Saturday, May 1st, 1-2pm Benevolent Trees: Native Woody Plants in American Herbal Traditions with Steven Foster
Join Steven Foster on a photographic journey beyond mere plant identification to explore the remarkable human experience in interacting with woody plants for material and medicinal use, as well other ways of looking at our ligneous flora in both American history and contemporary experience.
Saturday, May 8th, 1-2pm Mosses: the Original Tree Huggers with Karen Willard
Mosses were one of the first plants to adapt to life on land, evolving from an ancient group of green algae around 450 million years ago. These plants are small and lack true vascular tissue, yet they have been able to colonize every ecosystem except for the ocean, living where most other plant groups can’t. In this program, Karen will explore some of the characteristics that make these plants unique, and will discuss their role in the biological community. The program will conclude with an overview of moss species common to Arkansas.
Wednesday, May 12th, 2-3pm Here Come the Invasivores! Foraging Invasive Species To Help Our Natives with Bo Brown
Join Bo Brown, author of Foraging the Ozarks, to learn about some of the tasty non-native and invasive plant species found in Arkansas. You’ll learn about methods of preparation, recipes, ethical collection, and ways to prevent the spread of these ecologically harmful species.
Thursday, May 13th, 1-2pm Who’s On Top: An Overview of theKnown Associations Between Plants and Fungi with Jay Justice
In this presentation, Jay will examine various types of mycorrhizal relationships, as well as other types of fungal-plant associations, including lichens, endophytic fungi, and myco-heterotrophic plants.
Saturday, May 15th, 2-3pm The Love Life of Ferns with Eric Sundell
The ferns are an ancient group of plants with a dominant presence in the fossils of the Coal Age, some 350 million years ago. And they remain, with their vascular tissues that transport water, minerals, and sugars, a prominent and competitive group in today’s modern flora. But unlike almost all of the modern plants we see around us, they have no seeds and no flowers. Instead, their life cycle is characterized by spores as well as by two quite different kinds of plants, one that produces those spores (and looks like a fern) and the other, the prothallus, a kind of alter-ego that looks like an alga or maybe a moss, that produces sperm that swim about on the forest floor hunting for eggs. We’ll take a look at the details of this bizarre and intriguing life cycle. We’ll also have a quick tour of Arkansas’ most common fernly beauties.
Saturday, May 22nd, 1-2pm Arkansas’s Grasslands: Natural History and Conservation with Theo Witsell
Synposis: Join Theo Witsell for a webinar on the grasslands of Arkansas, their natural history, and their conservation.
May 22nd, 3-4pm Ask the Experts! — Q&A Panel Discussion with Theo Witsell, Jennifer Ogle, and Eric Sundell
This is your chance to ask the experts questions you have about the native plants of Arkansas. Bring your questions to the live event, or submit them in advance to ANPS.President@gmail.com.
Lady Fern (Athyrium filix-femina*) of the Woodsiaceae (Lady Fern) family is a medium size fern of North America, Europe and Asia. The genus name originates from a Greek word referring to “door” in reference to the hinged indusia (protective spore covers). The specific epithet is based on Latin words for “fern” and “woman.” Lady Fern occurs across the U.S., including Alaska, as well as Canada. In Arkansas, Lady Fern is the only species of Athyrium and is found statewide. Preferred habitat is shady sites with moist to wet soils: rich woods, seeps, springs, moist areas of prairies, and at swamp and drainage borders. The common name relates to the graceful appearance of this “delicate” fern, as compared to “coarse” ferns, such as male fern (Dryopteris filix-mas).
Lady Fern is a hardy deciduous fern with shallow horizontal rhizomes to ¾ inch thick. Rhizomes produce new fronds (leaves) at their growing tips, with the bases of old fronds persisting for up to four years. Numerous wiry roots, with their lateral rootlets, grow from all sides of the rhizomes. Rhizomes of a mature plant occasionally divide, ramifying and rooting through the soil, to form a dense mat.
In early spring, tightly coiled fronds, pinnae (leaflets), and pinnules (secondary leaflets) emerge as “fiddleheads.” Protective papery elongate scales along the stipe (frond stalk), and the stipe itself, are reddish brown.
Ovate-elliptic fronds mature to 3 feet long and 10 inches wide; pinnae are narrower in shape and lanceolate-oblong. Fronds are light green above and below. Largest pinnae (5+ inches long and 1+ inches wide) are located near the middle of the rachis (pinna-bearing axis). Except for the two lowermost pinnae, which tend to be opposite, pinnae (20+ along both sides of rachis) are alternate. Size and separation of pinnae decrease distally, ultimately merging to form a fine-pointed apex. Fronds are mostly glabrous, except for the scales along the stipe, as noted above. The rachis is rounded on the lower side and flat with a central groove above. The stipe may be half as long as the rachis.
Lady Fern’s compound fronds are described as bipinnate to bipinnate-pinnatifid. The ultimate divisions, the pinnules, to ½ inch long and 3/16 inch wide, are sharply toothed with secondary veins terminating at the tips of the teeth.
Lady Fern has separate fertile and sterile fronds, with the same adaxial appearance. To find the fertile fronds, you turn them over to see the lower surface, which bears tiny clusters of spore-producing sporangia called sori (singular, sorus) or fruit-dots. Crescent- to oval-shaped sori are arranged in two rows on either side of the midrib of the larger pinnules. Early in development, the sori are partially covered by a translucent, hinged indusium. As spores develop, indusia dry and shift away to expose the sporangia and facilitate spore dispersal.
With dispersal of spores, the reproductive activity of the “sporophyte” phase of a fern’s life cycle concludes. In the soil, spores germinate to produce a prothallus, the “gametophyte” phase. The tiny prothallus produces gametes, sperm and egg. Sperm swim through ground moisture to fertilize eggs that have remained attached to the prothallus. Fertilization produces a zygote that, in turn, develops into a new sporophyte plant––the plant that we recognize as a “fern.”
For a shady to partially shady garden or natural area that has moist to wet soils, this delicate-cut fern should be considered. Plants have an airy appearance and provide nice contrast with coarse ferns and broad leaf plants. The weak fronds are easily damaged by wind and passing animals. Plants go dormant early with dry soil conditions. Lady Fern expands slowly by rhizome growth, but is not aggressive. For a similar appearing fern that is more compact, prefers drier soil, and tends to be evergreen, Marginal Wood Fern (Dryopteris marginalis), may be an alternative choice.
The ferns are an ancient group of plants with a dominant presence in the fossils of the Coal Age, some 350 million years ago. And they remain, with their vascular tissues that transport water, minerals, and sugars, a prominent and competitive group in today’s modern flora. But unlike almost all of the modern plants we see around us, they have no seeds and no flowers. Instead, their life cycle is characterized by spores and by two quite different kinds of plants, one that produces those spores and the other, the prothallus, that produces swimming sperm.
*Across its circumglobal range, Lady Fern has many variations. Two subspecies have been classified in the eastern U.S.: Southern Lady Fern (Athyrium filix-femina subsp. asplenioides) and Northern Lady Fern (Athyrium filix-femina subsp. angustum). These subspecies, which some authorities elevate to species, are distinguished by the location of the broadest widths of the fronds (closer to the base versus closer to the middle) and spore color, among other characters; however, variations do occur. The Arkansas subspecies is Southern Lady Fern, although the range of Northern Lady Fern approaches the state closely in Missouri and may occur within northern Arkansas.
Article and photographs by ANPS member Sid Vogelpohl
Canada rockcress (Borodinia canadensis*) of the Mustard (Brassicaceae/Cruciferae) family has small white flowers and long pendent bean-like fruits. The genus name most likely commemorates the Russian botanist Ivan Parfenievich Borodin (1847-1930) who founded the Russian Botanical Society. The specific epithet denotes the species’ occurrence in eastern Canada. In the U.S., it is found primarily from eastern Oklahoma and southern Minnesota, east to Massachusetts and the southern Appalachians. In Arkansas, Canada rockcress occurs primarily throughout the Interior Highlands. Habitat preference is dry to well drained, sandy to rocky soils of open areas. Other common names include sicklepod and sicklepod rockcress.
This biennial, developing from seed in late fall, forms an elongate taproot and a basal rosette of simple leaves over winter. The earliest basal leaves tend to be spatulate and petiolate while later basal leaves are mostly obovate and sessile. As the central stem develops, basal leaves may expand to 4 inches long and 1¼ inches wide. Early leaves are green to purplish above and dark purple beneath. Pinnate venation, though obscure, is somewhat enhanced by purplish coloration. Leaf margins have 6 to 8 prominent undulating pairs of teeth angled toward the apex as well as basal ear-like lobes on the lowermost blades. Basal leaves are covered with dense, white, straight or curved hairs.
A straight, erect, green to bluish central stem develops in spring as basal leaves drop away, growing to a height of 3 feet, including the terminal raceme. Robust stems may have a few lateral flower-bearing branches above. Stems have scattered straight or curved pubescence, more so near the base. Pubescence is lost as plants mature.
The alternate, simple, ascending to arching stem leaves are lanceolate to oblanceolate, sessile or short-petiolate near the base. Lower stem leaves are 4 inches long and 1 inch wide, the size decreasing upwards. Leaf pubescence is variable: lower leaves and lower leaf surfaces are hairier while more distal leaves and upper leaf surfaces may be glabrous. Venation of stem leaves is similar to that of basal leaves.
By mid-April, the growing stems are topped with a tight cluster of football-shaped flower buds covered with dense minute pubescence. As stems continue to elongate, the structure of the inflorescence becomes apparent: a bractless raceme, a hallmark of the mustard family. Primary racemes may bear 60+ flowers and grow to more than a foot long in fruit. On more robust plants, they may be branched. Flowers of a raceme bloom sequentially from base to apex. Pubescence is lost as fruiting progresses.
Flowers develop on down-curved, half-inch-long, minutely pubescent pedicels. Perianth parts are in fours: 4 sepals, 4 quarter-inch-long petals. The androecium comprises 6 stamens, 4 long and 2 short, another hallmark of the family. There is a single pistil. The narrow tips of the linear white petals (about 3/16 inch long) extend just beyond the sepals and become widely spread to expose the anthers. The elongate, 2-carpellate pistil, with its minute style, remains mostly hidden.
Fertilized flowers, the sepals shed, produce long, slender, glabrous, 2-valved, bean-like fruits (siliques) that become prominently curved with maturity. Mature siliques, to 4 inches long and ⅛ inch wide, are of uniform width and thickness. They become tangled with one another as they elongate. When fruits are mature, the valves break apart and seeds are shed. Dead plants with their prominent seedless fruits become a light tan in color.
Structure of the ovary and fruit of the mustard family is unique. The partition separating the valves is not a seed-bearing placenta––seeds are attached not to the partition itself (this would be axile placentation) but to the junction of the partition with the valve, creating parietal placentation. (The partition is often termed a false septum or replum.) There are thus 4 lines of ovules in the ovary and 4 lines of seeds in the mature siliques. This becomes evident when the siliques dehisce along the junction of the valves: valves fall away while the replum, with seeds still attached on both sides of its edges, remains on the receptacle. The flattened round to oval seeds separate one from another with each seed retaining a “halo” of the translucent replum. Seeds are dispersed by wind.
With its height and distinctive racemes, Canada rockcress adds textural variety to a garden (see Photo 6). Nectar and pollen are beneficial to small flies and bees. At the end of the growing season, plants quickly disintegrate. It is apparently not an aggressive self-seeder.
Three other species of the genus Borodinia occur in Arkansas: smooth rockcress (Borodinia laevigata), Missouri rockcress (Borodinia missouriensis), and Short’s rockcress (Borodinia dentata). Canada rockcress can be distinguished by its 1) pubescent basal leaves with prominent teeth (but not significantly lobed), 2) non-clasping, tapered to the base, mostly sessile stem leaves, and 3) down-curved pedicels bearing pendent flowers and wider long curved fruits.
*Formerly classified as Boechera canadensis and Arabis canadensis. More recently, based on DNA testing, Canada rockcress and other Boechera species in Arkansas have been transferred to form a clade with Borodinia macrophylla, an Asian species.
Article and photographs by ANPS member Sid Vogelpohl
Spring-beauty (Claytonia virginica), traditionally treated as a member of the Purslane (Portulacaceae) family but more recently as a member of the Miner’s-lettuce (Montiaceae) family, is a widespread, common, native wildflower, a perennial herb with lovely white, pink-veined flowers. The genus name honors John Clayton, one of Colonial America’s earliest botanists. The specific epithet refers to the state of Virginia, from where the specimen seen by Linnaeus, who described the species, was collected. In the U.S., spring beauty occurs from central Texas to Minnesota, east to New Hampshire and the Carolinas. In Arkansas, the species occurs statewide. Habitats are sunny to partly shady deciduous woodlands, prairies, and lawns. Other common names include Virginia spring-beauty, eastern spring-beauty, and fairy spud.
This low-growing, late winter to early spring ephemeral emerges from an ovoid to globose corm (a bulblike underground stem). Smaller corms are smooth and round; larger corms (to 2+ inches) tend to have bumpy irregular shapes. Smaller corms produce roots at their centers while larger corms have long ropy roots scattered across the entire lower surface. Similarly for vegetative growth, basal leaves and floral stems grow from centers of small corms but are concentrated at multiple “bumps” on the upper surface of large corms. New white ropy roots develop annually after vegetative growth is well advanced. Plants become dormant by mid-spring.
Seasonal growth begins in late fall with the appearance of glabrous, somewhat succulent, linear, basal leaves, to as long as 1 foot but only 1/16 inch wide. Leaves radiate from the corm along the ground. Distally, where the blades are exposed to sunlight, they are green (though sometimes reddish purple in winter when first emerging) and grass-like, tapering at both ends. Near the corm, where they are covered by living and decaying vegetation, the petioles are narrow and white. Except for the prominent midrib, leaf venation is obscure. Plants may spread to a diameter of several inches to 2 feet, the largest plants in full sun.
Flowering stems, also glabrous and rather succulent, emerge in early winter and bloom from March to April. Stems have two opposite, sessile, linear leaves (the cauline leaves) to 6 inches long and ¼ inch wide, similar to the grass-like portion of the basal leaves. Above the cauline leaf pair, stems extend directly into a raceme (sometimes more than one), with one or two small oval bracts at or immediately below the lowermost flower. Racemes comprise 8-20 flowers on long smooth pedicels alternating along the rachis; both pedicels and rachis may be reddish tinged. Flowers bloom sequentially from base to apex, with early, open flowers near the ground and uppermost flowers in a tight droopy cluster of small nodding buds. Plants may bear flowers in bloom for 1-2 months. As flowering stems continue to grow, they become semi-erect to 6+ inches long in fruit.
The sun-facing flowers, on slender pedicels, have 2 sepals, 5 petals, 5 stamens, and 1 pistil. The slightly overlapped sepals, positioned like a pair of hands, are a pale green with entire margins. The oval petals, also slightly overlapping, are broadest in the middle, with a rounded apex. Petals may be white to pinkish, with major veins variously highlighted in pink. Stamens and anthers also vary from white to pink. Filaments are broadened below, where they closely surround the pistil. During the first day of anthesis, stamens are erect as the light to dark pink pollen is shed; then, as anthers shrink, filaments recurve away from an erect central style. The style is topped by a slim stigma which, after pollen has been shed, divides to expose three stigmatic surfaces. The rain-drop-shaped, 1-chambered, superior ovary is mostly hidden by the lower, flatter portion of the filaments. Flowers, about 1/3 inch across, reclose at night and on cloudy days.
Fruits, 1-chambered, ovoid, peaked capsules, develop all along the fully extended racemes. Capsules split along 3 seams to release smooth shiny black seeds. The round slightly flattened seeds are from 1/16 to 1/8 inch across. Seeds have elaiosomes (fleshy external appendages) which facilitate dispersal by ants. Sepals remain persistent as seeds are dispersed and the plant goes dormant.
Spring beauty is a dependable and showy early spring flower. With its tendency to self-seed, it forms loose to dense colonies. In a garden, it may be welcomed or despised, depending on the gardener’s interests. Once established, removal of corms may be difficult, and spring beauty plants may be difficult to remove without damaging other desired plants. It provides a pleasing appearance in a woodland and can form a beautiful late winter/early spring floral blanket in a lawn. Flowers provide early spring nectar and pollen to various insects, and corms are eaten by small mammals. All parts of the plant are edible by humans, including the corms which may be cooked (basis for common name “fairy spud”) or used in salads.
Only one other native species of spring-beauty is known for certain in Arkansas, Arkansas spring-beauty (Claytonia arkansana), described as a new species in 2013 (www.phytoneuron.net/2013Phytoneuron/50PhytoN-Claytonia.pdf). It has rather spoon-shaped leaves, a bract subtending each flower, and is only know from crevices and ledges of sandstone bluffs in three central-Arkansas counties. Between 2006 and 2013, this plant had been called Ozark spring-beauty (Claytonia ozarkensis); however, there was a problem with the application of that name when it was described, necessitating the new name. Prior to that yet, these plants were lumped with what were later determined to be broad-leaved forms of Claytonia virginica, called forma robusta, and mis-identified as Carolina spring-beauty (Claytonia caroliniana), a more eastern species. Besides the two native perennial species of Claytonia in Arkansas, a presumed introduced population of miner’s-lettuce (Claytonia perfoliata), a western annual species, was discovered in a natural area in the state in 2019. This species looks very different from our native species, with rounded, often perfoliate cauline leaves.
Article and photographs by ANPS member Sid Vogelpohl
Yellow meadow-parsnip or smooth meadow-parsnip (Thaspium trifoliatum var. aureum) of the Carrot (Apiaceae) family has small yellow flowers with in-turned petals, much like those of the golden-Alexanders (Zizia aptera and Zizia aurea) (see last paragraph). The genus name, coined by Thomas Nuttall, is a play on Thapsia, a related genus of the Mediterranean region. The specific epithet is Latin for “three-leaved.” In the U.S., Thaspium trifoliatum occurs primarily from Pennsylvania and Illinois south to Alabama and Arkansas.* Within Arkansas, it occurs statewide, most commonly in the Interior Highlands and on Crowley’s Ridge. Habitat includes clayey to sandy or rocky soils of sunny, moist prairies and partially shaded woodlands.
This herbaceous perennial, with erect stems to 2½ feet, is supported by a main root that becomes elongate and horizontally positioned near the soil surface. This root, to 2 or more inches long, bears numerous spreading to descending smooth, ropy, white roots that may be 8+ inches long. The main root becomes rough, irregular and knobby as old stems decay and “buds” of additional ropy roots form. A mature plant may have a single stem or multiple stems with each stem developing from a separate growth-point on the upper side of the main root.
Stems are not branched except for a few axillary floral branches just below the terminal inflorescence (see below). The round, slightly ridged, hollow, thin-walled, stems as well as all other parts of the plant, are hairless (glabrous).
Plants bear both basal (radical) and cauline (stem) leaves. Radical leaves are both simple and ternately compound, with 3 leaflets. Stem leaves are typically trifoliate. Margins are finely serrate, more sharply so distally, and highlighted by a thin but distinct white line which tends to be broader at the serration tips. Leaves are a medium to dark green, firm to rather leathery. Venation is well-expressed adaxially (above) and slightly recessed abaxially (below). Tertiary veins terminate at serrations’ tips. Leaves have sheath-like, clasping bases (see Photo 3).
Simple leaves are ovate with a cordate base and rounded apex. Leaflets of compound leaves become narrower higher on the stem, with more attenuate bases. Simple leaves occur on stemless seedlings and as radical leaves on mature plants. They have a combination of palmate and pinnate venation––the broader leaves with palmate venation, the more elongate leaves with mixed proximate palmate veins and distal pinnate veins. Simple leaves are 1-4 inches long, somewhat narrower in width, and with petioles 1-4 inches long.
Compound leaves are typically trifoliate, with a terminal leaflet and an opposite pair of lateral leaflets. Lateral leaflets are broadly lanceolate, often with asymmetric bases, 1-2 inches long and about 1 inch wide. Terminal leaflets are similar, but with bases symmetric. Size of the compound leaves varies from plant base to apex; larger leaves may be 11 inches long, including a 1 inch petiole, and 4 inches wide. Occasionally, terminal leaflets are subtended by an “extra” pair of lateral leaflets so that the odd-pinnate leaves have five leaflets.
Considerable variation occurs in length of petioles (leaf stalks) and petiolules (leaflet stalks). Leaves and leaflets may be stalked, subsessile or sessile. Uppermost compound leaves associated with the inflorescence tend to be sessile.
The inflorescence, from March to May, consists of compound terminal and axillary umbels (to 3 inches wide) on erect, straight peduncles to 3 inches long. Umbels branch into 6-10 grooved rays to ½ inch long, each ray terminating in an umbellet of 6-12 tiny, pedicellate flowers. All umbellets of a particular umbel bloom at the same time with flowers opening sequentially from perimeter to center.
The pale yellow flowers, less than ⅛ inch wide, have a short calyx of 5 tooth-like sepals, 5 broadly oval petals, 5 stamens, and a 2-celled inferior ovary topped with a stylopodium bearing a pair of styles. Ovaries have 10 longitudinal wings, widest at mid-ovary. Petals are strongly incurved toward the flower’s center and do not unfurl with age.
In mid to late summer, a fertilized flower produces a 3/16-inch-long broadly elliptical fruit with prominent longitudinal wings. When mature, fruits are hard and dry, and split into two 1-seeded mericarps, each with a semi-persistent style. Fruits may persist on dry stems into fall. Dispersal would be mainly by wildlife, strong winds, gravity and surface water flow.
Yellow meadow-parsnip is an attractive perennial that provides basal wintertime greenery and attractive leafy stems in early spring. Due to its tendency to self-seed, this species may be best suited for a natural area or wild garden. In a more formal setting, removal of fruits before maturity may be appropriate. Similar-appearing golden-Alexanders reportedly are not as aggressive in self-seeding.
Other Thaspium taxa in Arkansas are hairy meadow-parsnip (Thaspium chapmanii), hairy-joint meadow-parsnip (Thaspium barbinode), and purple meadow-parsnip (Thaspium trifoliatum var. trifoliatum). Purple meadow-parsnip differs from yellow meadow-parsnip primarily by its dark maroon flowers.** Hairy and hairy-joint meadow-parsnips (T. chapmanii and T. barbinode, respectively) have thinner, more divided leaves that are more prominently coarsely and irregularly sharply toothed. Hairy meadow-parsnip has pale yellow to creamy white flowers and hairier and more dissected (2-3-ternate) leaves, while hairy-joint meadow-parsnip has golden yellow flowers and less dissected leaves (1-2-ternate).
Two Arkansas species of Zizia are easily confused with yellow meadow parsnip: golden-Alexanders (Zizia aurea) and the less common heart-leaf golden-Alexanders (Zizia aptera). Golden-Alexanders (Z. aurea) has several characteristics to aid in its identification: 1) flowers are a darker yellow and the central flower of the secondary umbellet is sessile as opposed to pedicellate, 2) fruits are ribbed or without ribs rather than strongly winged, 3) basal leaves are all compound rather than simple, and 4) habitat preference is for more moist soils. Heart-leaf golden-Alexanders (Z. aptera) is quite similar to golden-Alexanders, except at least some basal leaves are simple and cordate.
* On national distribution maps, the two varieties are often not separated.
**Thaspium trifoliatum has been classified into two varieties. T. trifoliatum var. trifoliatum with maroon flowers and T. trifoliatum var. aureum with yellow flowers. T. trifoliatum var. flavum and Thaspium flavum are synonymous with T. trifoliatum var. aureum.
Article and photographs by ANPS member Sid Vogelpohl
Bird’s-foot violet (Viola pedata) of the Violet (Violaceae) family, the paragon of the violets, has distinctive leaves and large, exquisite flowers in several colors. The genus name is the classical Latin name for violets. The specific epithet, the Latin for “foot-like,” refers to leaf shape. In the U.S., bird’s-foot violet occurs in two broad belts: 1) from southeast Texas and Louisiana north to the Great Lakes region and 2) from Mississippi to Kentucky east to the Atlantic coast and thence northeast into southern New England. In Arkansas, it occurs statewide except for the lowlands within the West Gulf Coastal Plain and the Mississippi Alluvial Plain. Habitat preference is sunny sites with well-drained, sandy to rocky, acid soils of upland woods, prairies and roadside slopes.
Plants have a vertically oriented, stubby, whitish rootstock with a few white ropy roots toward the base. The rootstock has a crown, positioned at or just above the soil surface, from which leaves and flowers emerge, but never stems. Plants are acaulescent––stemless. As leaves and flowers develop and fall off year by year, elongated horizontal petiole and flower stalk scars remain from fallen leaves and flowers. As the plant ages, the diameter of the crown increases so that the rootstock tends to become conical. Lacking rhizomes, clonal colonies do not form.
Bird’s-foot violet may have a dozen or more deeply, palmately dissected basal leaves. New palmate outer leaves with spatula-shaped lobes (“spatulate leaves” herein) develop in fall and persist through winter––plants are evergreen––while new inner leaves with linear lobes (“bird’s-foot leaves” herein) develop in mid- to late winter and persist through the growing season. As the new spatulate leaves develop, any remaining bird’s-foot leaves fade away. Along with the palmate leaves, small variously shaped leaves appear in fall in advance of the spatulate leaves.
The palmate leaves typically have 3 main lobes with an undivided central lobe and 2 lateral lobes divided into 3-5 lobes. Lobes of spatulate leaves are elongate with rounded apices that may be in turn slightly lobed to deeply incised. Lobe margins are stiff, entire and upturned, with pinnate venation. Short fine hairs may occur on the adaxial leaf surface (pubescence puberulent) and along margins (margins ciliate). The bird’s-foot leaves have a smooth margin with an occasional tooth. Blades of the spatulate leaves continue as narrow wings down the full-length of the petiole, whereas petioles of the bird’s-foot leaves are not winged. Spatulate leaves remain close to the ground from fall into spring; the later-arriving bird’s-foot leaves are at first ascending before reclining. As plants achieve bloom and beyond, the bird’s foot leaves mostly hide the spatulate leaves, which apparently decline through the summer. When in bloom, a plant may be 4 inches tall.
Leaves have slender weak petioles. The glaucous petioles, rounded below and grooved above, are typically a pale green but may be reddish. A weak pair of hidden lanceolate stipules, with ragged margins, occurs at the base of the petioles. Petioles of the bird’s-foot leaves continue to grow during and after flowering so that final leaf length may be 7+ inches. As these petioles recline, plant height remains to about 4 inches.
Flowers bloom primarily in March and April. The single flowers, arising directly from the rootstock crown, are borne on glaucous stalks, which bear an opposite pair of bracts. The slender, weak flower stalks continue to lengthen through the growing season. Early flowers are positioned at leaf-level, but later flowers are above the reclining bird’s-foot leaves. Unlike the weedy common blue violet, bird’s-foot violet does not produce cleistogamous flowers (producing seed without fertilization).
In bud, flowers are bent downward, but in bloom face forward or upward. Across their somewhat flattened face, they measure ¾ to 1+ inch. The calyx comprises 5 lanceolate, pale green, finely ciliate sepals about ½ inch long. Prominent auricles (ear-like lobes) extend down from their base.
The corolla comprises 5 petals: an upper pair of overlapping, back-flared petals, two lateral petals, and a larger central lip petal below. The upper pair are oval with a short base; the laterals are spurred at the base; and the lower petal twists backwards to form an elongate nectar spur with a rounded tip. Petals may be all blue to lavender (considered the “standard” color), bi-color with 3 blue to lavender lower petals and 2 upper purple petals, or rarely, all white. The lower central petal, when blue to lavender, is white at the base with prominent purple veins (nectar guides). (White flowers do not have highlighted veins.) Again unlike the common blue violet or the prairie violet, all the petals are beardless (without hairs).
Flowers have 5 stamens and a single, 3-carpellate pistil. The stubby stamens have pale yellowish green filaments tipped with flattened orange oval anthers. Stamens fit tightly around the pistil. The stubby glabrous pistil consists of a shiny pale green ovary and a post-like, whitish green, clavate (thickened at distal end) style. At anthesis, only the tip of the style is exposed beyond the anthers, with the tiny protruding stigma almost unnoticeable.
Ovaries of fertilized flowers develop into ellipsoid, glabrous capsules with 3 parietal placentas, each placenta indicating where 2 of the 3 carpels have merged. The 50 or so seeds become copper-colored when dry. For dispersal, exploding capsules can eject seeds a short distance, and, with a gel packet at the seed base, seeds can be dispersed by feeding ants.
In a garden, rock garden or natural area, bird’s-foot violet would be an ideal plant for a fairly sunny, well-drained, sandy to rocky site with minimal competition. With its distinctive foliage, large flowers with several color varieties, and lack of cleistogamous flowers, many gardeners consider bird’s-foot violet to be their favorite violet.
In addition to bird’s-foot violet, at least 14 other species in the genus occur in Arkansas. Of these species, prairie violet (aka crow’s-foot violet, Viola pedatifida) has similarly finely dissected, palmately lobed leaves. The two species are easy to distinguish at the time of bloom: flowers of prairie violet are smaller and the lateral and basal petals are bearded. Prairie violet is a species of conservation concern in Arkansas, at the southern edge of its range, having been documented in a few tallgrass prairie remnants in only a couple of northwestern counties.
Article and photographs by ANPS member Sid Vogelpohl
Two-wing silverbell (Halesia diptera) of the Storax (Styracaceae) family is one of several understory trees in the family with pendant showy white flowers. The genus name recognizes English botanist Stephen Hales who authored Vegetable Staticks* in 1727. The specific epithet is based on Greek words for “two-winged” in reference to fruit structure. In the U.S., two-wing silverbell occurs primarily from southeastern Texas, across Louisiana, southern Mississippi, most of Alabama, the Florida panhandle, and southern Georgia, with scattered occurrences in Arkansas and South Carolina. In Arkansas, it occurs naturally only in Nevada County. Habitat preference is sandy, wet to mesic soils of streambanks and shady bottomlands.
Two-wing silverbell, a deciduous species, occurs naturally either as a large shrub with multiple trunks or a medium-size, single-trunk tree. Trees may be broad and open in more shady sites or, in sunnier sites, more densely branched with a rounded outline. Branches are slender, with lower branches tending to be oriented horizontally, while upper branches are ascending and spreading. Shrubs and trees attain most of their length from terminal buds with lateral buds providing infill. Trees may reach a height of 15 to 30 feet with a similar width.
New branches are medium green with short dense pubescence. By the end of the growing season, new branches have lost their pubescence and are smooth and reddish brown. In subsequent growth years, bark develops grayish and reddish streaks. Over time, the streaks on lower branches and trunks evolve into ridges and furrows. Bark of mature trunks is moderately textured with blocky longitudinal flat ridges and narrow cluttered furrows.
The petiolate alternate leaves are broadly elliptic to obovate. A few small ovate leaves occur at the base of current year’s leafy branches and at the base of floral twigs (see below). While most leaves are medium green, the ovate leaves tend to be darker. The off-set pinnate yellowish green veins are recessed on the upper side and expressed on the lower side. Larger leaves may be 6¼ inches long, including a ¾ inch petiole, and 3¼ inches wide. Blade margins are irregularly serrate. Early in the growing season, upper leaf surfaces are short pubescent and puckered between main veins. With age, leaf pubescence is lost and the blade surface flattens. Leaves become yellowish in fall.
Floral twigs reach the bloom stage in late March into April at the same time that leafy branches are developing. Floral twigs grow from lateral axillary buds along one-year-old branches. A twig bears a cluster of 2-10 white bell-shaped flowers on long (ca ¾ inch) drooping pedicels emerging from a compressed raceme. While the lowermost one or two flowers of a twig may be subtended by an ovate leaf, more distal flowers are subtended by small bracts with additional tiny bracts occurring along the pedicels. Newly grown floral twigs are clothed with short dense pubescence that extends onto the sepals and petals.
When flower buds first appear, they are already pendant and white with an elongate football shape. A floral tube or hypanthium is fused to the ovary, so that the ovary is wholly inferior, rimmed with 4 indistinct triangular sepals. The snow-white, bell-shaped corolla comprises 4 petal-like lobes slightly united at their base.
At anthesis, the corolla of the ¾-inch-long flowers remains pendant, so that the 8 (twice as many as the corolla lobes) stamens and style remain somewhat hidden. Stamens are inserted on the base of the corolla, their white filaments united below and closely adjacent above, forming a column or tube. Elongate anthers face inward. Anthers split along their length to release pale yellow pollen within the stamen column. The slender style has a gentle taper from a relatively broad base to a flat stigma at its pointed apex. The style extends well beyond the anthers with that portion within the stamen column densely pubescent. Ovaries have up to four ovules. The persistent styles are retained as prominent beaks on the fruit.
Ovaries form large, oblong, dry, dangling and indehiscent fruits with an opposite pair of large longitudinal fin-like wings and a much-reduced pair of wings (more like ridges) set at 90⁰ to the larger wings. Fruits are to 1¾ inches long, including a ¼ inch spiked beak (the persistent style). Wings and ridges are widest at mid-fruit, tapering to both ends. Fruits are dark green and fleshy during development, becoming tan to brown in fall as the wings and surrounding soft tissue become corky. The corky tissue surrounds a hard woody stone with longitudinal ridges. The 1-4 white seeds within the stone are spindle shaped. Mature fruits, on dry pedicels 1-1½ inches long, may drop-off (abscise) in the fall or remain attached until spring. Fruits may be dispersed a short distance by wind or float away in flowing water. Floral twigs are entirely deciduous, dropping off after fruiting.
Two-wing silverbell is an excellent plant for a garden with mesic acidic soil. It is attractive as a multi-trunk shrub or single-trunk tree. It should do well in a woodland edge or a sunny urban setting with supplemental watering until well-established. Halesia diptera var. magniflora is available in the nursery trade and has larger and more numerous flowers. Flowering is better in sunny sites. Green fruits may be eaten by wildlife.
A second species of Halesia occurs in Arkansas, the common, mountain, or four-wing silverbell (Halesia tetraptera) of the Interior Highlands, which matures to 40 feet tall. It has sometimes been called Carolina silverbell (Halesia carolina) in Arkansas, although some authorities consider this more restricted in range farther to the southeast, from Mississippi to South Carolina and Florida, and differing in corolla size, degree of style and anther exsertion, fruit shape, and width of fruit wings. Two-wing silverbell can be distinguished from four-wing silverbell by 1) the pubescent abaxial surface of the corolla lobes and style rather than glabrous, 2) stamens 8± instead of 15±, 3) petals united only at the base as opposed to most of their lengths, and 4) fruit with 2 prominent wings instead of 4. The two species of the other genus of the Storax family in Arkansas, American snowbell (Styrax americanus) and big-leaf snowbell (Styrax grandifolius), are shrubs with slightly similar-looking leaves and bell-shaped white flowers. However, the snowbells have 5-lobed corollas, shorter petioles, and non-winged round fruits.
Ditch stonecrop (Penthorum sedoides) of the ditch stonecrop (Penthoraceae) family is a short-lived, herbaceous perennial of wetlands. The genus name originates from the Greek words for “five” and “marker” in reference to the pentamerous (five-part) floral structure. The specific epithet translates to “resembling sedum,” also in reference to floral structure.* In the U.S., ditch stonecrop is the only species of Penthorum; a second species is known from Eurasia. Ditch stonecrop occurs throughout the eastern U.S. to eastern Texas, Nebraska, and eastern North Dakota. In Arkansas, it occurs statewide. Habitat preference is full to partially sunny sites with shallow, standing to slow-flowing water, where mucky soils remain wet in low-rainfall conditions, such as ditches, floodplain depressions, pond margins, and marshes.
Young plants, growing during the summer months, have a single aerial stem above water as well as leafy basal branches that arise from submerged rhizomes. Basal branches, up to six inches long, remain parallel to the soil surface with ascending tips. White, string-like secondary roots descend from the main root and the basal branches. With plant maturity, these become dark and matted.
Erect stems, 1 to 2+ feet tall at maturity, are terete, slightly ridged, and slightly zigzagged between the nodes (this more prominent on new growth). They are light green to pale red (in more sunny sites). Floral branches arise near the stem apex, each subtended by a leaf. Stem pubescence is sparse, coarse below and becoming finer distally. Inflorescence branches are glandular pubescent. An aerial stem apparently dies soon after it has produced fruit.
Plants that do not have submerged bases do not develop basal branches. If an upper portion of a stem becomes submerged, it develops basal-branch look-alikes.
Stem leaves are alternate and lanceolate-elliptic, to 6-7 inches long and 1½ inches wide, the blade tapering to a pointed tip and base. Largest leaves occur mid-stem. Blades are glabrous and sessile to short-petiolate, with fine, mucronate (tipped) serrations along their margins. Alternate, tightly clustered leaves of basal branches are about 1 inch long and ½ inch wide. Lower leaves of the aerial stems drop-off as tips of the basal branches continue to grow.
The inflorescence develops over the summer months. It consists of 2-4 flower-bearing “arms,” 1-sided racemes (technically cymes), extending from the tip of the main stem and, often, 1-2 axillary floral branches immediately below. Flowering begins at the basal flower and extends distally as the racemes uncoil from their initial fiddlehead shape. The eventually straight, ascending and arching floral branches bear several to 15 flowers on minute (< ⅛ inch) pedicels. Floral branches may be up to 2 inches long and have few to 20+ flowers. Floral branches below the terminal racemes may be 1¾ inches long and may bear one to several lanceolate leaves that are to 1¼ inches long and ½ inch wide. Along with the dense glandular hairs on floral branches, noted above, tiny deeply serrated bracts occur. The inflorescence may become reddish with fruiting.
Flowers have a bowl-shaped hypanthium or floral cup, which is to 3/16 inch across and ⅛ inch deep, bearing 5 triangular green sepals. The greenish-white flowers, typically lacking petals, have 5 (sometimes 6) pistils (ovary, style and stigma) united below and 10 stamens. The pistils are arranged in a central ring with the stamens both alternate and opposite to them. Each pistil comprises a single carpel. Each ovary has central placentation, a prominent post-like style (with a wide conical base), and a large convex stigma. At anthesis, styles are erect but flare outward in fruit, as the shiny greenish white stigmas become black.
Fruits retain the form of the flowers with the hypanthium, sepals, and 5 projecting styles persistent. The ⅛ inch long styles give the 5-carpellate fruits a prickly appearance. As fruits develop, the entire floral structure may become reddish, ultimately turning tan to dark brown at maturity. Seed dispersal occurs when the style with its conical base drops off a chamber to allow numerous tiny oblong (1/32 inch long) white seeds to drop away.
For a garden or natural area, ditch stonecrop needs a site that is continuously wet to occasionally flooded, such as a water garden, drainage, or pond margin. Plants would provide cover for water-based insects and amphibians. Ditch stonecrop is a good native plant for aquariums because of its leafy basal branches, which grow naturally submerged.
* Sedums are in the Stonecrop (Crassulaceae) family, in which ditch stonecrop was once included. There are four species of sedums known from the wild in Arkansas: the native Nuttall’s stonecrop (Sedum nuttallii), widow’s cross (Sedum pulchellum), and woodland stonecrop (Sedum ternatum), and the non-native yellow stonecrop (Sedum sarmentosum). All have succulent leaves.
Article and photographs by ANPS member Sid Vogelpohl
Southern prairie aster (Eurybia hemispherica) of the Aster or Sunflower (Asteraceae) family is a slender stemmed plant with spectacular, inch-wide, lavender composite flowerheads. The genus name is based on Greek words for “wide” and “few,” a reference to big-leaf aster (Eurybia macrophylla), most likely to the ligules of the ray flowers. The specific epithet derives from the Greek words for “half” and “sphere,” in reference to the involucre. Occurrence in the U.S. is primarily from eastern Texas and southeastern Kansas, east to southwestern Kentucky and the panhandle of Florida, excluding lowlands of the Mississippi River alluvial plain. In Arkansas, the species occurs nearly statewide, excluding some Mississippi Alluvial Plain and northern Ozark counties. Preferred habitat is sandy to rocky, mesic to dry soils of upland prairies and open woodlands.
Southern prairie aster is a long-lived herbaceous plant that forms loose clonal clumps. Plants have a short vertically oriented main root with many descending roots and shallow runners. Runners, originating from various levels of the main root, extend to 6 inches from the main root. Unlike roots, runners are modified stems, and are thus segmented at nodes, with each node subtended by a small fully clasping bract. One to several deciduous stems grow from the apexes of the main root and runners. Older portions of the main root and runners become reddish brown, while roots are light tan.
The unbranched, mostly erect, wiry stems, to 20+ inches tall, are yellowish green to slightly reddish in sunlight. They are mostly glabrous, but may have short pubescence toward the inflorescence.
Basal leaves, present in spring and fall, and cauline leaves have different shapes. Basal leaves may be spatulate with an acuminate apex to broadly lanceolate. They are flexible and glabrous except for the smooth margins which are minutely roughened.
Cauline leaves are alternate, stiff and ascending, lanceolate to linear, with an acuminate to obtuse apex and a narrowing base. They decrease in size from stem base (to 8 inches long and ¼ inch wide) toward the inflorescence (1½ inches long and ⅛ inch wide or smaller). The closely spaced leaves are clasping on the lower portion of the stem (base extending half-way around stem) to sessile along the upper portion. Leaves are a dull medium green above and a shiny light green below. While the lower leaf surface is glabrous, the upper surface and margins are roughened by minute hirsute pubescence. The leathery (coriaceous) leaves are up-folded along the midrib, which is slightly depressed above and prominently expressed beneath. Pinnate secondary venation is obscure. At the time of flowering, lower leaves tend to drop off. Tufts of small leaves (or small flowerheads) occur in leaf axils below the inflorescence, more apparent distally, but do not develop unless the stem above such a node is damaged.
The inflorescence, with the bloom period extending from August into October, may be a single terminal flowerhead or a terminal flowerhead along with an additional 2-6 axillary flowerheads racemosely disposed immediately below. Flowerheads may also occur at the stem apex in a shortened corymb. Flowerheads are sessile or borne on peduncles to 3 inches long that may bear one to several scattered lanceolate leaf-like bracts. The hemispherical involucre is comprised of 50-60 phyllaries (bracts of the composite head) in 4 to 6 series. Involucres are to ½ inch long and 1 inch wide. The outer stout lanceolate phyllaries become elongate-triangular, smaller and thinner above. Phyllaries are spreading to ascending, with spiky mucronate tips, glabrous above and minutely hirsute beneath.
Flowering sequence of racemes proceeds downward from the terminal flowerhead. The composite flowerheads consist of 20-35 pistillate (no stamens) ray florets and ± 50 perfect (with pistils and stamens) disk florets, flowering sequentially from the perimeter to the center of the disk. As heads approach anthesis, ligules of the ray florets are erect and disk florets are covered by the flattened pappus (long hairs attached to the ovaries). As heads develop, the light to dark lavender strap-like ligules expand to ½ inch long and become widely spread around the disk. The ¼-inch-long yellow disk florets have tubular corollas with five short-triangular erect lobes. Stamens have slender filaments and elongate anthers which join laterally to form a ring around the style. As the style elongates through the anther ring, it picks up the pollen and carries it to the surface of the disk where it is exposed to pollinating insects. The long stigma then divides (bifurcates), with the paired stigmatic surfaces slightly separating.
With completion of flowering, the entire stem dries and the phyllaries loosen, with the eventual release of 1-seeded, strongly ribbed, indehiscent fruits (achenes). The ⅜-1 inch long, bullet-shaped, slightly flattened achenes are tipped with a ring of 20-30 rigid plumose hairs (pappus). The well-attached arched hairs provide lift for wind dispersal.
Southern prairie aster is a good selection for a native plant garden or natural area with mesic to dry soil. It is not aggressive but may form small colonies. With its narrow leaves and wiry stems, the plant will probably be unnoticed until it blooms. Flowerheads are large for an aster but occur in limited numbers.
An additional species of the genus which is known only historically from Arkansas (Benton County only) is big-leaf aster (Eurybia macrophylla), not observed in the state since 1926. Big-leaf aster has large heart-shaped leaves and flowerheads in open cymes. Southern prairie aster is easily distinguished from 22 other “asters” in the Symphyotrichum genus by the appearance of its leaves, stems and flowerheads.
Article and photographs by ANPS member Sid Vogelpohl
Tall thistle (Cirsium altissimum) of the Aster, Sunflower or Composite (Asteraceae) family is a tall biennial thistle with weak spines and pink to lavender flower heads. The genus name derives from a Greek root for “swollen vein” in reference to past use of the plants to reduce swelling. The specific epithet is Latin for “tallest.” In the U.S., occurrence is concentrated in an area extending from eastern Oklahoma and Arkansas northward into Minnesota to western Pennsylvania, along with scattered populations from eastern Texas into western South Carolina. In Arkansas, tall thistle occurs statewide. Preferred habitats include prairies, woodlands, wood borders, and disturbed sites, on mesic, well-drained, sandy, rocky, and loamy soils.
Plants in their first year have a rosette of long-petiolate ascending elliptical leaves with minute pubescence overall and margins lined with minute spines. First year plants have long (to 6+ inches) slender taproots with a swollen segment along the lower portion. New growth for the second year begins as a rosette of rugose, ground-hugging leaves with long pubescence and stout marginal spines. Mature second year plants have shallow, sinewy, radiating roots as well as remnants of the first year’s tap root.
A second year plant, growing to a height of 5 ft (shady sites) to 10 ft (sunny sites), has straight, erect, hollow stems, with a cross-section to ⅝+ inch. Mature stems become hardened and tough. Larger plants have a few relatively short (to 2 ft long) branches along their upper portion. Stems are densely covered with short dense hispid pubescence which extends onto branches as dense pilose pubescence. While pubescence of stems may be reddish, that of branches is clear. Slight longitudinal ridges extend down from the leaf petioles so that the lower stem becomes 8-sided in cross-section. With drying soils, plants are subject to the loss of lower leaves. Dried leaves hang down and persist. As the bloom period ends in late September, the entire plant quickly dies, though typically remaining erect into spring.
Stem leaves are alternate, green above and prominently white beneath. They become gradually smaller up-stem and toward the branch tips, with those at the base of flowerheads becoming bract-like. On mature plants, the largest leaves occur lower on the stem where they may be 1 foot long and 5 inches wide, often drooping with age. Larger leaves are sessile, the blades narrowing at the base. The upper leaf surface may be glabrate (hairless) or densely short hispid; the lower surface is white with a dense mat of minutely short appressed wooly hairs. Leaves are generally lanceolate (larger leaves) or elliptic (smaller leaves) in overall outline, varying from uncut to deeply pinnately lobed from plant-to-plant and even on the same plant. Leaves on sunny-sites tend to be lobed whereas plants in the shade tend to bear uncut leaves. Lobed leaves have about 5 alternate pairs of narrowly triangular lobes (incision does not extend to midrib) and a similar apical lobe. Lobe margins are mostly smooth (entire) with a large terminal spine and a few smaller lateral spines; margins of unlobed leaves are mostly serrate with small spines at the tips of the teeth. In general, the leaf outline is consistent for an entire plant, but upper leaves of a lobed plant may become gradually unlobed. Venation, recessed above and expressed below, is pinnate, with secondary veins of deeply lobed leaves terminating as spines at the lobe tips.
The inflorescence, in August to September, consists of single composite flowerheads growing on peduncles from the uppermost leaf axils. Involucres of the flowerheads are ball-shaped in bud and become vase-shaped in bloom. They comprise tightly imbricated, lanceolate phyllaries (bracts), spirally arranged in about ten series. Phyllaries are medium green along their upper exposed half, typically with a central whitish stripe. They terminate in slender straight piercing spines. Spines lower on the involucre project outward or downward while upper spines tend to be ascending and may be up-hooked at their tips. There may be a dark spot at the base of the spine. Phyllaries are broader at the base of the involucre and become lanceolate to linear at the rim, with the linear phyllaries to ⅝ inch long.
Flowerheads are composed of 100+ perfect disk florets, each with five stamens and a pistil. Florets are densely packed within the confining involucre so that marginal florets “mushroom” over the edge, broadening the flowerheads to 2 inches across. Florets, in pink to lavender shades (rarely white), have slender tubular corollas with 5 linear lobes, 1 positioned below the style and 4 above. Corolla tubes attach to the tops of the stubby-elongate inferior ovaries, each encircled by a pappus of inch-long, white bristles. As florets approach anthesis (blooming centripetally from involucral margin inward), corollas elongate beyond the pappus. The 5 stamens, with fuzzy white filaments, are tipped with elongate anthers fused into a ring. The anther ring is exserted beyond the corolla tube. As the style exserts through the anther ring, it picks up and carries the white pollen well beyond the anthers, making it available to foraging pollinators. As the anthers fade and the pollen is dispersed, the darker colored, minutely bilobed stigma at the tip of the style is fully exserted. Individual florets are about 1 inch long with a ¾ inch slender tube (hidden within the involucre) and ¼ inch lobes.
As early flowerheads pass anthesis, the heads fade while others are still in bloom. With completion of flowering in late September, the entire plant dies. As the fruits (achenes) within an involucre mature, a mass of achenes and pappus expands. Some clumps, especially in wet weather, drop near the parent plant while some individual achenes becoming airborne. The light brown, slightly ribbed, bullet-shaped achenes (flat top and pointed base) are <¼ inch long with apical collars that allows the inch-long pappus to easily separate.
For a garden or natural area, tall thistle’s droopy lower leaves tend to die so that plants may become unattractive. However, when the showy flowerheads appear, it reasserts itself as a striking plant. Nectar is favored by butterflies and the achenes are a valuable food source for finches and other small birds and small mammals. Tall thistle is somewhat shade tolerant. Plants may self-seed too well, but young plants can be removed while in the rosette stage. It is not eaten by deer.
Tall thistle is one of nine species (two non-native) in the Cirsium genus in Arkansas, all having pink to lavender flowerheads. Of the other eight species, the ones (all native) with the most similar leaf outline are Carolina thistle (Cirsium carolinianum), field thistle (Cirsium discolor), swamp thistle (Cirsium muticum), Englemann’s thistle (Cirsium engelmannii), and Nuttall’s thistle (Cirsium nuttallii). Tall thistle has generally less lobed leaves, or when lobed, more broadly so, than the other species. It also has leafier upper stems and peduncles. Like many large Composite genera, though, the species distinctions are not always clearly marked.
In addition to the nine Cirsium species, six additional “thistles” in the Composite family occur in Arkansas, namely, three in the genus Carduus (lavender to purple flowers on heavily spined stalks), one in Centaurea (yellow flowers), and two in Sonchus (“sow-thistles”; yellow flowers).
Article and photographs by ANPS member Sid Vogelpohl