minnesota thence to the Atlantic and Gulf Coasts. It occurs throughout most of Arkansas except for portions of the Mississippi Alluvial Plain and calcareous areas of the Ozarks. Mitchella repens is one of only two species of the genus that have been identified worldwide*. The genus name honors John Mitchell, an 18th century Virginia native, who worked with Carl Linnaeus regarding the flora of the New World. The specific epithet is Latin for “creeping”. Other common names include twinberry and twin-flower. Its preferred habitat is moist, well-drained, acidic and sandy, rocky or loamy soils in partially shaded woodlands where leaf litter is thin, including mossy areas.

Partridgeberry’s ground-hugging stems intertwine to form mats. Stems have short pubescence when young. Stems occasionally produce single lateral stems as well as pairs of stems at stem tips. New stem segments, mostly green to reddish or with purple coloration, grow straight in open areas. New seasonal growth, which may be up to 10 inches long, grows from apical buds in telescoping fashion, with stem diameter and leaf size decreasing toward the apex. Older stem segments lose their leaves and become brown as they become covered by subsequent plant growth and leaf litter. New segments bear root nubs on their lower side near leaf nodes and randomly between nodes, from which roots may grow upon contact with soil. Fibrous, descending branching roots can be 5 or more inches long. Leafless stem segments, becoming a permanent part of a plant, toughen and become slightly gnarly with age, but do not increase in size.

Patridgeberry - Mitchella repensPhoto 1: Roots may grow from near leaf nodes or elsewhere from the underside of stems.

Opposite, orbicular to cordate leaves, borne mostly along current year’s stem segments, have ¼-inch-long petioles. Lower ends of petioles are set at an acute angle toward the stem apex while the upper portion trends upward to allow leaf surface to face sunlight. Largest leaves, at the base of current season’s growth, are ¾ to 1 inch in length and width. Upper and lower leaf surfaces are glabrous, with the upper surface being a shiny dark green as compared to the dull light green lower surface. Leaves appear leathery with a lighter colored main vein on the upper surface and secondary veins that bend toward the leaf apex (arcuate). The leaf blade is mostly flat, but turns down to join the petiole. While plant height on open ground is less than ½ inch, within mats or growing among plant litter, plant height may be elevated several inches.

Patridgeberry - Mitchella repensPhoto 2: Current-year stem growth shown across upper-center of photo. Angle of petioles changes to orient leaves to sunlight. Note pale midribs of leaves.

Patridgeberry - Mitchella repensPhoto 3: With several years of growth, older stems become covered by newer stem growth and leaf litter. Largest leaves are at base of current season’s growth.

The inflorescence develops in early to mid-spring at stem apices and from leaf axils. Two funnel-shaped, half-inch-long upright flowers share a stubby light green calyx that is on a short pedicel. Each calyx-half has four central points that are reduced calyx lobes. In bud, corollas are glabrous on their exterior, narrow at their white bases, and inflated at their light lavender upper ends. With anthesis, four broad lobes with obtuse tips spread wide, exposing a white interior with dense, long white hairs. Four stamens are sited between the lobes, adnate (fused) to the corolla tube just below lobes. Elongate anthers are aligned with the floral tube. A single style is topped with four long, down-turned stigmas. Stamens and pistil are typically white, although filaments may be tinged with purple. The nectary is positioned above the inferior ovary.

Partridgeberry has dimorphic flowers–they appear in two forms or morphs. One morph has a long style with its stigmas well exserted  beyond the corolla and stamens that remain within the corolla tube (referred to as the “pin” morph). The second morph has a short style so that stigmas remain well within the corolla tube, while stamens are exserted well beyond the corolla (referred to as the “thrum” morph). An individual plant bears flowers that are either pin or thrum, but not both. This intriguing adaptation that increases the chance of outcrossing, rather than self-pollination, is called heterostyly.

Patridgeberry - Mitchella repensPhoto 4: In this early May photo, flower buds are shown at the top of photo and several flower pairs and calyx pairs are shown lower in photo.

Patridgeberry - Mitchella repensPhoto 5: In this mid-May photo, flower buds are seen along with an open corolla that shows the pin morph of dimorphisim. Note arcuate leaf venation and calyx bearing two corollas.

After corollas fall off, the upper portion of the inferior ovary has two adjoining, flattened scars that are remnants of the perianth (calyx + corollas). With successful pollination, the two fused ovaries beneath the scars enlarge to form a single fruit (a berry-like drupe). The mature and very distinctive fruit becomes bright red and bears toward the tip its two now-prominent perianth scars, like two craters, no longer adjoining but now well separated due to the fruit’s enlargement. Fruits, about 1/3 inch across, are often persistent into spring. The thin red exocarp (skin) surrounds a white, mealy interior with about four embedded stones. The fruit is edible, but rather tasteless.

Patridgeberry - Mitchella repensPhoto 6: In this early December photo, this partridgeberry was growing among moss and lichens near pine trees. Perianth scars remain evident along with calyx remnants, especially in the upper fruit. Inset shows fruit’s interior and stones.

For a shade garden with acidic soil, partridgeberry is an excellent plant which is especially noticeable and decorative in winter. Low-growing stems bear year-round, fresh-looking leaves accented with small white flowers in mid-spring and strikingly red fruit from fall into spring. This shallow-rooted plant can be ideal as a ground cover or as understory to shrubs.

*The second species in the genus is Mitchella undulata which occurs in eastern Asia.  Appearance of this Asian species is similar to Mitchella repens.

Article and photographs by ANPS member Sid Vogelpohl

 

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Know Your Natives – Dittany

Dittany (Cunila origanoides) of the Mint (Lamiaceae) family is a small, herbaceous perennial that produces “frost flowers”.  Dittany, the only species of the Cunila genus in the U.S. (the rest are in Central and South America), occurs from northeast Texas to extreme southeast Kansas to New York, thence south to Louisiana, northern Mississippi, northern Alabama, northern Georgia and South Carolina.  It is absent from Florida and much of the Gulf Coastal Plain.  In Arkansas, it occurs throughout much of state, but is absent from lowland portions of the Mississippi Alluvial Plain and West Gulf Coastal Plain.  Its preferred habitat is dry, well-drained soils found in sunny to partially sunny, rocky or sandy open woodlands on slopes and ridges where competition from other species is limited.  The genus name is based on an ancient Latin name for a fragrant plant, possibly a mint, that was transferred to this group of New World mints.  The specific epithet means “resembling oregano”, of the Old World genus Origanum, some species of which it both looks and smells like.  The common name “dittany” may also originate with a member of that genus, specifically dittany of Crete (Origanum dictamnus) or from its namesake, Dictamnus albus in the rue or citrus (Rutaceae) family.  Other common names for Cunila origanoides include common or American dittany, stone mint, false or wild oregano and frost mint.

Dittany has numerous widely spreading, shallow roots from a caudex.  In late fall, short rhizomes grow from the caudex that produce the following year’s herbaceous growth.  Spring-time stems, lower sides of leaves and leaf margins are pubescent, but these become glabrous by mid-summer.  Plants may consist of several stems that form an open, lanky plant or many stems that form a dense rounded plant.  Dittany has four-sided, rounded, wiry and erect stems that are purple in the spring, fade to reddish when at bloom and become brown and seemingly woody in fall.  Stems bear opposite leaves, with successive leaf pairs rotated from one to the next to varying degrees.  Leaf pairs tend to produce “matched sets” of branches or inflorescences.  Stems typically grow to about 8 inches tall, but may reach 1½ feet.  Branches may be 6 inches or more long, with length decreasing from lowermost to uppermost branches.  Shorter sub-branches may be present.  Frozen stems, which are persistent, retain dried inflorescences and scattered leaves into the winter.

During spring growth, dittany has heart-shaped (cordate) leaves that are dark green above with purple shading while the lower surface is mostly purple, but with green increasing with time.  With maturity, leaf shape becomes acuminate (tapering to a long tip) with a base varying from rounded to wedge-shaped.  Mature leaves have medium green upper and lower surfaces.    Leaves lowermost on stems are up to 1½ inches long and ¾ inch wide with leaf size decreasing at a uniform rate toward ends of branches.  Higher on stems, leaf size may be ¼ inch long and 1/16 inch wide and even smaller in the inflorescence.  Leaves have margins with shallow teeth that point toward the tip (serrate) and very short petioles.  Irregularly spaced secondary veins gradually curve off the mid-vein to align with leaf margin.  Leaves are punctate (with tiny spots on surface).  Fresh crushed leaves have a strong but pleasant minty aroma.

Dittany - Cunila origanoidesPhoto 1:  This dittany plant, shown in late March, bears heart-shaped leaves and has pubescent stems, lower leaf surfaces and leaf margins.

Dittany’s inflorescence in late summer consists of clusters of small cymes that grow directly from paired leaf axils along upper portions and ends of branches.  The inflorescence from an individual leaf axil consists of a single short “branch” that divides into several stalks bearing three to five flowers on very short pedicels.  At ends of branches, cymes are crowded together.

Tubular lavender flowers appear from late summer into early fall and are up to 1/3 inch long.  Floral tubes have four flared, rounded lobes comprising two identical lateral lobes and two longer lobes with an upper lobe that is slightly notched.  Lobes may have light to dark purple splotches.  The exterior of the floral tube is covered with tiny lavender hairs.  Two slender lavender stamens and a pistil with a split (bifurcate) stigma are exserted from the tube about half the length of the tube.  Purplish anthers, set knob-like at ends of filaments, become brown.  Floral tubes are set in tubular greenish or purplish calyxes that are less than half as long as the exposed portion of the floral tubes.  Calyxes, also punctate, have five short, equally-sized triangular lobes with ten prominent veins.  The interior of a calyx is lined with shaggy, white (villous) hairs that are pushed aside as the floral tube emerges.  The white hairs, retained after the floral tubes have fallen off, noticeably project out of the calyxes.

Dittany - Cunila origanoidesPhoto 2:  A lanky plant in bloom in a sunny rocky site.  Photo taken in late September.

Dittany - Cunila origanoidesPhoto 3:  Flowers have four rounded lobes, strongly exserted stamens and pistils and exterior pubescence.

Dittany - Cunila origanoidesPhoto 4:  In late November, floral tubes having fallen off and calyxes are accented by white hairs.

A fertilized flower produces a dry schizocarp fruit that splits into two to four tiny, chocolate-brown, slightly flattened and hard 1-seeded nutlets with rounded sides.  Nutlets have a short nipple at one end.

Dittany - Cunila origanoidesPhoto 5:  Display shows a cluster of cymes along with a separated 1/8-inch-long calyx and nutlets.  Note villous hairs extending out of calyxes.

Dittany is one of few native forbs that produces frost flowers.  Two other species that produce frost flowers consistently are frostweed (Verbesina virginica) and camphorweed (Pluchea camphorata).  Dittany tends to first produce frost flowers at colder temperatures than frostweed or camphorweed.  For information regarding frost flowers see “Know Your Natives” articles posted November 26, 2013  and December 16, 2014.

Dittany - Cunila origanoidesPhoto 6:   A dittany plant with frost flowers in late December.  Frost flowers may be “regrown” from an individual stem on successive cold nights.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Possumhaw

Possumhaw (Ilex decidua) is a deciduous shrub or small tree in the holly (Aquifoliaceae) family that bears showy winter fruit.  In the U.S., it is found throughout the Southeast from central Texas to southeastern Kansas, to southern Illinois, east to Maryland, and thence to the coasts.  The species occurs statewide in Arkansas.  The genus name comes from the classical Latin name and later the specific epithet of holm or holly oak (Quercus ilex) which has evergreen holly-like leaves.  Other common names for possumhaw* include winterberry*, deciduous holly and swamp holly.  Possumhaw, frequently seen in fencerows and in the home landscape, may be found in nature in various moist to dry soils of upland glades, lowlands, and margins of wet areas.  Plants are drought and flood tolerant.

Possumhaw is a multi-stemmed plant reaching 15 or more feet tall.  It continues to add new stems from its root to form tight clumps of stems so that the plant’s base may eventually be 2 to 3 feet across.  Sucker plants may appear a short distance from the original plant.  Possumhaw exhibits “weak apical dominance”; that is, its greatest growth does not arise from tips of branches.  Stems, at first somewhat vertical become arched with age and new stems (adventitious stems) arise from the top of the arch.  These adventitious stems may grow two to six feet in a single growing season and, in future growing seasons, become arched as the growth cycle continues.  Internally and at the perimeter of the plant, the many horizontal to descending branches are relatively fast growing with apical growth of these branches continuing from year to year.  Branches bear slower growing twigs to about eight inches long and very slow growing “spur shoots” up to two inches long.

In earlier years of growth, possumhaw tends to be fast-growing and mostly erect and slender while, with maturity, it develops a broad rounded shape that is widest at its middle, with branches not usually arching completely to the ground, so that its multi-stemmed base is often clearly visible.  Mature stems and branches have thin, smooth, gray bark with splotches of white, along with prominent lenticels (pores).  Twigs have thin gray bark, but spur shoots are roughened by closely spaced leaf and flower scars from previous years’ growth.  With heavy shading, internal branches, twigs, spurs, and even stems die out.

Possumhaw - Ilex deciduaPhoto 1:  From year to year, stems multiply and become crowded.  Note lenticels (prominent white corky dots).  Green stems on right are a greenbrier (Smilax sp.).  

Small, pointed leaf buds produce twigs with simple leaves that are up to 3 inches long and ¾ inch wide with a blunt tip.  Leaves are cuneate (narrowly wedge-shaped) at base and wider in the upper half.  Where sufficiently spaced, leaves are alternate, but those at ends of spur branches are so close together that they appear to be fascicled.  Leaves, glossy green above and a paler green below, have finely crenate margins.  The upper half of a leaf is down-turned.  Veins are pinnate with lateral veins from the mid-vein being off-set.  Leaves are glabrous except for short dense hairs on the principal abaxial veins.  Leaves, falling gradually from fall into winter, do not produce appreciable fall color but are often yellowish.

The inflorescence, developing in early spring, consists of small, solitary flowers or (usually) clusters of two to five or more.  Flowers develop along branches, at the base of branches, along twigs and at tips of spurs.  Typically, each flower grows from a leaf axil, but flowers may also appear without a subtending leaf.  A plant with sufficient sunlight has flowers uniformly spread throughout the plant.

Possumhaw - Ilex deciduaPhoto 2:  This mid-April photo shows twigs bearing female (left; note also fruit still remaining from previous season) and male (right) flowers.  These male flowers have five petals, which is not typical (usually there are four).  Spur shoots lengthen a minute amount each year as flowers and leaves grow from the tips.  Note midrib pubescence of leaves on left.

Flowers, ¼-inch in diameter, are on slender pedicels (no peduncles).  Flowers, with tiny cup-like, green calyxes, generally have four (sometimes five) white, rounded petals.  Possumhaw is considered to be dioecious (male and female flowers on different plants), but female flowers may have stamens with infertile anthers.  Round, superior ovaries of the pistillate flowers have round, stubby, flattened stigmas without a noticeable style.  Pedicels, calyxes and ovaries are a smooth light green while the stigma is a yellowish green.  Stamens, anthers and pollen are whitish.

Possumhaw - Ilex deciduaPhoto 3:  This third-year twig is developing greyish bark and spur shoots.  Flowers have pedicels which grow directly from spur tips.  Pistillate flowers may have infertile stamens, as shown (see arrows).  Fruit sometimes remains on plant into following growing season.

Fertilized flowers produce round, green berries that become 1/3-inch-diameter orange-red to bright red in mid-fall.  Mature berries, persisting from fall into spring (unless eaten by wildlife), are firm with a fairly thick skin that encloses yellow, juicy bitter pulp and four or five light tan, 1-seeded stones that are less than ¼-inch long.  Seeds have the shape of an orange segment with several ridges along its three sides.  Stones are widely dispersed by birds and small mammals.

Possumhaw - Ilex deciduaPhoto 4:  With sufficient sunlight on individual branches, fast growing current-year twigs may bear fruit on their lower portion.  Photo taken in the mid-July.

photo-5-october-21-revisedPhoto 5:  In this mid-October photo, fruit are becoming red.  Note texture of very slow growing spurs roughened by leaf and pedicel scars.  Inset shows ridged, 1-seeded stones..

In a garden or natural area, possumhaw exhibits interesting structure along with reliable production of brightly colored berries (female plants only).  It is especially striking as a stand-alone specimen in partial to full sun.  Sunnier sites produce fuller plants and heavier fruit crop.  Other than possibly removing some basal stems as they sprout, additional trimming would negatively affect its natural structure.  The berry-like drupes and leaves are not messy.

Possumhaw - Ilex deciduaPhoto 6:  Possumhaw’s fruit is further enhanced by snow and ice.  Fruit-bearing shrub at base is corral berry (Symphoricarpos orbiculatus)

In Arkansas, six additional native or naturalized Ilex species have been documented:  Carolina holly (Ilex ambigua), scattered throughout much of the state but not especially common; the non-native Chinese holly (Ilex cornuta); Georgia holly (Ilex longipes), known from the state only in the Ouachita Mountains and considered a species of conservation concern by the Arkansas Natural Heritage Commission; American holly (Ilex opaca), known throughout much of southern, central, and eastern Arkansas; winterberry (Ilex verticillata), known from only a handful of sites in the state and also considered a species of conservation concern; and yaupon (Ilex vomitoria), native in the state originally to the Ouachita Mountains and perhaps the adjacent Coastal Plain, otherwise occasionally escapes from cultivation elsewhere.  Of these, Ilex ambigua, Ilex longipes and Ilex verticillata are deciduous, as is possumhaw.  Ilex ambigua can be distinguished by its dark brown to black, smooth bark (with flaking on old stems), toothed leaves, and elliptical, 1-seeded fruits (drupes).  Ilex longipes looks most similar to possumhaw, and has even been treated as a variety of Ilex decidua in the past.  It has flowers on longer pedicels, leaves lacking the dense hairs on the undersurface veins, and more consistently grows in drier, upland sites.  Ilex verticillata is smaller than possumhaw, typically grows in wet areas, has larger serrated and elliptic leaves that are rugose on the top, and its four or five stones are smaller and not ridged.

  • The common names “possumhaw” and “winterberry” are also used for other species; namely Viburnum nudum is also called possumhaw and Ilex verticillata is also called winterberry.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Evening Rain-Lily

Evening rain-lily (Cooperia drummondii, also known variously by some athorities as Cooperia chlorosolen or Zephyranthes chlorosolen) of the Amaryllis (Amaryllidaceae) family, formerly of the Lily (Liliaceae) family, occurs in the south-central United States from New Mexico to Kansas to Alabama and then thence south to the Gulf Coast and into Mexico.  In Arkansas, it is recorded from five counties scattered in the western portion of the state and is considered of “conservation concern” by the Arkansas Natural Heritage Commission.  It is currently the only species of the Cooperia genus known from the state.  The specific epithet recognizes Thomas Drummond, an 18th century Scottish naturalist that first discovered this species.  Other common names are “cebolleta” (a Spanish word alluding to the plant’s vegetative resemblence to onions [cebollas]) and Drummond’s rain-lily.  This species is found in prairies, glades, savannahs and woodland margins in a wide variety of dry to moist soils and in varying sunlight situations.  Evening rain-lilies are perennial, herbaceous, bulbous plants that germinate with a single seed leaf or cotyledon (placing them in the class of flowering plants familiarly called monocots).  The species has “true bulbs” which have a basal plate (caudex) that produces new roots annually, leaves, flower stems and lateral bublets.*  Its life cycle during the temperate months is responsive to rainfall patterns; especially in late summer, hence the common name “rain-lily.”

Leaves continually grow within the bulb at the center of the basal plate with the most immature leaves at the center of a “leaf core.”  Leaves appear at the surface, somewhat erratically, in response to air temperature and soil moisture.  Leaves are most numerous in spring (without any associated flower stems), absent during hot dry summer months and may appear intermittently during the summer and fall (after flower stems appear in response to rain).  Leaves have long, smooth, narrow, grey-green blades that may be 12 or more inches long and ¼ inch wide, with rounded tips.  Leaves are in-folded along their entire length (more so near their bases) as a result of having been tightly pressed against other leaves during development within the bulb.  Leaves tend to be somewhat twisted and lax, almost floppy.

Each leaf consists of an above-ground blade and an underground conical white base for water and nutrient storage that is concentric around the leaf core of the bulb.  Bases are tightly overlapped and are pushed away from the center of the bulb as new leaves develop.  With leaf bases being thicker at their mid-section, bulbs become rounded in lateral as well as vertical cross-section.  Outermost leaf bases become thinner to a brown, tissue-like tunic before eventually disintegrating.

Evening Rain Lily - Cooperia drummondiiPhoto 1:  The twisted and somewhat floppy leaves of evening rain-lily seen in this early April photo grow in clusters from tips of bulbs and bulblets.  Each leaf has a thick white base that encircles the bulb’s core of immature leaves.

Flowering occurs sporadically in summer into fall months several days after significant rainfall.  A bulb produces one flower stem at a time.  Flower stems originate from the basal plate between two leaf bases close to the leaf core.  The stems follow the curvature of these two confining leaf bases to emerge at the top of bulbs, slightly off-center (leaves being at the center).  Flower stems are pinkish at first, but become mostly green with the approach of anthesis.  Upon emergence, the upper portion of the stem is covered by a bluntly pointed spathe that is the same color as the overall stem.  The lower end of the spathe joins the stem immediately below the ovary, which is located up to 7 inches below the perianth (corolla + calyx) that emerges from within the spathe.  Stems are slender, round to flattened, and hollow.  Stems, which may be 12 or more inches long and weakly erect, are smooth and mostly equidimensional their entire length.  The spathe peels back to below the ovary and quickly dries.

When a larger bulb is cut laterally at mid-bulb, along with prominently displayed concentric leaf bases, small flattened ellipses squeezed between leaf bases can be seen.  These ellipses, lined up along an axis across the bulb, are either stems that have already produced seed (these are flattened brown ellipses) or would have produced stems at a later flowering episode (these are light colored ellipses).  With a bulb producing one flower at a time, the sequence alternates from one side of the leaf core to the other.

Evening Rain Lily - Cooperia drummondiiPhoto 2:  Bulb-section at center of photo is lower half of a bulb while upper half of same bulb is arranged radially from ‘A’ through ‘O.’  ‘A’ is the leaf core composed of a half-dozen variably immature leaves at the bulb’s center (corresponding to the portion indicated with the arrow on the cross-section).  Numbers ‘1’ through ‘5’ indicate stem sites with ‘2’ corresponding to ‘D’ (a wilting flower stem).  ‘O’ represents the outer tunic.

Evening Rain Lily - Cooperia drummondiiPhoto 3:  In this mid-August photo, stems emerge after significant rainfall.  Spathes recede as flowers continue to grow.  Arrows point to ovaries.

Flowers gradually open in the evening several days after rainfall and remain open a day or two.  Flowers, about 2 inches wide, have three mostly white sepals and three almost identical petals (together referred to as tepals) with a somewhat elongated ruffled oval shape.  Tepals are of equal size and shape with a white upper surface along with lighter longitudinal veins.  Sepals have pinkish beaks (remnants from when in bud) at their apices with that pinkish color extending partially down their lower sides.  Flowers have six stamens with elongate, equal-sized anthers on short, down-bent filaments that position anthers close together and vertically so that the lower ends of the anthers are within the flower’s throat.  Filaments are attached (adnate) to the tepals’ base just above the lower ends of the anthers.  Pistils, up to 7 inches long, are free-standing from the inferior ovary, up the exceeding long tubular perianth (envelope surrounding sexual organs) with the stigma hidden immediately below the lower ends of anthers.

Evening Rain Lily - Cooperia drummondiiPhoto 4:  At full bloom, stems remain pinkish near their bases and above the ovaries (arrow).  Note new leaves emerging at base of stems.

Evening Rain Lily - Cooperia drummondiiPhoto 5:  Elongate, upright anthers surround and hide the stigma.  Three petals are positioned between three sepals.  Note beaked sepals of flower and buds.

Flowering stems emerge, flower, and then produce seed over about an 8-day period.  With fertilization, the perianth quickly wilts and dries, but may remain on the ovary until seed capsules mature.  Ovaries enlarge to form a prominently three-chambered (trilocular) stubby capsule.  With bulging chambers, capsule width equals the length.  As the capsule dries, the top shrinks back to expose thin, shiny black, papery seeds in loosely layered stacks.  Seeds readily fall from the opened chambers with slight movement of the capsule.  The plant is a reliable vigorous seed producer due, perhaps, to the close contact of anthers and stigma along with the services of pollen-eating insects.

Evening Rain Lily - Cooperia drummondiiPhoto 6:  Seed capsules are composed of three bulging chambers.  Flat papery seeds are loosely stacked within each chamber.  Note dried perianth remaining attached to green capsule on left.

For a sunny moist to dry garden or natural area, evening rain-lily can surprise a person with the sudden appearance of flowers.  The flowers are eye-catching as are the seed capsules.  Along with multiplying via offset bulblets, many additional seedling plants should be expected.  Seedlings can be controlled by removing capsules prior to maturing.


*  Plants that store water and nutrients in fleshy underground structures to survive cold or dry conditions in a dormant state are called “geophytes.”  In addition to bulbs, other geophytic structures are corms, tubers, tuberous roots and rhizomes.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Sweet Everlasting

Sweet everlasting, Pseudognaphalium obtusifolium (formerly Gnaphalium obtusifolium), of the Aster (Asteraceae) family is an herbaceous annual.  In the U.S., it occurs from Texas to Nebraska to Minnesota and thence east and south to the coasts, including most of Arkansas.  Natural habitats are mesic to dry sandy areas in prairies, glades, open woods and open disturbed sites.  The common name “sweet everlasting” relates to a light pleasant scent and the durability of fresh dried cuttings.  Another common name is “rabbit tobacco” (this name is also applied to other species in the genus) based on the plant having been used as tobacco by Native Americans and early American settlers.

Sweet everlasting has a rambling, rough, woody tap root along with smaller, variably-sized, near-horizontal roots from the tap root and caudex.  Seeds germinate in late fall and plants overwinter as low basal rosettes of broadly linear leaves, maturing the following year.  Leaves are widest above mid-blade with an extended taper to a blunt (spatulate) apex.  From mid-leaf to leaf base, margins have a gentler taper.  Basal leaves are tomentose (with dense matted woolly hairs) on both adaxial (upper) and abaxial (lower) surfaces.  Leaves are a muted whitish light green color, due to their tomentose nature, and are smooth as velvet.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 1:  Basal rosettes of sweet everlasting grow overwinter.  In this early March photo, tomentose leaves are evident.

A mature plant in mid- to late-summer may have one to a half-dozen erect stems that may reach 2½ feet tall.  The terete (round), somewhat hardened stems are not branched except along their upper portion where many secondary, ascending branches occur.  These branches, in turn, have tertiary branches toward their tips.  Stems and branches, too, are tomentose, thus stems are light green to white.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 2:  In late May, stems remain unbranched and adaxial leaf surfaces are glabrous.

Stem leaves are entire, linear, sessile and clasping.  Largest leaves may be 3 inches long and 1/3 inch wide with a slightly pointed tip.   Leaf size gradually decreases up main stems and along branches.  Stem leaves are jade green on the adaxial side which is glabrous, or nearly so, while the abaxial side is uniformly tomentose so that they have a whitish cast.  Leaf arrangement is varied from closely spaced and whorled around the stem as well as alternate or opposite.  Leaves fold inward along the midrib and margins are somewhat undulated.  Venation, although pinnate, is indistinct except for the midvein which is slightly recessed adaxially and expressed abaxially.  With anthesis (flowers open and functioning), and especially with drying soils, stem leaves dry from the ground up, but remain on the stem and become twisted.  With killing frost, dry leaves throughout the plant become brown above and silvery below and remain into winter months.

Inflorescences develop from late summer into early fall.  Inflorescences occur at the ends of branches with a number of branched peduncles, each terminating with up to five closely spaced flower heads on separate pedicels.  Although flower heads of common peduncles are arranged in a corymb (lower heads have longer pedicels), with branches growing from different levels of main stems, the overall inflorescence at the apex of a stem is domed.

Flower head buds have elongated cone shapes with a pointed apex and rounded base.  The exterior of buds is formed by thin, oblong-lanceolate phyllaries (bracts) that are covered with dense, matted hairs (the longest hairs on the plant).  The dense hairs mask details of the phyllaries which are appressed and overlapped in five or so series.

The composite flower heads are composed of only disk flowers which stay well hidden within the tight involucres (phyllaries, collectively).  At anthesis, only the tips of corollas and stamens are seen as a flat yellow surface, with individual florets being indistinct.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 3:  In late August, yellow-topped flower heads are at anthesis (this inflorescence covered in morning dew).

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 4:  In late September, some flower heads remain in bud while others have developed seed.

Florets mature to produce achenes (1-seeded nutlets) with long whitish to straw-colored pappus (tufts of hairs at the top of the achenes).  At seed maturity, the involucres spread wide and the achenes tend to disengage from the receptacle in clusters.  The tiny, elongate, narrow achenes are then dispersed by wind via the pappus.  With the seeds gone and the loss of tomentose hairs, the structure of the involucre is more obvious and four or five series of phyllaries are easily seen.  Phyllaries, almost translucent at this time, have a light green lower central stripe.  Phyllaries in the lower series are shorter and broader than the lanceolate ones in the upper series.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 5:  In early October, with dry summer months, many lower stem leaves have dried.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 6:  Display of maturing corymbs in mid-October, when achenes are dispersing.  Note achene with pappus in left corymb (arrow) and empty flared involucres and exposed receptacles in right corymb.

At least two other species of the same genus as sweet everlasting are found in Arkansas; namely, red-tip rabbit tobacco (Pseudognaphalium luteoalbum) which is found in over a half dozen scattered counties in south Arkansas and rabbit tobacco (Pseudognaphalium helleri) which is found throughout the southern half of the state.  The non-native red-tip rabbit tobacco (P. luteoalbum) has 1) tap or fibrous roots, 2) similarly tomentose stems and leaves, 3) stem leaves that are more narrow and elongate with decurrent margins (extending down stem below point of leaf attachment), 4) flower heads on very short peduncles/pedicels that are closely grouped at the apex of main branches, and 5) red-tipped corollas.  The native rabbit tobacco (P. helleri) has an overall structure very similar to sweet everlasting, but P. helleri has 1) fibrous roots, 2) stems and leaves that are green with glandular-stipitate hairs at maturity instead of tomentose, and 3) medium green lanceolate leaves.

Other plants that have a very similar appearance during late winter and can occur in the same habitats as sweet everlasting are the related cudweeds (genus Gamochaeta, also formerly of the genus Gnaphalium), of which there are at least seven species (some native and some non-native) in Arkansas (including Gamochaeta purpurea, G. argyrinea, etc.).  Cudweeds have fibrous roots, leaves that are generally shorter and more broadly spathulate, and leaf pubescence that feels smooth rather than velvety.  Upon growth of stems and inflorescences, they are more easy to distinguish from sweet everlasting.  Flower heads of cudweed are sessile to very short-stalked and occur in tight clusters or spikes of clusters.

Sweet everlasting - Pseudognaphalium obtusifoliumPhoto 7:  Plants at left and upper positions are sweet everlasting (Pseudognaphalium obtusifolium). Lower right plant is a cudweed (Gamochaeta sp.).

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – White Oldfield Aster

White oldfield aster (Symphyotrichum pilosum), formerly Aster pilosus, a herbaceous perennial of the Aster (Asteraceae) family, occurs from Texas to South Dakota and Minnesota thence to the Atlantic and Gulf Coasts.  In Arkansas, this aster occurs statewide and is one of 22 species of aster (Symphyotrichum) konwn to occur in the state.   Habitats for this aster include old fields, open woodlands and roadways with a wide variety of dry to mesic soils.  The genus name is from Greek for “junction” and “hair”, apparently based on a European cultivar.  The specific epithet is from Latin for “hairy”.  Other common names include white heath aster, hairy aster, frost (based on dense hairs) aster, and awl (based on shape of phyllaries) aster.

In late fall, after flowering, basal leaf rosettes appear and that persist over winter.  Basal leaves are oval to elliptic with a narrowed base that may be glabrous or have scattered hairs on upper leaf surface as well as short marginal (ciliate) hairs.  These leaves, which may be 3 inches long and an inch wide, have entire margins or a few widely spaced shallow serrations.  The adaxial (upper) leaf surface is medium green, while the abaxial (lower) surface is a slightly lighter green.  Each basal rosette produces a stem.

White oldfield aster - Symphyotrichum pilosumPhoto 1:  In November, stems are frozen and overwintering basal rosettes appear.  Old stems retain pubescence.  Ciliate (marginal) hairs can be seen on new leaves.

White oldfield aster grows in clumps (cespitose) from a caudex and has both fibrous roots and rhizomes.  Young stems are a medium green, but as the terete stems mature the color changes to brown or reddish brown and stems become hardened.  Mature plants have tall lanky stems that may reach 5 feet.  The largest stems may have splits in their epidermal layer due to lateral growth pressure.  Pubescence of short hairs typically covers the entire stem.  The stout, straight stems tend to lean in various directions from the caudex.  Dead stems persist well into the next year, still exhibiting pubescence.

Stem leaves are alternate, simple and spaced 1½ to 4 inches apart.  Clusters of leaves (fascicles) arises from the leaf axils.  Leaves in these fascicles become alternate leaves along growing branches.  Lower, down-stem, branches may be an inch or two long, while higher, up-stem, branches may reach 12 or even 16 inches.  The longer branches also produce fascicles that become secondary branches.

White oldfield aster - Symphyotrichum pilosumPhoto 2:  In mid-May, new stems may be 3 feet tall.  Note pubescent stems, ciliate leaf margins, winged bases of stem leaves, and fascicles of leaves from leaf axils that will grow into branches.

Leaves along stems (cauline leaves) and branches differ in size and shape from the basal leaves.  The largest leaves, cauline leaves and those lower on branches, may be 4 inches long and ½ inch wide at mid-leaf and have a very gentle taper to leaf tips (acuminate).  Leaf width from mid-leaf to leaf base reduces down to narrow wings that continue to the sessile and clasping leaf base.  Leaves have entire margins or small widely spaced serrations.  Slight up-folding occurs along midrib which is especially prominent along the winged base.  Along with short ciliate hairs at leaf margins, similar scattered hairs occur on adaxial leaf surface while abaxial surface is more hairy with concentrations along primary veins and the leaf base.  Leaves are thin and feel slightly rough.  The color on both sides of leaves is a similar medium green.  As plants mature in fall, especially with drying soils, lower leaves wither and drop off.

White oldfield aster - Symphyotrichum pilosumPhoto 3:  In mid-October, pubescent stems are hard and brown.  Lower along stem, axillary branches that bear flowers are shorter, as shown.

Leaves on branches that bear the inflorescence become smaller upwards, first becoming broadly acicular (needle-shaped), to acicular, then to bract-like.  These leaves and bracts, also sessile, have the same color and pubescence as the larger leaves, though without winged bases.  The acicular leaves, which may be ½ inch long and 1/16 inch wide, further decrease in size to tiny acicular bracts.  Bracts are especially numerous at the ends of the longest branches and secondary branches.

The inflorescence, a series of composite flower heads along branches, occurs along and toward the ends of widely spreading and ascending, short to long branches.  The longest flowering branches tend to occur about mid-upper-stem with shorter braches below and above.  Branches have alternate leaves or bracts that are separated from each other by about ½ to 1/8 inch or less.  Leaf/bract size and separation decreases toward the ends of branches.  Leaves or bracts within the inflorescence subtend a single flower head or a fascicle that may produce a secondary flowering branch.  Flower heads at the ends of branches or secondary branches bloom first, with development continuing down-branch over a month or two if conditions remain favorable.  When stems lean to a great degree, flower heads bend to the sunny side, becoming secund (oriented to one side).  Bracts just below flower heads have acute tips that grade into the similarly sized and shaped phyllaries.

White oldfield aster - Symphyotrichum pilosumPhoto 4:  In mid-October, plants may be 5 feet tall with many branches and secondary branches.  Fragrant or aromatic aster (S. oblongifolium) is shown at lower right.

Flower heads, to about ¾ inch wide, have 20+ pistillate ray flowers and 25+ perfect yellow disk flowers.  Ray flowers have widely spreading strap-like ligules, normally white, about ¼ inch long and 1/16 inch wide.  Tubular disk flowers, with yellow 5-lobed corollas and yellow stamens, become reddish with age.  Flower heads are set in an elongated urn-shaped involucre composed of closely spaced, sharply pointed, 1/8 inch, awl-shaped, overlapping, stiff bracts (phyllaries) in 4 to 6 irregular layers (series).  Phyllaries are appressed on their lower portion and upward-flared on upper portion.  Involucres are the same medium green as leaves, but with lighter green bases due to bract growth.  Pedicels, subtended by acicular bracts, are not more than ¼ inch long.  The elongate inferior ovaries of the ray and disk flowers have bristly structures (pappus) at their upper ends.   The white styles of ray flowers and yellow styles of disk flowers have bifurcated stigmas.

White oldfield aster - Symphyotrichum pilosumPhoto 5:  Ends of branches and secondary branches bear acicular leaves and bracts that transition directly to the acicular phyllaries.  Note the pubescent branches and ¾-inch daisy-like flower heads.

White oldfield aster - Symphyotrichum pilosumPhoto 6:  The disk flowers changes from yellow to reddish with age.  Note the many acicular leaves and bracts below flower heads

With fertilization, ray and disk flowers produce 1-seeded achenes topped by tufts of white hairs (pappus).  Achenes, about 1/16-inch long and dispersed by wind, are slightly flattened and lightly ribbed.

White oldfield aster - Symphyotrichum pilosumPhoto 7:   Composite flower heads have pistillate ray flowers and perfect disk flowers.  Ovaries indicated by “x’s”.  Stigmas of ray flowers indicated by red arrows while those of disk flowers indicated by yellow arrows.  Stamens indicated by blue arrows.  Pappus indicated by white arrows.

Asters are important nectar and pollen sources for many insects in the fall.  White oldfield aster may not be suitable for small gardens due to large size and tendency to readily spread by seed.  Removal and disposal of seeds before maturity lessens degree of spreading.

Several other native Arkansas asters have white flower heads and may get confused with white oldfield aster.  Wreath aster (S. ericoides), typically found in tallgrass and blackland prairies of western Arkansas, tends to be about 2 feet tall and bushy with smaller more closely spaced leaves; in addition, flower heads have fewer ray flowers.  White woodland aster (S. lateriflorum), known from throughout the state, has narrowly lanceolate leaves, prefers shadier and usually moister woodlands, has smaller flower heads with fewer ray flowers, and the pubescence tends to be limited to stems (although the mid-vein on the underside of leaves may be hairy, as well).  Bottomland aster (S. ontarionis) has abaxial side of leaves uniformly soft pubescent, upper leaves and bracts that are broader and more leaf-like, and is strongly rhizomatous; it occurs in lowlands of eastern Arkansas.  Tall white aster (S. lanceolatum), found scattered throughout much of the state in moist woodlands and disturbed areas, has mature leaves that are glabrous with wedge-shaped bases and stem hairs in lines, and it lacks the numerous small leaves and bracts found on upper branches of white oldfield aster.

White oldfield aster can be distinguished by a combination of characteristics: It 1) prefers drier and often more disturbed habitats, 2) has new basal growth of oval to elliptic leaves, 3) has evenly pubescent stems, and 4) has leafy fascicles during mid-summer growth.

Article and photographs by ANPS member Sid Vogelpohl

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