Know Your Natives – Wreath Goldenrod

Wreath goldenrod (Solidago caesia) of the Aster or Sunflower (Asteraceae) family is one of the smaller goldenrods that occur in Arkansas. In the U.S., it is found from Texas to Wisconsin and thence east to the Atlantic and Gulf Coasts. In Arkansas, it occurs across the state except for portions of the Mississippi Alluvial Plain and West Gulf Coastal Plain. The genus name is from Latin for “to make whole” or “to heal” in reference to purported health benefits derived from some species of the genus. The specific epithet, also from Latin, for “slate blue” in reference to stem color. Other common names include blue-stem goldenrod and woodland goldenrod.

Wreath goldenrod, a plant of mesic soils in upland deciduous woods, well-drained lowlands and bluff areas, is a herbaceous perennial that propagates by seed and rhizomes. Plants that have a half-dozen or more compact-growing stems are probably growing from a caudex supported by many long, slender, white, radiating, rope-like roots. While single-stem plants are probably growing from a rhizome’s tip or from node junctions along its length. The white, near-surface, stubby rhizomes are slow growing so that non-aggressive colonies may develop.

Stems, a light green when young, typically become bluish to purplish (on the sunny side) with an overcast of whitish bloom (i.e., a thin, waxy coat). The smooth, slender, terete stems, reaching 3 feet long, are ascending and arching, but frequently stems become reclined. Stems typically have a half-dozen or so axillary lateral branches mid-stem, well below the tip. Lateral stems, with widely varying length to about 1 foot long, have the same appearance as primary stems. The lower portions of primary stems tend to be straight, while distally the more slender portions are slightly zigzagged. Lateral stems tend to be slightly zigzagged their entire length. Individual stems that have lateral stems appear rather “skeletal” due to the spacing of the rather sparsely leafed lateral stems. All stems are mostly glabrous (hairless).

Wreath goldenrod - Solidago caesiaPhoto 1: Current-year stems grow from tips of rhizomes as new rhizomes emerge along their length. Stub of a previous-year stem can be seen at lower center. Photo October 24.

Wreath goldenrod - Solidago caesiaPhoto 2: Leaves of springtime stems have wide serrations. Minor marginal pubescence can be seen on lower portion of several leaves. Photo March 5.

The alternate leaves of wreath goldenrod, randomly arranged around the stems, are dark green adaxially (above) and a lighter green abaxially (below). Stem (cauline) leaves vary from broadly lanceolate below, to lanceolate at mid-stem, to narrowly lanceolate distally. They measure up to 5 inches long and ¾ inch wide, become gradually smaller toward the apex and even minute along lateral branches within the inflorescence (see below). Cauline leaves gradually taper to an acuminate tip and a sessile or nearly sessile base. Most leaf margins are serrated, with teeth of basal leaves wider and less pointed and those of cauline leaves increasingly acute and sharply pointed. Uppermost small cauline leaves (½ inch long and ⅛ inch wide and smaller) may be entire. Leaves are smooth and nearly glabrous, with minor marginal pubescence at the base. All leaves in the upper portion of the plant subtend a lateral stem or inflorescence (see below). Basal leaves drop off as the plant approaches flowering, and lower cauline leaves, if dry conditions occur, drop off as well during flowering.

Wreath goldenrod - Solidago caesiaPhoto 3: This plant has a dozen stems growing from a central caudex. Photo March 26.

Venation is pinnate. Veins of the adaxial surface are the same color as the leaf blade while, on the abaxial surface, the midrib and secondary veins are a light green. The midrib of the adaxial surface is suppressed while secondary veins may be slightly suppressed. Tertiary veins of upper surface are obscure while tertiary veins of lower surface are a dark green color such that a reticulated pattern is easily seen.

The inflorescence of wreath goldenrod, appearing for about a month in mid-fall, consists of small terminal and axillary clusters of composite flower heads. Flower heads reach anthesis from distal ends of stems, progressing downward. Clusters consist of 2 to 9 loosely arranged flower heads in short racemes. The number of flower heads in clusters generally decreases from stem apex, downward. All flower heads in a cluster reach anthesis at the same time and a fair number of clusters along a stem blooms at the same time, thus producing an arching wreath-like appearance. In cases where racemes appear to be especially long, one is actually seeing a very short lateral stem with tiny leaves, with each leaf subtending a flower head or two. Flower heads, drawn to sunlight, become secund (arranged along one side).

Wreath goldenrod - Solidago caesiaPhoto 4: Arching stems often recline. Flower clusters become oriented toward sunlight. Sunny sides of stems become bluish to purplish with age. Photo October 15.

Clusters are composed of up to ten or so tiny, bright yellow, loosely arranged composite flower heads. About ¼ inch long (including peduncle), heads comprise three to four pistillate (no stamens) ray florets surrounding up to eight or so perfect (stamens and pistils) disk florets. Ray florets have broadly oblong ligules (the flat, strap-shaped, laterally extended part of a ray flower), with several pleats and an apical notch, as well as slender styles with pointy-tipped, bifurcated stigmas. Disk florets are tubular with acutely triangular flaring lobes, and five stamens with short filaments and anthers, fused into a ring, that clasp the developing slender style. As the style emerges from the ring of anthers, it pushes out and exposes their pollen, to be carried away by pollinating insects. Anthers then wither, becoming white. Once fully exserted, the pair of linear stigmatic surfaces divides and becomes receptive to pollen, typically from other flowers–and most productively, from flower heads on other plants. (There is, nevertheless, much self-pollination in the sunflower family.)

Wreath goldenrod - Solidago caesiaPhoto 5: “Cluster” at left is composed of flower heads subtended by tiny leaves. Orange arrow indicates flared corolla lobes of a disk floret. Red arrow indicates style of a ray floret. Lavender arrow indicates anthers of a disk floret. White arrow indicates emerging style of a disk floret surrounded by ring of shrunken, whitened anthers. Photo October 17.

Wreath goldenrod flower heads are set in cup-like involucres composed of spirally arranged, tightly imbricated, oblong bracts (phyllaries). Heads have very short peduncles attached to short rachises so that racemes have a cluster-like appearance. Phyllaries transition below to tiny pedunculate bracts.

Wreath goldenrod - Solidago caesiaPhoto 6: Involucres are composed of elongate, imbricated phyllaries that transition into bracts along peduncles. Note dark green tertiary venation of lower side of leaves and marginal pubescence at leaf bases. Photo October 17.

Fertilized florets produce flattened, 1/16-inch-long, minutely pubescent, elongate achenes (often termed cypselae in this family–single seeded, indehiscent, nutlet-like fruits), each topped with a pappus of silvery hairs. Dispersal is by wind.

This fall-blooming goldenrod species would work well in an open woodland setting that has mesic soil. Among the goldenrods, it is a more dainty species with smooth leaves and stems. Bright yellow clusters of flower heads are showy and the plant’s open structure is attractive. It is not aggressive. As with all goldenrods, wreath goldenrod attracts a variety of small insects and butterflies. Fall allergies, blamed on goldenrods, are primarily caused by ragweeds (Ambrosia spp.), wind-pollinated members of the same Sunflower family.

Wreath goldenrod is one of 28 species of goldenrods (some with additional subspecies or varieties) known to occur in Arkansas, of which two other species have somewhat similar flowering characteristics: zigzag goldenrod (Solidago flexicaulis) and Ouachita goldenrod (Solidago ouachitensis), both of rather limited occurrence in the state. Zigzag goldenrod can be distinguished by its significantly wider to oval petiolate, heavily serrated leaves and its non-glaucous green zigzag stems. Ouachita goldenrod, quite similar to wreath goldenrod and occurring only on north-facing slopes of the Ouachita Mountains, can be distinguished by its larger leaves on unbranched, more upright stems, non-secund flower clusters, and composite flower heads each with only one ray floret.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Obedient Plant

Obedient plant (Physostegia virginiana*) of the Mint (Lamiaceae) family is an attractive plant with showy late summer to early fall flowers. The genus name is from Greek words for “bladder” and “cover” in reference to the inflated calyx that covers maturing fruit. The specific epithet refers to the type locality, Virginia, the provenance of the specimen originally described by Linnaeus. This species occurs from Texas to North Dakota, thence eastward to the Atlantic and Gulf coasts, along with scattered (and perhaps introduced?) occurrences in New Mexico, Utah and Montana. In Arkansas, obedient plant occurs throughout much of the Interior Highlands of the Ozarks, River Valley and Ouachitas, along with scattered occurrences on Crowley’s Ridge and several south-central Coastal Plain counties. The common name “obedient plant” refers to the plant’s flowers obediently remaining to one side when pushed. Another common name is false dragonhead, from similarity to species of Dracocephalum (not found in Arkansas). Obedient plant occurs in sunny prairies, glades and partially sunny woodland openings, in moist to wet, fairly well drained, fertile soils.

Obedient Plant - Physostegia virginianaPhoto 1: Established plants begin to produce basal leaves in mid-winter. Photo – February 20.

Obedient plant is a glabrous (hairless) herbaceous perennial with radiating, shallow, whitish roots and many segmented rhizomes (in some forms*). Rhizomes terminate in a bud or two that will produce clonal stems the following spring. Shiny, dark green, stout stems, to 3 or more feet tall, are four sided with prominently raised, rounded corners. Decussate (alternating at 90 degree angles) leaves and branches, originating between the corners, are typically in matched pairs. Between leaf and branch pairs, stems appear segmented. Segments may be up to 1½ inches long lower on the stem and to ½ inch long higher up. Each stem segment is straight and equidimensional except for a short, enlarged, lighter green portion immediately below the next higher leaf or branch pair. Plants in less sunny areas may have many branches while those in less sunny sites or less fertile sites may be unbranched. The stout stems are erect and tough, but the entire plant may recline under weight of the inflorescence. With drying soils, lower leaves may drop, while flowering continues.

Obedient Plant - Physostegia virginianaPhoto 2: This pair of stems was produced by one rhizome (extending off to the lower left). Current-year rhizomes and rhizome buds can be seen along with a vegetative bud (between the stems). Rhizome roots emerge at lines of segmentation (nodes). Stem bases are ¼ inch across. Photo Sept 29.

Leaves, dark green above and light green below, are lanceolate with very gradual tapers from mid-leaf to the acuminate apexes and sessile bases. Leaves of large plants tend to be broadly lanceolate (to oblanceolate) to 5 inches long and 1 inch wide, while leaves of smaller plants are narrower. Leaf margins along the distal half of leaf have sharp, well-spaced serrations with tiny prickle-like tips, while serrations lower on leaf gradually reduce in size toward the stem. Leaf axils that are not subtending a branch or floral spike have rudimentary buds that can break dormancy if a distal portion of the plant is broken off.

Mature stem leaves are pinnately veined, with secondary veins unnoticeable on the upper side and slightly noticeable below. The light green upper midvein is channeled. The lower midvein is whitish green and strongly expressed. Secondary veins arch off the midvein and become parallel to the margins before fading away.

Obedient Plant - Physostegia virginianaPhoto 3: In this sunny site, the plant has many branches, each of which will produce one or more terminal floral spikes. Photo Jun 16.

Floral spikes with sessile flowers terminate the main and secondary branches and also grow directly from leaf axils. Blooming occurs for a month or more from late summer into early fall. Terminal spikes tend to be straight while lateral spikes curve upward. Lanceolate, decussate bracts, with entire margins, are widely spaced along the spike below and become tighter above. Lowermost bracts may subtend rudimentary buds while bracts along most of the spike subtend individual flowers. Bracts, at anthesis, are about half as long as calyxes (see below). Flowers are sessile (no pedicels). Terminal spikes may be 8 inches long with as many as 100 flowers, while lateral spikes are shorter with correspondingly fewer flowers. Flowers on the main stem and lateral branches reach anthesis at the same time, with flowering proceeding along the spike from base to apex. Individual corollas are open for several days and then drop from the receptacle, leaving behind the calyx and developing fruit.

Elongate, round-tipped buds open into puffy, light pink to lavender (sometime white) corollas that are up to ½ inch wide and 1¼ inches long. Corollas have a constricted, laterally flattened base set within a relatively small (to ¼ inch long and ⅛ inch wide), conical, 5-lobed calyx. From their constricted base, corollas abruptly flare into a broad, puffy tube that narrows slightly at the throat’s broad opening. Corollas have an arching “top-rib” along the proximal two-thirds, which strengthens the rather flimsy structure and provides for attachment of stamens (see below). The throat opening has a 3/8-inch-long projecting, slightly hooded rounded upper lip and a half-as-wide recurved lower lip with two small lateral lobes and a broader central lobe. Flower color is more intense in the areas of the lobes and along the top-rib while fading elsewhere, including the throat which is marked with a splatter of dark purplish spots. At anthesis, the length of the calyx is longer than the subtending bracts.

Obedient Plant - Physostegia virginianaPhoto 4: Anthesis proceeds from spike base to spike apex. Note the relative length of bracts and calyxes along the spike. (A green lynx spider [Peucetia sp.] can be seen at the base of the spike. It is a hunting spider, often preying on flower-visiting insects.)

Flowers have four straight, slender stamens and a straight,  slender style. Stamens are adnate (attached) to the underside of the corolla’s top-rib (see above) with a side-by-side pair positioned to either side of a central style that is held against the top of the throat by the stamens. Anthers dangle just below the outer edge of the upper lip with a divided (bifurcated) stigma in between and slightly farther out. The two-lobed anthers, when releasing pollen, have a circular appearance (similar to a horse’s hoof). Filaments have soft shaggy hairs (villous) on their upper portion. With fertilization, a flower produces four dull brown, smooth 1-seeded nutlets with rounded “sides” and two angled sides. Nutlets, less than ⅛-inch long, are dispersed by gravity.

Obedient Plant - Physostegia virginianaPhoto 5: Flowers have a bifurcated stigma with a longer upper portion that angles up while the lower portion angles sharply down. Note the two-lobed anthers and villous filaments.

Obedient Plant - Physostegia virginianaPhoto 6: Lower flowers have dropped off as upper flowers bloom. A bumblebee fits snugly into the throat, so that there is an excellent chance that pollen will be deposited on its back. The style connects to a tiny 4-lobed ovary deep within the calyx.

Obedient plant is an attractive wildflower, ideal for a sunny to partially shady garden or natural area with moist to mesic soil. However, in a preferred habitat, this plant can spread aggressively from rhizomes. Plants may need staking when in bloom to remain erect and seeded spikes may need to be removed to better control plant spread. The very attractive flowers persist for a month or more in late summer into early fall. It is favored by hummingbirds, bumble bees and carpenter bees. (Carpenter bees are not pollinators because they “steal” nectar by cutting through the base of the flower.)

Other species of the same genus in Arkansas are: narrowleaf obedient plant (Physostegia augustifolia), foxglove obedient plant (Physostegia digitalis), and slender obedient plant (Physostegia intermedia). Physostegia virginiana can be distinguished by the combination of its relatively late flowering time and wider leaves with sharply toothed margins. The most similar species is Physostegia angustifolia, but it has narrowly lanceolate leaves (usually less than ½ inch wide) and primarily blooms in late spring to early summer.  Physostegia digitalis also has wider leaves, but they are less toothed and their bases distinctly clasp the stem.

  • Physostegia virginiana has multiple forms of which two have been classified as subspecies, namely, Physostegia virginiana subsp. praemorsa and Physostegia virginiana subsp. virginiana. Subspecies praemorsa is said to have larger flowers, to form clumps, and to favor upland prairies and glades in comparison to subspecies virginiana which is said to have smaller flowers, to form colonies via rhizomes, and to favor wetter bottomlands and streambanks. Wild Arkansas plants have all been classified as subspecies praemorsa by most authorities, but there may be several different forms in the state, and it remains unclear as to what names best apply (perhaps both subspecies listed above, perhaps varieties or species synonymized under those two, or perhaps as yet undescribed entities).  To confound the issue, the species is commonly cultivated and cultivars may escape into the wild.  The species is in need of further field and taxonomic study.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Wood nettle

Wood nettle (Laportea canadensis) of the Nettle (Urticaceae) family is a perennial forb cloaked in needle-like, translucent, painfully stinging hairs. The genus name honors French naturalist Francois Laporte who studied the fauna of North America in the 1840s. The specific epithet refers to Canada, the locality from which Linnaeus’s type specimen was collected. In the U.S., the species occurs from Louisiana to Oklahoma to North Dakota and thence across the country to the Atlantic and Gulf coasts. In Arkansas, it occurs statewide except for portions of the Mississippi Alluvial and West Gulf Coastal Plains. Wood nettle occurs as an understory species in mesic to wet habitats with fertile soils associated with wooded seeps, riparian forests and bottomlands. It is also called stinging nettle*.

Wood nettle spreads freely in its preferred habitat from seeds and rhizomes so that large colonies may develop. In the spring, erect light green stems emerge that have alternate tissue-thin bracts on their lower six inches, below the leaves. The erect, unbranched, terete stems are slightly zigzagged from one leaf base to the next. Stems, remaining light green to medium green throughout the growing season, reach a height of 2 to 3 feet, with well-spaced leaves. The hollow hairs (trichomes) contain various chemicals which, upon touch, are injected into unwary hikers, producing a burning or itching sensation that lasts for 15 or more minutes. Blooming in mid-summer, wood nettle has staminate and pistillate flowers on the same plant (monoecious), borne in separate panicles to 4 inches long.

Wood nettle - Laportea canadensisPhoto 1: Clump (5 inches wide) includes several plants with intertwined roots. White pointed buds, for next growing season, can be seen at base of current-year stems. Round holes are scars from previous-year stems.

Leaves are alternate (other Arkansas nettles have opposite leaves). The simple leaves are up to 8 inches long, including the 2½-inch petiole, with the largest leaves occurring mid-stem. Leaves are ovate, to 3 inches broad. The upper leaf surface, slightly rugose at maturity, is a deep green, while the lower surface and petiole are light green. Leaf margins are coarsely serrate with triangular teeth, except for the rounded to weakly wedge-shaped base. Leaf tips are attenuate, longer than the lateral teeth. Venation is pinnate, with midvein, secondary and tertiary veins of the upper surface depressed and veins of the lower surface strongly expressed in round-relief. Long stinging hairs are scattered around the petiole as well as along principal veins of the lower surface. Scattered, stubby hairs are spread across the upper surface. Lower leaves tend to drop off as the growing season progresses.

Wood nettle - Laportea canadensisPhoto 2: Wood nettle is an understory species in rich, moist areas. Alternate leaves have long petioles and coarse serrations. Photo April 26.

Wood nettle - Laportea canadensisPhoto 3: A monecious species, female panicles appear at stem apex (light green) while male panicles (whitish) appear lower down the stem. Photo September 2.

The pistillate flowers (without stamens), in one to several slightly zigzagged panicles, grow from the stem apex (where leaves are closely spaced) and, sometimes, from the next-lower one or two leaf axils. The panicles, erect early, become more horizontal as they mature. Panicles consist of a half-dozen or more straight secondary lateral cymes, set at about 55 degrees off the main axis, along with a terminal group of flowers. Lateral cymes are also set at about 55 degrees from their axis and alternate from side-to-side. Cymes consist of a series of short alternate peduncles, each of which has up to to eight or so tiny (1/16 inch wide) downward-facing flowers. Flowers attach to flat somewhat triangular flange-like pedicels that become more apparent as fruits mature. Flowers have two noticeable sepals positioned at opposite sides of the ovary. Ovaries are tipped by long slender styles which twist skyward so that pistillate panicles have a wispy appearance. The entire panicle is a light green and cloaked with stinging hairs.

Wood nettle - Laportea canadensisPhoto 4: Pistillate flowers hang downward and long wispy styles reach skyward. Each flower attaches to a flange-like pedicel.

Wood nettle - Laportea canadensisPhoto 5: Display showing underside of a pistillate panicle. Long tapering styles point skyward. Note various stages of ovary development. Darker green patches “on” the ovaries are the sepals.

Below the female inflorescence, several leaves subtend the staminate flowers (without pistils). Structure of the staminate inflorescence is much like that of the pistillate inflorescence; however, staminate panicles are horizontal to drooping. Staminate panicles, extending out from the main stem to about the base of the leaf blades, are light green to whitish, with few stinging hairs. The tiny male flowers (⅛ inch corollas) face skyward. Flowers have five sepals (no petals) centered by five stamens and an infertile central column, actually a rudimentary ovary. They are light to whitish green with a dark green rib centered on each sepal. Stamens have white filaments and anthers that extend outside the corolla. Once pollen has been released, staminate panicles wither.

Wood nettle - Laportea canadensisPhoto 6: Display showing staminate panicle. As shown, only a few flowers are at anthesis. Flowers have sepals with dark green midribs and white filaments and anthers.

Pollination is by wind. With release of pollen, staminate panicles dry, and developing ovaries on the pistillate panicles quickly extend out from the closely hugging sepals. At first green, the fruit becomes a shiny black color. Mature fruits (achenes) are flattened, smooth and ovoid with thickened centers and two points. One point is where the style attached to the ovary while the other point is where the ovary’s base attached to the pedicel. As the plant fades in the fall, the achenes drop.

Wood nettle - Laportea canadensisPhoto 7: With achenes nearing maturity, the plant is approaching dormancy. Note the flanged pedicels and dried staminate panicle lower on main stem. Round crinkly objects in lower left corner are seed heads of yellow wingstem/ironweed (Verbesina alternifolia). Inset, an underside view, shows achenes clasped by the sepals.

Wood nettle, although an interesting plant, would not be desirable for a garden due to its stinging hairs and propensity to spread widely in its preferred habitat. However, nettles are important host plants for butterflies such as the Question Mark and Red Admiral, along with a number of moths.

  • Wood nettle (Laportea canadensis) is the only species of the genus in Arkansas. However, other native nettles found in the state may be confused with wood nettle, namely stinging nettle (Urtica chamaedryoides), stinging nettle (Urtica gracilis), clearweed (Pilea pumila), and false nettle (a.k.a. bog hemp) (Boehmeria cylindrica). Of these four, only U. chamaedryoides and U. gracilis have stinging hairs; however, their leaves are opposite and their inflorescences are completely different. The potent stinging nettle, Urtica dioica, is not currently reported in the state, but it too has opposite leaves.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Gum plant

Gum plant (Grindelia lanceolata) of the Sunflower (Asteraceae) Family is a viscid (sticky) plant with thick leaves. The genus name recognizes the early 19th-century Russian botanist, David Grindel. The specific epithet refers to the lance-shaped leaves. In the U.S., the species ranges from New Mexico to Ohio and Kentucky, as well as Wisconsin and Connecticut. In Arkansas, it occurs throughout much of the Ozarks and Ouachita Mountains. Habitat preference is sunny areas with rocky soils associated with limestone, sandstone or shale, where soils are generally dry to seasonally moist, especially glades, prairies and roadsides. Other common names include narrow-leaf gumweed, spiny-toothed gumweed and fall gumweed.

Gum plant is a short-lived perennial with fibrous roots along with one or several woody rambling fairly short taproots. The entire plant is glabrous (without hairs) and may feel viscid due to resinous pores. A mature plant has a half-dozen or more mostly erect, stiff, herbaceous stems. Stems, to 3 feet tall, typically have a half-dozen or more branches in their upper two-thirds. These branches, in turn, typically have 0 to 4 secondary branches. The slightly striate stems are light green to reddish in their actively growing upper portions while lower portions of a growing plant become tough and brown. All branches, which are arranged alternately, terminate with a solitary flower head. At the end of the growing season, erect dead stems may persist, even to the end of the next growing season.

Gum Plant - Grindelia lanceolataPhoto 1: Spring leaves of this mature plant in a highway right-of-way are basal-cauline leaves. Tough, hardened stems from previous year’s growth remain. Photo March 4.

Generally, the simple, alternate and ascending leaves are lanceolate with prominently serrate margins and acuminate leaf apexes. Marginal teeth and leaf apexes are apiculate. Some plants may have entire leaves, especially near the inflorescence; these tend to be twisted with undulated margins. The sessile, thick leaves feel slightly to moderately viscid. Upper and lower leaf surfaces are medium green with lighter green mid-veins. Mid-veins are weakly expressed and secondary pinnate veins are obscure. Pores may be evident on upper and lower leaf surfaces. Leaf size gradually decreases from 4 inches long and ¾ inch wide at stem base to one inch or less long and ⅛ inch wide at stem apex. When soil dries, lower leaves die while new apical growth and flowering continues.

Gum Plant - Grindelia lanceolataPhoto 2: Leaf shape changes from stem base to stem apex (leaves have been flattened for photo). Cluster at upper left is a growing tip prior to branching of stem. Leaves of stem segment have been removed, but alternate leaf arrangement is evident. Photo April 29.

Gum Plant - Grindelia lanceolataPhoto 3: Leaf margins may be entire. Height of branches exceeds height of central stem. Older stems harden and become brown. Photo August 5.

Composite flower heads, when still in a tight bud, have a spherical burr-like appearance due to an involucre of closely spaced, linear to lanceolate bracts. With anthesis, as receptacles assume a shallow bowl-shape, the burr-like appearance becomes hemispherical. The bracts, up to ½ inch in length and 1/16 inch wide, have short flattened bases while the remaining length is terete (round) in cross-section. Bracts, extending outwards and upwards, are pliable with sharp apiculate tips.

Flower heads, with bright yellow ray and disk florets, reach anthesis in mid-summer with bloom period extending for a month or so as flowering at tips of newer branches continues. A mature flower head, to about 2 inches wide with a ¾ inch central disk, has about 30 to 35 ray florets and several hundred disk florets. Ray florets have strap-like ligules, to ¾ inch long and ⅛ inch wide, that are widest at their mid-section with a very gradual narrowing to a tapered base and apex. Flower heads are more viscid than other parts of the plant, and botanists have a devil of a time trying to dry these heads when preparing pressed specimens.

Gum Plant - Grindelia lanceolataPhoto 4: Thick lanceolate leaves are twisted. Involucres are spiky with apiculate bracts. Branches terminate with a single flower head. Photo August 5.

Gum Plant - Grindelia lanceolataPhoto 5: Display shows 1) flowerhead with disk florets beginning to open, 2) bottom of a bracteate receptacle and 3) a divided flowerhead showing the receptacle in cross-section and ovaries.

Ray and disk florets are both fertile, with ray flowers being pistillate (no stamens) and disk flowers being perfect. The tiny, tightly compressed disk florets (⅛ inch long) are tubular, with five triangular lobes; five elongate stamens have fused (connate) anthers that surround the style. Like a plunger, the style emerges from the circle of anthers, pushing the pollen out, where it becomes available for contact with pollinating insects. As the pollen is dispersed, the stigmas then split apart (bifurcate) to expose two elongate receptive stigmatic surfaces. Disk florets of the composite head flower centripetally, from the outside in–the oldest florets thus are at the periphery of the head, the youngest (often still in bud) are in the center.

Gum Plant - Grindelia lanceolataPhoto 6: Pollen-tipped anthers are exserted from younger florets in central portion of flower head, while around the perimeter exserted stigmas of older florets have bifurcated to expose stigmatic surfaces.

A fertilized floret produces a cypsela (indehiscent fruit from an inferior ovary, often called simply an achene). The light brown, smooth achenes are flattened and oblong with rounded bases and cut-off apexes. Apexes bear two straight smooth awns, often exceeding length of corolla tubes, which drop off as fruits mature. Achenes have a central rib on their smooth sides and thin lateral margins.

Gum Plant - Grindelia lanceolataPhoto 7: Fruiting head: With flowering completed, achenes fall from the receptacle, leaving only the phyllaries (bracts) of the involucre. A discarded awn is partially hidden by an achene. Photo October 15.

Gum plant, a short-lived perennial, may be an appropriate choice for a wild garden. It has thick attractive leaves and bright yellow flower heads with burr-like involucres. However, with dry soils, lower leaves die and the plant becomes “leggy”. Thinning of seedlings may be required. Gum plant flower heads appear similar to those of many yellow composites, especially the taller woodland sunflowers, whose larger heads are in bloom at the same time.

In addition to Grindelia lanceolata, two other gum plants native to the south-central and western U.S. have been collected in Arkansas (though they may have been introduced to the state); namely, Spanish gold (a.k.a. wax gum plant or waxweed; Grindelia ciliata [or Prionopsis ciliata]) and curly-cup gum plant (Grindelia squarrosa). Grindelia ciliata, in comparison to G. lanceolata, has flattened, elongate-triangular floral bracts that are straight and leaves that are broader with margins spiny rather than serrated. Grindelia squarrosa, in comparison to G. lanceolata, has stubbier, sharply recurved floral bracts and shorter, wider leaves with less prominent serrated margins.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Hairy Blazing Star

Hairy blazing star (Liatris hirsuta*) of the Aster (Asteraceae) family has vibrant violet to lavender flowers, typical of many species in the genus. In the U.S., hairy blazing star is reported from Texas and northward to Nebraska and Iowa, with scattered reports in Mississippi, Alabama, and Georgia. In Arkansas, it is found throughout much of the state except for lowlands of the Mississippi Alluvial Plain and West Gulf Coastal Plain. The origin of the genus name has been lost. The specific epithet is Latin for “hairy”. Habitats consist of sunny rocky outcrops, glades and prairies with fairly well-drained soils. Other common names include hairy gayfeather (based on flower appearance) and Rydberg’s blazing star (described by Per Axel Rydberg in 1931).

Hairy blazing stars have globose corms with tops covered with short peaks that served as the bases for previous stem growth and a rounded to knobby bottom from which long skinny white roots grow. New growth buds, appearing across the corm’s top in mid-winter, produce only tufts of basal leaves or stems that have same-appearing “basal” leaves. Stems, unbranched and terete with a length of 2 to 4 feet, are light green with slightly raised darker green ribs that extend down from leaf bases. The slender stems, to about ¼ inch in diameter, have a slight taper from base to apex. Stems, not having “extra” girth at point-of-attachment to the corm, typically become reclined unless supported by other stems or other vegetation. Stems and leaves are roughened by straight, spreading hairs.

Hairy Blazing Star - Liatris hirsutaPhoto 1: This corm, with eight stems, is 3 inches in diameter and 2 inches thick. Fibrous roots grow from knobs at the base. Photo early August.

All leaves are linear to linear-lanceolate with the largest (to 8 inches long and 1/8 to 1/3 inch wide) being basal-cauline leaves. Size of cauline leaves gradually decreases up stem, with uppermost leaves being ¾ inch or less long. Pliable spring leaves become stiff, rough and twisted as the growing season progresses. Leaf color is medium to dark green above and below, with the upper and lower midvein being the same light green as the stem. Upper leaf blade to either side of the midrib tends to be up-turned (involute), especially at the entire (smooth), somewhat crinkly margins. Venation, largely obscure, is parallel to leaf margins with the upper midvein slightly expressed while the lower midvein is slightly depressed. Pubescence occurs on upper and lower surfaces of leaves and along leaf margins (ciliate pubescence).

Hairy Blazing Star - Liatris hirsutaPhoto 2: In this sunny, rocky habitat, new stems become apparent above their basal leaves. Previous year’s dead stems are splayed around the new growth. Photo early May.

Cauline leaves, positioned all around the stem, are sessile while lowermost leaves are also clasping. Leaf separation decreases from ½ inch (lower of stem) to ¼ inch (higher on stem). Cauline leaves are slightly narrowed near their bases and have a gentle taper to their acute apexes.

Inflorescence of hairy blazing star, in mid to late summer, consists of composite flower heads. Along with a solitary flower head at stem apex, additional lateral heads grow from upper leaf axils. Generally, wherever the lowermost lateral flower head occurs, almost all higher-up leaf axils also produce flower heads. Depending on age of plant and its habitat, a vigorous stem may have 40+ heads attached to its upper 18 inches. Flower heads mature and reach anthesis from stem apex, downward. Lower flower heads of a vigorous plant may be on short branches with a leaf or two (or even a lateral flower head or two), while higher heads may be on short pedicels attached to the stem or may be attached directly to the stem.

Flower heads of hairy blazing star have disk florets only (discoid head); ray florets are absent. Heads have tightly bound, spindle-shaped involucres that are to about ¾ inch long and ⅜ inch wide. Involucral bracts (phyllaries), in six to eight overlapping (imbricated) series and of unequal size, are oval to oblong, spreading, and with acutely-tipped, recurved apexes. Inner phyllaries are smaller, with shorter recurved tips. Lower portions of phyllaries are firmly pressed together, but can be separated with little effort. Phyllaries, mostly glabrous, have ciliate margins. Involucres, which feel hard and bristly, may be purplish in sunnier sites.

Hairy Blazing Star - Liatris hirsutaPhoto 3: The flower heads do not have ray flowers. In this photo, the terminal flower head has passed anthesis. Pubescence of stem, leaves and involucres can be seen. Photo late July.

Disk florets, 10 to 20+ per head and ⅖ to ⅗ inch long, have corollas that are a vibrant violet to lavender color. At anthesis, the corollas each have five short lobes that flare outward from long tubular bases. Pistils have a bifurcated style that exceeds the length of the tube. The “arms” of the style, joined inside the tube, twist-about in random, rather wispy fashion. Stigmas are not noticeable. Stamens, hidden within the floral tube and attached to the tube’s base, have long slender filaments with equally long and slender brown to purple anthers that split lengthwise to release white pollen. Corollas, set atop elongate inferior ovaries, are surrounded by a ring of long hairs (pappus) that are half the length of the tubes.

Hairy Blazing Star - Liatris hirsutaPhoto 4: Buds of the tubular florets have round-pointed apexes that flare open to expose five lobes. Styles are strongly exserted while stamens are hidden within the tube. Photo late July.

Hairy Blazing Star - Liatris hirsutaPhoto 5: Display of florets from bud to anthesis (right to left). Corollas and pappus attach to top of elongate ovaries. Inset shows ovary with pappus (left), style (right, removed from ovary), and anthers within cut-away corolla tube (center).

After the growing season, plants dry and involucres disintegrate. One-seeded, indehiscent, elongate fruits (cypselae), ¼ inch long, with fluffed-up pappus are dispersed by wind. The ribbed cypselae have flat tops with flared long hairs (pappus) and tapered bases. Fertilized and unfertilized cypselae have the same appearance, but fertilized cypselae are more firm.

Hairy Blazing Star - Liatris hirsutaPhoto 6: With involucre disintegrating, cypselae are set for wind dispersal. Photo mid-December.

For a garden or natural area, blazing stars should be welcome due to their long-lived nature, adaptability to rocky soils, their texture and strong flower color. Blazing stars are also good nectar plants for butterflies. Among the at least ten species and additional varieties native to Arkansas, are several that have a more upright structure and may fit better in a limited space. Of the other Arkansas species, the one most similar to hairy blazing star is scaly blazing star (Liatris squarrosa). The main characteristic that helps identify hairy blazing star is that the involucral bracts are spreading to recurved (instead of ascending to spreading) and outer bracts are shorter than inner bracts.

  • Some authorities classify this species as Liatris squarrosa var. hirsuta.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Fly poison

Fly poison (Amianthium muscitoxicum*) of the Bunchflower (Melanthiaceae) family, the only species in the genus, bears white flowers that change to green. The genus name originates from Greek words for “pure” and “flower”. The specific epithet is from Latin words for “fly” and “poison”. In the U.S., fly poison occurs from Oklahoma and Missouri across the Southeast and extending north into New York. In Arkansas, it occurs primarily in scattered Interior Highlands counties in roughly the northwestern half of the state. The name “fly poison” relates to early Americans’ use of the plant’s bulbs (crushed with a sweetener) to kill flies. Other common names include crow poison (used by Native Americans to poison crows) and stagger grass (causes grazing cattle to stagger). The plant is generally found in dry to moist open woodlands and prairies. Along with the bulb, other parts of the plant are also poisonous, although to a lesser degree.

Seedlings (monocots) have contractile roots which pull the bulb’s base several inches into the earth so that tops of bulbs are just below the surface. Numerous white fleshy roots, newly grown each year, splay in all directions from the reduced stem at the base of the bulb (basal plate). Mature bulbs, slender with a broader lower section, are to 2 inches long and to 1 to 1¼ inches wide. Tight clumps of bulbs may form as clonal bulbs develop off basal plates. Girth of bulbs increases as new concentric leaf bases (fleshy scales), terminated by a leaf, grow from the interior-center of the basal plate. Old leaf bases thin and dry on the exterior to form a papery tunic. Basal plates typically have one vegetative growth point, but a second point may develop.

In late winter, a bulb produces eight to a dozen new leaves as an upright rosette, surrounded by limp dead leaves and maybe a dead stem from the previous growing season. Leaves may reach a length of 2 feet at maturity. Leaves, a bright medium green, are broadly arched with the tips touching the ground. Leaf width, ½ to ¾ inches, is fairly uniform except for a widened base and a short-tapered cupped tip. In cross section, leaves are v-shaped with a channeled upper midrib and a sharply keeled lower midrib. Leaf margins are entire. Closely spaced veins parallel the straight, entire (undivided) margins. Leaves begin to fade in early August as fruit develop.

Fly Poison - Amianthium muscitoxicumPhoto 1: Leaf rosettes appear in late winter. Tips of leaves are cupped. Photo March 18.

Fly Poison - Amianthium muscitoxicumPhoto 2: This clonal group produced several rosettes of arching leaves. Upper mid-veins are channeled.

In early May, flowering stems, same color as leaves, rise above leaves from the center of leaf rosettes. A few bulbs of a colony each produce single, unbranched, erect stems. Glabrous stems grow to 3 feet tall and about ¼ inch wide, with three smoothly rounded sides. Stems have three or so widely spaced and clasping leaves on the lower half that transition into a half dozen or more closely spaced bracts on the upper half. Cauline leaves are helically (spirally) alternate. Lowermost cauline leaves may be 16 inches long and ¾ inch wide, while uppermost cauline bracts may be ⅛ inch long and 1/16 inch wide. These small cauline bracts extend to the base of a terminal raceme. The stem within the raceme (rachis), pedicels and flowers are white. The slender, straight pedicels are ½ to ¼ inch long, radiating outward slightly above horizontal. Racemes, changing from pyramidal to cylindric and bearing up to 100 flowers, are up to 3+ inches long and up to 1¾ inches wide. Flowers bloom from bottom to top of the raceme in sequential tiers. Racemes narrow slightly from base to apex due to higher flowers being slightly smaller and pedicels being shorter.

Fly Poison - Amianthium muscitoxicumPhoto 3: Flower buds are covered by cupped bracts that quickly shrink away from buds and become brown. Long, clasping cauline leaves can be seen on the taller stem. Photo May 6.

Fly Poison - Amianthium muscitoxicumPhoto 4: Racemes are pyramidal at first, but become cylindrical as upper flowers mature. Narrow stems hold flowers well above the leaves. Photo May 20.

Flower buds are subtended and covered by cupped floral bracts which quickly shrink and become brown as flowers approach anthesis. Flowers are about ⅜ inch wide. A flower has 6 cupped tepals (3 sepals and 3 petals), 6 stamens and a short pistil with three flared and pointed styles above a prominent, free-standing, 3-chambered ovary. Each chamber is round with a sharp tip, with the chambers joined along a central axis. Sepals and petals, are reflexed and have a similar appearance; however, sepals are slightly shorter and broader. Tepals, with little lateral overlap, have rounded apexes and broad bases. Stamens are widely flaring and spiky, with knobby pale yellow anthers. Viewed from the front, anthers are centered over the cupped tepals. The shrunken brown floral bracts still persist as fruits mature. The entire raceme, except for discarded anthers and floral bracts, becomes green as the blooming sequence moves upward. The entire now-green raceme persists, including tepals and spiky filaments and stigmas, until fruit reach maturity; however, racemes become brown as fruit matures in August.

Fly Poison - Amianthium muscitoxicumPhoto 5: The white stem, pedicels and flowers change to green immediately after flowers pass anthesis. Brown remnants of subtending cupped floral bracts are persistent. Photo May 20.

Flowers have 1-2 ovules in each chamber of their 3-chambered ovaries. With fertilization, the ovaries swell to produce a deeply 3-lobed, horned capsule, ⅜ inch long and wide. Typically only a small proportion of flowers produce seeds, and all the ovules of a flower seldom mature to seeds. Mature seeds have a thin, fleshy, shiny orange outer seed coat. An enlarged mature seed causes a split of its chamber from the tip to the inside-center. The seeds, measuring about 3/16 inch long, are rounded-oblong with a narrowed apex. The seed within the outer coat is stubby and rounded, white and smooth.

Fly Poison - Amianthium muscitoxicumPhoto 6: After flowers bloom in May, the green raceme persists into August when fruits mature. Inset shows a sterile flower (bottom), a flower with seeds removed from fruit (center) and a flower with seeds retained within fruit (upper).

In a partially shady, moist garden or natural area, fly poison would provide interest from late winter into late summer. It has attractive basal leaves and a prominent long-lived white to green raceme that later shows its colorful fruit. It is not aggressive and is avoided by deer. Care must be taken so that its parts, including the onion-like bulb, are not consumed by humans or animals.

Fly poison, prior to its fruiting stage, may be confused with death camas (Toxicoscordion nuttallii).

  • The specific epithet may be spelled “muscaetoxicum”. Amianthium muscitoxicum was previously classified as Zigadenus muscitoxicus and Chrosperma muscitoxicum. Previously assigned to the Lily (Liliaceae) family.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Green Milkweed

Green milkweed (Asclepias viridiflora) of the Dogbane (Apocynaceae) family, formerly of the Milkweed (Asclepiadaceae) family, is one of 14 Asclepias species found in Arkansas. It occurs across the U.S. except for six western states and five northeastern states. In Arkansas, it occurs throughout much of the state, except for lowlands of the Mississippi Alluvial Plain and the West Gulf Coastal Plain. The genus name is based on the Greek god of medicine (Asklepios, a.k.a. Asclepius). The specific epithet is from Latin for “green flowered”. Other common names include green comet milkweed, green-flowered milkweed, and short green milkweed (in comparison with “tall green milkweed”, Asclepias hirtella). Habitat preference is mostly sunny, mesic to dry conditions found in upland rocky glades and hilly prairies where it is not overshadowed by competition.

Green milkweed, typically found as isolated occurrences, is an herbaceous perennial with a straight taproot and one or two typically unbranched stems that reach a height of 2 or 3 feet. Stems, mostly erect, are a light to medium green, but may have purple shading. They are round in cross-section and densely covered with short, matted pubescence (tomentose). With sufficient moisture, apical stem growth continues well into mid-summer and short lateral branching may occur. Plants produce a sticky white sap like many (but not all) of the other milkweeds.

Leaves in lower portion of plants occur in opposite, decussate pairs, while upper leaves may be paired or alternate. Leaf spacing is fairly uniform along the entire stem, with separation being 1 to 2 inches. Leaves are short pubescent on upper and lower surfaces, 4 to 5 inches long and ¾ to 1½ inches wide (often larger leaves in wetter sites), and lanceolate to broadly lanceolate with tapering bases and apexes. The blade tends to be bowed-up on the edges and the entire margins irregularly wavy to undulating. Leaf blades, on short petioles (⅛ inch), extend horizontally at maturity. The margins have the same pubescence as the blade surface. Upper midribs are depressed; lower, light green midribs are expressed. Venation is off-set pinnate with secondary veins extending from midrib to near leaf margins where they connect into a single vein that follows the margin. With summer heat, venation becomes less distinct and leaves feel rough and leathery.

Green milkweed - Asclepias viridifloraPhoto 1: Lower leaves are in decussate pairs while later leaves may be in pairs or alternate. Photo May 30.

Inflorescence, in June into July, consists of umbels slightly below and between leaf pairs or opposite a single leaf (one umbel per leaf pair or per leaf). Depending on site conditions and weather, several to a dozen umbels may occur. Umbels have short, stubby peduncles that divide into many short, slender pedicels. Pubescence of stems extends onto pedicels. Umbels, with a convex “front” side, a flattened base and a round circumference (when viewed from the front), are down-bent (pendulous) and immobile. Umbels, with 20 to 80 tightly spaced flowers, are 1 to 2 inches wide. Pedicels are subtended by a pair of lanceolate bracts to ⅜ inch long.

Green milkweed - Asclepias viridifloraPhoto 2: Umbels attach to the stem between a pair of leaves or, with alternate leaves, opposite the leaf. Inset shows a plant with reddish umbels. Photo Jun 19.

Flowers of green milkweed at anthesis, ½ inch long and ¼ inch wide, are typically light green to light yellowish green, but may be reddish. Flowers each have five, ⅛-inch, narrowly triangular and strongly reflexed calyx lobes and five, ¼-inch, lanceolate, cupped and strongly reflexed corolla lobes that surround an upright corona. The corona surrounds a central flat-topped column that bears both 5 stigmatic surfaces and 10 pollinia (pollen packets). Pollinia occur in divergent pairs at the ends of threadlike “translator arms” joined to a “clip” that is positioned above each of 5 slits in the central column. The column is surrounded by 5 nectar-bearing, oblong hoods attached at its base. Access to each slit is located between each pair of hoods. When a bee collects nectar, its leg can slip through a slit to the clip which then snags onto the leg. As two pollinia are attached to each clip, upon visiting other flowers, the bee’s leg may insert a pollinium into a slit, where it comes into contact with a receptive stigmatic surface, breaks away from its translator arm, and effects pollination. Flowers have two prong-like, greenish white pistils, the tips of which fuse to the anthers to form the central column. Unlike most milkweed species, green milkweed corona hoods do not have horns.

Green milkweed - Asclepias viridifloraPhoto 3: A divided flower showing two bracts (long ones on left side), five calyx lobes (scattered), five petals (two upper and three lower in display), two pistils attached to pubescent pedicel, and a corona/column that has been cut for an interior and exterior view (upper right). Exterior view shows a clip (the tiny dark structure) above a minute line, the slit.

Green milkweed - Asclepias viridifloraPhoto 4: Umbels are stoutly peduncled, immobile and down-bent. Reflexed petals hide sepals while exterior bracts remain visible. Several pollinia are attached to the tips of the bee’s legs.

Green milkweed produces smooth, round (in cross-section) pods that are constricted and round-pointed at both ends and covered with short pubescence. Pods are 3 to 5 inches long with a width of ½ to ¾ inch. Numerous flat, round, brown seeds are attached shingle-style, in the lower portion of the pod, to a central rib-like placenta. Seeds bear long white hairs tightly pressed together in the upper portion of the pod. When pods become brown and dry, they split along one side (follicles) and hairs fluff-up in the breezes and individual seeds are pulled free, each with a buoyant tuft of long hair.

Green milkweed - Asclepias viridifloraPhoto 5: While pods are ascending, the pod’s stem remains down-bent. A monarch caterpillar hides below an upper leaf. Upper leaves of this plant are alternate. Photo August 27.

Green milkweed may be mostly unnoticed in a well-drained, sunny garden setting. However, this non-aggressive species would add interest when mixed with other more visible milkweed species and is a host plant for monarch butterflies and a nectar plant for bumblebees.

Green milkweed - Asclepias viridifloraPhoto 6: Green milkweed (Asclepias viridiflora) alongside butterfly milkweed (Asclepias tuberosa subsp. interior) in a garden setting .

Thirteen other species of the genus occur in Arkansas. Of these, six species can have greenish flowers (though some of these may be whitish, yellowish, or pinkish instead or in addition to greenish), namely green milkweed or spider milkweed (Asclepias viridis), tall green milkweed or prairie milkweed (Asclepias hirtella), curly milkweed or blunt-leaf milkweed (Asclepias amplexicaulis), whorled milkweed (Asclepias verticillata), savanna milkweed (Asclepias obovata), and narrow-leaf milkweed (Asclepias stenophylla). Green milkweed (Asclepias viridiflora) can be distinguished from all other Arkansas milkweeds except A. hirtella by its multiple lateral umbels and corona hoods without horns.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Clammy groundcherry

Clammy groundcherry (Physalis heterophylla) of the Nightshade (Solanaceae) family is one of eleven species (with one having two varieties) of the genus occurring in Arkansas, with a twelfth species currently being described new to science. It occurs naturally throughout much of the continental U.S., except for the far West. In Arkansas, this species occurs pretty much statewide (current gaps in distribution may be due more to specimen collection gaps than true distribution gaps). The genus name derives from a Greek word for “bladder” in reference to an enlarged calyx at fruiting. The specific epithet, from Latin, means “variably leaved”. Clammy groundcherry occurs in habitats ranging from open woodlands to prairies to disturbed areas in soils that may be poor to rich and dry to moist. “Clammy” relates to the feel of stems and leaves, more or less covered with glandular hairs.

Clammy groundcherries have a “parent” plant with a deep, slender, ropy taproot along with lateral roots 2 to 4 inches below surface that may be 4 feet or more long. In a selected specimen, the taproot was 3/8 inch in diameter while lateral roots were half that size. Lateral roots produce widely scattered stems (up to several feet apart) along their upper surface, as root-tip continues to grow. Stems growing from lateral roots remain attached to parent plant and do not develop taproots. The light tan taproots and lateral roots have a few relatively short, light-colored, fibrous roots.

Clammy groundcherry - Physalis heterophyllaPhoto 1: “Parent” plant on right has a ropy taproot from which lateral roots extend outward to produce a series of secondary stems (inset) without taproots.

New growth of this perennial originates from the tops of taproots (several inches below surface) and directly from horizontal roots (also several inches below surface). Plants grow to a height of 2+ feet, branching freely. The entire plant (except for flowers) is dull light green with stems and branches being a light yellowish green. Growth pattern consists of alternate leaves along straight stems near base of plant and, higher up, two leaves and a stem or two stems (or even three) and a leaf growing from a common point. Flowers grow from the center of the “groups-of-three”. For a relatively small plant, it has strong “architectural character” due to its open growth pattern, prominent branching and large upper leaves. Plants are structurally weak and become decumbent while new branches are ascending. Heavily pubescent stems are mostly round in cross-section, but lower portions of stems may become slightly ridged as they harden. Stem pubescence consists of intermixed long and short straight hairs, the latter gland tipped and producing the clammy texture. Branches of dead stems quickly disintegrate over winter, but lowermost portions of dead stems persists into spring.

Clammy groundcherry - Physalis heterophyllaPhoto 2: Stems have points where leaves and branches in groups-of-three originate. Heavy pubescence covers most of the plant. Previous year’s dead stems can be seen behind the green plant.

Leaves of clammy groundcherry are generally broadly heart shape (cordate) although some leaves, especially the lowermost, may be ovate. Margins vary from entire to undulate to broadly serrate with teeth angled toward the pointed leaf apex. Larger leaves, located along lower portions of branches, have lengths of about 5 inches (including 1-inch petioles) and widths of about 2½ inches. Leaves are slightly up-folded, especially nearer petiole. Veins are offset pinnate, with those of upper surface depressed and those of lower surface–a light yellow green–expressed. Leaf blades are densely and softly pubescent, the upper surface with longer hairs. Petioles, u-shaped in cross-section, are pubescent on the lower rounded portion, while the flat upper portion is mostly glabrous. Leaves become less pubescent with age.

Clammy groundcherry - Physalis heterophyllaPhoto 3: Leaves are mostly cordate with variable margins. Upper surface of leaves is shown except for two leaves on right.

Flowering may occur over several months, as new growth continues at tips of branches. Single flowers grow from the center of “groups-of-three” (see above) in upper portion of the plant. In bud, corollas are enclosed in a densely pubescent tear-drop-shaped calyx that is rounded at the pedicel and pointed at the tip. At bud stage, the calyx is closed by five narrowly triangular lobes that merge below to form the calyx tube. Buds, on a non-supportive pedicel, face downward. As flowers approach anthesis, the closed corolla pushes out of calyx and unfurls. The tubular corolla, to about ¾ inch wide and circular, comprises five flared, shallow lobes that narrow to a tube within the calyx (funnelform shape). The outer margin of corolla is sinuous with slight peaks at center of petals. Corollas are medium yellow with a prominent purple pattern radiating from the center toward the margins. Flowers have five stamens with stumpy, purple filaments from which large yellow anthers with reticulated ridges become exserted. As anthers disintegrate, ridges of anthers persist for a short time as filigree threads about the stigma. Larger plants may have two dozen flowers.

Clammy groundcherry - Physalis heterophyllaPhoto 4: Corollas are tubular, composed of five fused petals. Yellow anthers, with a reticulated surface, surround a green stigma. Corolla margin and deeply lobed calyx can be seen in inset.

After flowering, calyxes enlarge and inflate into papery, puffy, balloon-like husks with a bright green, globose developing fruit within. Husks are ten-ribbed “Chinese lanterns” tipped by the calyx lobes pressing together. At maturity, the dangling, inflated calyxes are about 1½ inches long and wide, on pedicels 1½ to 2 inches long. After fruits mature, husks become light brown and may become tissue-thin so that only the reticulated veins seem to remain.

Clammy groundcherry - Physalis heterophyllaPhoto 5: Calyxes enlarge and inflate into puffy husks that change from green to light brown and may become tissue-thin with fruit maturity.

The fruit of clammy groundcherry is a smooth, round, ¼-inch berry that becomes a dull yellow at maturity. Berries are filled with closely packed, flat, round seeds. Entire berries may be consumed by caterpillars without any seeds surviving.

Clammy groundcherry - Physalis heterophyllaPhoto 6: Fruit, including seeds, may be eaten by caterpillars of the straw moth (Chloridea subflexa).

For a partially to fully sunny garden with mesic to somewhat dry soil, clammy groundcherry would add nice textural variety. Husks are notable and decorative. Ripe fruit is edible. (The tomatillo of commerce is the fruiting structure of another species of PhysalisP. philadelphica.) Plants do not seem to be aggressive self-seeders. If a colony should become a problem, herbicide may be needed due to the root system.

Characteristics of clammy groundcherry that help separate it from the other other previously described groundcherry species in the state are: 1) cordate pubescent leaves, 2) clammy stems and leaves, and 3) indented circular base on inflated fruiting husks.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Heart-leaf Skullcap

Heart-leaf skullcap (Scutellaria ovata*) of the Mint (Lamiaceae) family is one of 11 skullcaps** found in Arkansas that have blue to purple, two-lipped tubular flowers. Heart-leaf skullcap occurs from Texas and Minnesota east to the Gulf and Atlantic Coasts, as far north as Pennsylvania. In Arkansas, it occurs throughout much of the state except lowlands of the Mississippi Alluvial Plain and West Gulf Coastal Plain. The genus name is from Latin for “small dish,” alluding to the depression of the fruiting calyx. The specific epithet is Latin for “oval” in reference to shape of the floral bracts. “Skullcap” refers to the shape of the upper portion of the calyx, which drops off with fruit maturity. Preferred habitat is open woodlands with dry to mesic, rocky soils as well in more sunny disturbed places such as rights-of-way and logged areas.

This species is a non-woody perennial. Plants have fibrous white roots along with more conspicuous long, shallow, white, thread-like runners (underground stems) that have widely spaced, opposite pairs of tiny white bracts. Runners may extend a foot or more from the parent plant. Runners, which may be branched, produce white rhizomes at their ends with rhizomes in alignment with the runners. Rhizomes, to an inch or more long and ¼ inch or more in diameter, have the appearance of a series of connected knobs. Old rhizomes decay after the new year’s plants mature.

Heartleaf Skullcap - Scutellaria ovataPhoto 1: New stems grow from rhizomes that formed the previous year. Photo mid-April.

Perennial plants grow from previous year’s rhizomes, with each rhizome producing one to several square stems, typically 1 to 2½ feet tall. Plants early in the growing season tend to be erect while those with flowers and fruit become ascending to leaning. Stems generally are not branched below the terminal inflorescence. Stems, along with the entire plant other than the flowers, are medium green. New plants, developing rhizomes their first year, are produced from seeds.

Heartleaf Skullcap - Scutellaria ovataPhoto 2: Plants grow from tips of rhizomes which decay as plants mature. New roots grow from base of new stems.

Leaves occur in pairs (opposite), with each pair rotated 90 degrees (decussate) from the next pair. Leaf shape conforms with the common name in that they are heart-shaped (cordate), although lowermost leaves may be oval and leaves within the inflorescence subtending racemes (spikes) may be spade-shaped (as in a deck of cards). Larger leaves, along middle of stems, may have a blade that is three inches long and two inches wide on 1½-inch, slender, four-sided petioles. Leaf size decreases toward the inflorescence and size decreases further within the inflorescence. The leaf blade may be indented at its junction with the petiole or the indention may be absent, with the blade extending a short distance onto the petiole. The leaf blade is generally flat, but blades without the basal indention tend to be “drawn down” at the petiole. Leaves are a medium green above and a lighter medium green below. Margins have prominent, narrow to broad, triangular, ascending teeth (dentate margins). Teeth extend from near the petiole to a single large pointed “tooth” at the leaf apex. Leaves do not have a minty scent when crushed.

The primary vein (midrib), secondary and lesser veins are notably depressed above and expressed below. Most secondary veins, joining midrib at an acute angle, are offset pinnate, however the lowermost pair of secondary veins are opposite. Overall, venation produces a reticulated pattern that causes leaves to appear rough (rugose).

With few exceptions, plants are covered by dense, short, colorless, soft pubescence. Upper and lower leaf surfaces feel soft, the upper surface softer due to longer hairs. Pubescence also extends uniformly across the upper and lower surface of four-sided petioles, while the petioles’ lateral surfaces are mostly glabrous. Pubescence on exterior of flowers, floral rachises, bracts and calyxes is glandular.

Flowering, in late spring, is characterized by long, narrow, terminal and lateral racemes along uppermost portions of stems. Axillary racemes typically occur as matched pairs subtended by opposite leaves. Racemes, 4 to 6+ inches long, consist of up to 40+ flowers on short pedicels arranged in closely spaced decussate pairs, along with a single terminal flower. Each flower is subtended by a small, dish-shaped, sessile bract. Flowers of a raceme reach anthesis sequentially from base to apex. All racemes of a plant tend to develop simultaneously.

Heartleaf Skullcap - Scutellaria ovataPhoto 3: Opposite pairs of decussate leaves grow from square stems. Opposite pairs of flowers are arranged in terminal and axillary racemes.

Lavender to purple corollas, to about 1 inch long, have a slender tubular lower portion that smoothly transitions to an expanded flared upper portion comprising a hooded upper lip and a broad, down-flared and ruffled lower lip. The face of the corolla is set at a right angle to the tubular lower portion. The tip of the upper lip has two small projecting lobes. The lower lip, larger than the upper, has an upper surface that is broadly rounded laterally and bowed up in its central ribbed portion. The lower lip has a white central zone with splotches of lavender or purple. It has an indented margin at its tip and toward the back in its side margin. As seen from the front, flowers have two orifices, namely, a small upper one formed by the upper lip and a larger lower one formed by both lips.

Heartleaf Skullcap - Scutellaria ovataPhoto 4: Opposite decussate pairs of flowers arch upward. Lower corolla lip has a central zone of white with blotches of lavender. Note glandular pubescence within the inflorescence. Photo late May.

Flowers have four stamens attached (adnate) to the lower portion of the corolla throat. The pistil comprises a deeply four-lobed ovary with a single style arising between the lobes. Lavender staminal filaments are tipped with two-lobed anthers that produce light yellow pollen. The style is white, with a small tapered stigma. Anthers and stigma are tightly positioned together just inside the small opening formed by the constricted upper lip.

Corollas emerge from short (1/8-inch-long), oddly shaped calyxes. These have a distinct saddle-like or helmet-like projection on the upper side of the tube. The lower side is more or less rounded. Calyxes, on 1/16-inch-long pedicels, are subtended by small, dish-shaped bracts of about the same length. Exterior calyx surfaces are mostly covered by short, dense, glandular pubescence.

Heartleaf Skullcap - Scutellaria ovataPhoto 5: Floral bract, corolla exterior and most of calyx are densely covered with glandular pubescence. Note lobes of upper and lower lips, including the two small lobes at tip of upper lip.

Ovaries have four round lobes (each with a single ovule), readily seen within the calyx after the corolla has fallen. With fertilization, lobes mature into 1/16-inch-wide, hard, rounded, one-seeded nutlets, each with two flattened sides and an “exterior” rounded surface. Nutlets are a dark purplish color, with tiny knobs covering the flattened sides. As nutlets mature, the calyx becomes light brown, its upper portion (the skullcap) drops off, and the nutlets fall from the saucer-like lower portion.

Heartleaf Skullcap - Scutellaria ovataPhoto 6: Display of a separated flower parts showing stamens, style, 4-lobed ovary, and calyx (side profile). Gaping calyx, as shown, closes after corolla is shed.

For gardening purposes, heart-leaf skullcap’s rugose and cordate leaves, fairly short stature and showy blue flowers are attractive in native woodland gardens and natural areas. Although the plant reproduces from rhizomes as well as seeds, excess plants can be easily removed in early spring to control numbers. This species does well in shady rocky sites. It is not a preferred deer food.

  • Characteristics of heart-leaf skullcap, such as degree and type of pubescence and size and shape of floral bracts, are variable across the species range. USDA recognizes nine subspecies.

** Characteristics of heart-leaf skullcap that distinguish it from the other 10 skullcaps in the state: 1) cordate planar leaves, 2) white runners that produce white rhizomes, 3) lower lip mostly white with lavender to purple splotches, and 4) oval floral bracts that are about same length as calyxes.

Article and photographs by ANPS member Sid Vogelpohl

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Know Your Natives – Sensitive Brier

Sensitive brier (or briar) (Mimosa quadrivalvis var. nuttallii*) of the Bean (Fabaceae) family is a sprawling perennial legume that is covered with prickles. The genus name is from a Greek word for “mime” or “mimic,” in reference to leaves in some species that fold when stimulated, suggestive of mimicking conscious life. The specific epithet is from Latin, meaning “with four valves,” in possible reference to seed shape. The varietal name honors Englishman Thomas Nuttall who, beginning early in the 19th century, published books on U.S. plants. This variety, sometimes treated at the species level as Mimosa nuttallii, occurs in the central U.S. from Texas and Louisiana to North Dakota and Wisconsin, with a couple scattered reports also from Michigan and Pennsylvania. It is found in sunny areas of prairies, roadsides and woodland margins where soils are sandy to rocky. In Arkansas, it occurs across much of the state except for lowlands within the Mississippi Alluvial Plain. Other common names include cat’s claw brier, bashful brier, and Nuttall’s sensitive brier.

Sensitive brier is a low-growing sprawling plant that develops a long, woody taproot an inch or more in diameter. New stems grow primarily from bases of previous year’s dead stems so that, over the years, short “caudex-branches” form, resulting in a splayed caudex, an inch or so below the surface. Taproots, an inch or more in diameter, have a garlic scent when freshly cut.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 1: New stems grow from base of previous year’s stems. Inset: splayed caudex and taproot.

A mature plant may have a dozen or more floppy stems that radiate from the caudex. Stems become tightly intertwined with other stems and surrounding vegetation. Stems, to 4+ feet long and unbranched, are terete with six slight longitudinal ribs. The plant hugs the ground in absence of other vegetation; stem ends may rise about a foot. Stems mostly disintegrate over winter, other than the lowermost portions which remain viable.

Sensitive brier is heavily armed with prickles (outgrowths of epidermis). The short, slender, recurved prickles are irregularly spaced along the ribs that extend along stems and onto petioles (leaf stalks), leaf midribs, petiolules (stalks of leaflets), and pedicels (flower stalks). Prickles hold the floppy stems in place against the ground or other vegetation. Prickles cause any plant part touched by a passerby (human or animal) to latch on. The entire plant is hairless (glabrous).

The 4- to 5-inch-long compound, alternate leaves are even-bipinnate, having four to eight opposite, even-pinnate lateral leaflets which are divided into 10 to 14 even-pinnate pinnules. Leaves, 4 to 5 inches long and spaced 1 to 3 inches apart, attach to stems between the ribs. A pair of weak linear stipules is located at the leaf base. The petiole is about one-third as long as the rachis (leaf axis that bears leaflets). Secondary leaflets or pinnules, about 3/16 inch long with tiny tips, have elliptical blades. Pinnules, medium green above and a lighter green below, have obscure venation except for midribs. Pinnule blades are more narrow on the up-rachis or distal side of midribs. Short pulvini (swollen sections subject to changes of turgor) at the bases of pinnules allow pinnules to fold along the leaflet midrib when touched, as well as overnight, on cloudy days and when plant is shaken.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 2: Left, upper leaflet surfaces obscured by folding of leaflets; lower leaflet surfaces shown on right. A stem segment (leaves removed) also shown. Note that the recurved prickles grow from ribs.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 3: Upper leaves subtend single, ball-shaped flower heads, as seen on this actively growing stem. Linear stipules can be seen at bases of petioles.

In mid-spring, new leaves along upper portions of stems subtend long, slender peduncles topped with ball-shaped flower heads. With anthesis, all 80 or so buds of a head open simultaneously. Each flower has 12 or more strongly exserted, straight, half-inch-long, thread-like stamens. With stamens radiating in all directions, the ball-shaped heads are about 1 inch in diameter. Individual flowers are not discernable. Rose to pink filaments are tipped, during the first day of bloom, with globular two-lobed anthers that produce light yellow pollen. Stamens encircle a small, elongate, green ovary topped by a style that has the same pink color and shape as filaments. Flowers each have a tiny calyx and five triangular petals that unite to form a one-eighth-inch long, bell-shaped corolla. Calyx is a light green, the corolla a light green to tan. After a single day of bloom, flower heads quickly fade as additional heads “open” up-stem. All non-flower parts of the plant are at first a light green that changes to medium green through the growing season.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 4: Flower heads reach anthesis sequentially from lower to upper stem. Note the ridged stems and numerous prickles.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 5: With peduncle removed, calyx and corolla of individual flowers can be seen. Inset: flower with 12 stamens. Note, below right, green ovary topped by a style with appearance similar to that of stamens.

In midsummer, sensitive brier produces slender pods with large prickles along ribs that extend the length of the pods. Each flower head produces a limited number of pods. Mature pods, to 3+ inches long, can be oddly shaped: seeds bulge such that pods are intermittently slim between them. As pods dry, they split into two valves. Seeds are smooth, dark brown, somewhat oval and with flattened sides, and about 1/8 inch long by 1/16 inch wide.

Sensitive Briar - Mimosa quadrivalvis var. nuttalliiPhoto 6: Flower heads produce prickly pods that enclose isolated seeds. Inset (¼ inch per square): shiny dark-brown seed are smooth with flattened faces.

Sensitive brier is suitable in a sunny, dry natural garden where the plant can grow without disturbance. Plants have attractive twice-compound leaves, showy flowers and an amazing display of prickles. They do not spread aggressively, either by seed or runners. They are difficult to grow from seed but can be started from cuttings. Seeds are a purgative.

Another Arkansas species with similar appearance is powderpuff or shameface (Mimosa strigillosa). Powderpuff, the only other Arkansas Mimosa, is found across the West Gulf Coastal Plain and southern portion of the Mississippi Alluvial Plain. It does not have prickles, and it spreads aggressively by runners. Another similar-looking plant is yellow puff (Neptunia lutea), but this species also does not have prickles and has yellow, more elongate flower heads.

  • Other scientific names that have been associated with sensitive brier: Mimosa nuttallii, Mimosa quadrivalvis var. angustata, Mimosa microphylla, Schrankia uncinata, Schrankia nuttallii, Schrankia angustata, Schrankia microphylla, Leptoglottis angustisiliqua, Leptoglottis chapmanii, Leptoglottis microphylla, Morongia angustata, Morongia microphylla, Morongia uncinata.

Note: Non-native invasive mimosa, a.k.a. silktree, (Albizia julibrissin) is not in the Mimosa genus.

Article and photographs by ANPS member Sid Vogelpohl

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