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  Asclepiadaceae: Asclepias speciosa

  R. Neil Reese

  Asclepias speciosa is a perennial herb with milky white sap, growing from a deep rhizome with solitary stems that are simple or occasionally branched, growing 50 to 100 cm in height and densely covered in hairs toward the top. The simple leaves are usually opposite with a short petiole 2-13 mm in length. The blades are entire, broadly lanceolate to ovate. 8-20 cm long and 2.5-10 cm wide, with a thick covering of hairs on the underside. The inflorescences are few to several in the upper leaf axils, each coming from a 2-10 cm peduncle 1-3 cm long hat are having 10 to 40 flowers attached by a 1-3 cm long pedicel that is covered with short hairs. The flowers are 15-28 mm long, the calyx is green to purple, covered with hairs and with 5 lobes that are 5-7 mm long. The purple to rose colored corolla lobes are rounded, reflexed and 9-15 mm long the apex is attenuated looking like a crown. The fused stamens and pistil os pale rose to pinkish-cream colored, broadly obconic 1-1.5 mm tall a\nd 2.5-3.3 mm wide. The fruit are erect follicles that are 7-11 cm long and 2-3 cm wide. The sees are ovate 6-9 mm long with long white to brownish hairs. Showy milkweed blooms from May through August on the banks of lakes, ponds and streams or moist areas on prairies throughout much of South Dakota. Showy milkweed and common milkweed are very similar. They can be distinguished by their flower petals, with A. speciosa having longer narrower petal lobes that give the flower the appearance of a crown.

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  Asclepiadaceae: Asclepias syriaca

  R. Neil Reese

  Asclepias syriaca is a perennial herb with milky white sap, growing from a deep rhizome with solitary stems that are simple or occasionally branched, growing 0.6 to 2 m in height and densely covered in hairs toward the top. The simple leaves are usually opposite with a short petiole 2-13 mm in length. The blades are broadly lanceolate to ovate. 6-30 cm long and 5-11 cm wide, margins entire, with a thick covering of hairs on the underside. The inflorescences are few to several in the upper leaf axils, each coming from a 1-14 cm peduncle 1.5-4.5 cm long that have 20 to130 flowers attached by 1-3 cm long pedicels that are covered with short hairs. The flowers are 11-17 mm long, the calyx is green to purple, covered with hairs and with 5 lobes that are 2.4-4 mm long. The purple to rose to rarely white colored corolla lobes are rounded, reflexed and 9-15 mm long the apex is attenuated looking like a crown. The fused stamens and pistil os pale rose to pinkish-cream colored, broadly obconic 1-1.9 mm tall and 1.5-2.5 mm wide. The fruit are erect follicles that are 7-11 cm long and 2-3.5 cm wide. The seeds are ovate 6-8 mm long with long white to brownish hairs. Common milkweed blooms from May through August on the banks of lakes, ponds and streams or moist areas on prairies and along roadsides throughout much of South Dakota. Showy milkweed and common milkweed are very similar. They can be distinguished by their flower petals, with A. speciosa having longer narrower petal lobes that give the flower the appearance of a crown.

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  Asclepiadaceae : Asclepias tuberosa

  R. Neil Reese

  Asclepias tuberosa is a perennial herb with milky white sap, growing from a deep rootstock with 1 to many stems arising from thick crown. The stems are simple to having a few branches toward the top, generally covered with short hairs, and reaching 30 to 90 cm in height. The ascending to spreading simple leaves are alternate on the lower stem but become subopposite to opposite where the flowers emerge. The blades are entire, linear to broadly lanceolate, 5-10 cm long and 7-23 mm wide with margins that curl downward. There are 1 to several umbellate clusters of flowers at the ends of the stem and branches and in the upper leaf axils. Six to 25 flowers are attached to a short peduncle (< 3 cm long) or sessile with each flower having a short (12-19mm) pedicel. Flowers are 11-16 mm long, the calyx is covered with hairs and green to purplish colored, with lobes 2-4 mm long. The bright orange to reddish corolla lobes are reflexed and 5.5-8.5 mm long. The fused stamens and pistil is about 1-1.5 mm tall and wide. The fruit are tapered at both ends, 8-15 cm long and 1-1.5 cm wide. The seeds are oval 5-7 mm long with long white hairs. Butterfly milkweed blooms from May to August in sandy prairies and open woodlands in a few counties in both eastern and western South Dakota.

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  Asclepiadaceae : Asclepias verticillata

  R. Neil Reese

  Asclepias verticillata is a perennial herb containing milky white sap, with 1 to a few stems arising from a fibrous crown, occasionally branched and 35-90 cm tall. The sessile leaves are whorled with 3-6 leaves per node. The blades are entire, linear, 1.5 to 8 cm long and about 1 mm wide. The inflorescences are few to many in the axils of the upper leaves, each containing 6-20 flowers. Flower buds appear yellowish but produce white to greenish white flowers. Each flower is attached to a short peduncle (1-4 cm long) by a 5-11 mm pedicel. Calyx lobes are green to purple tinged 1-2.5 mm long and the corolla lobes are white to greenish white, reflexed and3.5-4.5 mm long. The fruit are erect follicles 8-10.5 cm long and < 1 cm wide. The ovate seeds are 5-6 mm long with long white hairs. Whorled milkweed blooms from June through September in the prairies, flood plains and open woods of South Dakota.

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  Asclepiadaceae: Asclepias viridiflora

  R Neil Reese

  Asclepias viridiflora is a perennial herb, with milky white sap, having 1 or 2 stems growing from a taproot, with the stems only occasionally branched, stout and 10 to 60 cm tall. The simple leaves are opposite, or nearly so, to alternate. The blades are entire, variable in shape from linear to almost round, ascending to widely spreading, 4-14 cm long and 1-6 cm wide and having a few to a dense covering of whitish short woolly hairs. There are 1 to many inflorescences scattered in the axils of the leaves of the upper half of the stem. Each umbellate cluster contains 20-80 flowers, each with a short (5-15 mm) pedicel attached to a 2-20 mm peduncle. The flowers are 9.5-12.5 mm long with a green to purple tinged calyx with lobes 2-3 mm long. The corolla is pale green, with reflexed lobes 5.7-7 mm long. The fused stamens and pistil is also pale green and 1.2-1.5 mm tall and 1.2 -1.4 mm wide. The fruit is a follicle, swollen in the middle and tapered at both ends, 7-15 cm long and about 2 cm in the widest section. The seeds are obovate, 6-7.5 mm long with long tan hairs attached. Flowering occurs from June through August. Green milkweed grows on sandy to rocky soils in prairies throughout much of South Dakota.

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  Asteraceae: Achillea millefolium

  R. Neil Reese

  Achillea millefolium is a rhizomatous perennial herb which grows 30 cm to 100 cm in height. The leaves are alternate, compound bipinnately dissected, 5-20 cm long and feathery in appearance. Flowers are arranged in heads that are usually collected into flat-topped clusters. Heads are surrounded by imbricate bracts in several series and contain 10 or less ray flowers and 10-25 disk florets. Petals are white to cream-colored or rarely pinkish and bloom from May to June (later in higher locations). Fruit are flattened achenes that lack a pappus. This species is commonly found on all northern continents in mildly disturbed areas, meadows, woods, and prairies. It is common throughout South Dakota

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  Asteraceae : Ageratina altissima

  R. Neil Reese

  Ageratina altissima is a perennial herb arising from a rhizome, with upright or sometimes ascending stems, covered with short spreading hair, growing from 30 to 150 cm tall. The simple, opposite petiolate leaves have blades that are ovate to broadly ovate, contracted at the base and pointed at the tip, 6-15 cm long and 3-12 cm wide toward the base and smaller toward the top, with variously toothed margins. Each pair of leaves is positioned at a 90-degree angle from the pair above and below. The inflorescence is made up of flat-topped clusters of heads. Each head has a 3-5 mm involucre of bracts that are all about the same length. There are 12-24 white disk flowers that produce 5-sided achenes that have a bristly pappus and, when mature, appear as fluffy white balls like dandelions and seeds are carried in the wind. White snakeroot blooms in August through October in open woods and disturbed sites in eastern and south-central parts of South Dakota.

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  Asteraceae : Ageratina altissima

  R. Neil Reese

  Ageratina altissima is a perennial herb, arising from a fibrous. creeping rootstock, growing from 0.4 m to 1.5 m in height. The stems are variously purple spotted to uniformly purple. The leaves are simple, in whorls of 3-6, short-petioled, the blades lanceolate to ovate-lanceolate, serrate. The inflorescence is a flattened cyme, and the flowers are in heads. The involucral bracts are imbricate obtuse and purplish. Flowers are white, light pink to purple and bloom from July to September. Fruits are achenes. White snakeroot is found in wet meadows, stream and pond margins, springs, and boggy places. This species is commonly found at low to mid elevations in the Black Hills.

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  Asteraceae : Agoseris glauca

  R Neil Reese

  Agoseris glauca is a perennial herb having a large taproot and can grow from 8–50 cm tall. It has linear to oblanceolate leaves, 3–35 cm long, the margins are entire or with 1 to 3 pairs of shallow lobes. Stems and leaves are glabrous to sparsely villous. Flowers appear in a terminal head on a long scape with an involucre that is 1–2 cm long; phyllaries linear-lanceolate to lanceolate, in 2 to 3 indistinct series, green, glabrous to villous, sometimes glandular, often darkened along the midvein. Heads contain 15 to 150 flowers that are all ligulate, yellow, the ligules 6–22 mm long and each floret having a pappus 8–18 mm long. The fruit is an achene, with a body that is 4–9 mm long with a beak ranging from 0.5–3 mm long.

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  Asteraceae : Ambrosia trifida

  R Neil Reese

  Ambrosia trifida is an annual herb growing up to 2 m tall, but may reach over 6 m in rich, moist soils. The stem has a woody base and are branched or unbranched. Leaves are mostly oppositely arranged, with blades that are variable in shape, usually palmately lobed, and often with toothed edges. The largest leaves can be over 25 cm long and 20 cm wide, with petioles several centimeters long. They are glandular and rough in texture. The flowers are arranged in a spike, monoecious, with plants bearing inflorescences containing both pistillate and staminate flowers. Staminate flowers are yellow to greenish with no petals, about 3mm across, hanging down on short stalks along the spike. Pistillate flowers are indistinct, hidden in clusters of short leafy bracts. The fruit is a bur a few millimeters long tipped with several tiny spines.

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  Asteraceae : Anaphalis margaritacea

  R. Neil Reese

  Anaphalis margaritacea is a rhizomatous dioecious perennial herb that often grows in large patches. The stems are simple, covered with white wooly hairs, and grow from 20 to 60 cm tall. The alternate leaves are linear to linear-lanceolate, 4-9 cm long and sessile and often clasping at the base. The tops of the leaves are green, and the lower side covered with white hairs. The lower-most leaves usually withered or lacking at the time of flowering. The heads appear in July and August in flat-topped to rounded clusters. The heads have several series of imbricate involucral bracts that appear pearly-white, the involucre 5-8 mm tall and woolly at the base. The heads of male plants have numerous yellow, tubular, staminate flowers. The female plants with numerous yellow, pistillate tubular, flowers with a few functional staminate flowers. The fruits are achene-like and mature in the fall.

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  Asteraceae : Antennaria neglecta

  R. Neil Reese

  Antennaria neglecta is a perennial stoloniferous herb that forms mats of dioecious colonies. The basal and stolon leaves are 1-nerved, green above with white hairs covering the lower side, 1-3 cm long and less than 1.5 cm wide. The erect flowering male or female plants have stems that are 6-25 cm tall and covered with white hairs, having thin leaves tipped by a flat, often curled appendage. The heads are usually clustered in dense capitate to open cymes and have narrow involucral bracts, 5-7 mm long, the outer bracts are brown below and scarious white above. The pappus is longer than the stigmas in female plants. The achenes are slightly tapered at the ends and 1.2-1,5 mm long. Field pussytoes blooms from March through June in pastures, prairies and open woodlands throughout South Dakota.

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  Asteraceae : Arnica cordifolia

  R Neil Reese

  Arnica cordifolia is a perennial herb arising from long, creeping rhizomes, growing to 60 cm tall. It has two to four sets of opposite leaves on the flowering stem, each having a long petiole. Basal leaves are cordate, with long petioles and dentate margins. The cauline leaves are heart-shaped to arrowhead-shaped, with finely dentate margins. Leaf blades are 4-12 cm long and 2-9 cm wide. The inflorescence is composed of a single or occasionally 2-3 turbinate to campanulate heads, each 5–9 cm wide. The involucral bracts are 1-2 cm long, covered with white-hairs and sometimes studded with resin glands. Each head has 10-15 ray flowers with ligules 15-30 mm long and the center of each head contains several golden yellow disc florets. The achenes are 6-9 mm long with short hairs and/or glands. The pappus has long white barbed hairs. The flowers usually bloom from May through August. Heartleaf arnica grows in western South Dakota.

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  Asteraceae : Artemisia absinthium

  R Neil Reese

  Artemisia absinthium is a perennial herb to weak shrub, very fragrant, growing 40-120 cm tall, with the stems greenish with grooves and covered in short white hairs. The silvery leaves have long petioles and are spirally arranged, greenish gray above, white below, covered with silvery-white hairs, and minute oil-producing glands. The basal leaves are up to 25 cm long, bi- to tripinnate and the cauline leaves are smaller, 5–10 cm long, less divided, and with shorter petioles. The uppermost leaves may be much reduced becoming simple and sessile. The inflorescence is a diffuse panicle of heads with each head having involucral bracts 2-3 mm long and the receptacle is covered with numerous long hairs interspersed with the florets. The outer disk flowers are female and the inner florets are perfect. The achenes are cylindrical. Wormwood is an introduced species from Eurasia but is naturalized throughout the northern half of North America. It is found in open fields and along roadsides in many locations in South Dakota.

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  Asteraceae : Artemisia cana

  R Neil Reese

  Artemisia cana is perennial aromatic shrub mostly growing to < 1 m tall, but occasionally taller. The older stems become twisted with exfoliating bark and the younger stems are greenish, covered with grayish hairs. The lanceolate leaves are narrow, ranging from 2-9 cm in length, not often more than 5 mm wide, have a silvery gray pubescence and are retained year-round. The inflorescence is a series of spike-like, leafy panicles of small heads. The involucre is 4-5 mm long and has a naked receptacle. The several tiny disk flowers are all perfect producing small dark achenes. Silver sagebrush bloom in August and September and can be found in both east and west river South Dakota.

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  Asteraceae : Artemisia dracunculus

  R Neil Reese

  Artemisia dracunculus is a woody, perennial shrub, often quite fragrant, with stems ranging from 40 to 150 cm tall. The stems arise from thick, horizontal rhizomes growing singly or in clusters. The stems are often reddish colored and smooth to pubescent. Leaves are alternate, linear, 2 to 8 cm long and 1 to 6 mm wide. Basal leaves are cleft with 1 to 3 lobes. The inflorescence is a panicle with numerous heads. Each head is surrounded by an involucre that is 2-3 mm tall and has a naked receptacle. The yellow outer florets are pistillate and fertile. The central flowers are yellow, sterile, with ovaries that are abortive. The fruits are achenes elliptical and about 1.5 mm in length. Wild tarragon blooms in August and September and is usually found on dry open slopes throughout South Dakota.

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  Asteraceae : Artemisia frigida

  R Neil Reese

  Artemisia frigida is a low, spreading sub-shrub arising from a woody crown, growing from 10 to 40 cm tall. The plant has a fragrant scent, and the stems and leaves appear whitish to gray because of the dense covering of appressed hairs. Numerous leaves are clustered toward the base and scattered along the stems. The lower leaves are petiolate with blades that are up to 12 mm long, often divided several times with the segments about 1 mm wide. The upper leaves become sessile and reduced in size. The inflorescence varies from an open panicle to a raceme of small heads, each with an involucre of bracts 2-3 mm tall. The receptacle has many long hairs between the numerous small yellow flowers. The outer florets are pistilate and the central ones are perfect. Both produce small achenes. Prairie Sagewort blooms from early summer until very late in the fall. This species is common on open plains, throughout much of South Dakota.

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  Asteraceae : Artemisia ludoviciana

  R Neil Reese

  Artemisia ludoviciana is an aromatic, rhizomatous perennial herb that grows from 30-100 cm tall, covered in white hairs. The alternate, linear to lanceolate leaves are 3-11 cm long and up to 1.5 cm wide and are also covered in woolly gray or white hairs. The margins of the leaves are entire to irregularly lobed. The inflorescences are terminal narrow panicles of many nodding flower heads. Each small head is about 0.5 cm wide, surrounded by hairy involucral bracts 2.5-4 mm long. The receptacle is naked with numerous small yellow florets, the outer ones pistilate and the central florets are perfect. The fruit is a minute achene. Flowers bloom from July to October in most counties in South Dakota.

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  Asteraceae : Artemisia tridentata

  R. Neil Reese

  Artemisia tridentata is an erect, branching, aromatic, evergreen shrub, having both a deep taproot and a broad shallow root system, and growing from 0.5 to 3 m in height. The older stems are dark colored and are often gnarled with exfoliating bark. The younger branches are covered with a short pubescence. The leaves are wedge shaped, narrow at the base and tridentate at the tip. The inflorescence is a loose panicle of near sessile heads. The heads have involucral bracts 2-4 mm long and covered in whitish hairs. The several yellow florets are attached to a naked receptacle and are all perfect. The leaves contain camphor and other essential oils. The achenes are small and very dark when mature. Flowering occurs from June into September. Big sage is found on open dry plains and hills in western South Dakota.

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  Asteraceae: Balsamorhiza sagittata

  R Neil Reese

  Balsamorhiza sagittata is a perennial herb growing from a deep taproot with stems arising from a branching crown and reaching 80 cm in height. The foliage is covered with silvery hairs, often making the plant appear and feel velvety. The silvery-gray simple basal leaves are petiolate, arrowhead shaped, with blades 20-40 cm long and the margins are entire. The cauline leaves are linear to narrowly oval in shape, smaller and coated in fine to rough hairs, especially on the undersides. The inflorescence consists of one or more heads, usually solitary on each stem. Each head is surrounded by an involucre of 2-4 series of bracts and the receptacle is broadly convex. There are 13-25 yellow ray flowers with ligules 2-4 cm long surrounding a center with many yellow disk flowers. The fruit is a roughly four-sided achene, 7-8 mm long lacking a pappus. Arrowhead balsamroot blooms from May to July on open hillsides and in valleys of western South Dakota.

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  Asteraceae : Cirsium drummondii

  R. Neil Reese

  Cirsium drummondii is a biennial or perennial herb growing to 110 cm tall and blooming only once before dying. The plants are stout-stemmed and unbranched. The alternate leaves are oblanceolate, 8-25 cm long and 1.5-6.5 cm wide., with a spinose margin. The lower leaves are larger and more numerous toward the base, ascending and the upper leaves are deeply divided with the segments triangular in shape. The inflorescence is a terminal head (occasionally 2-3), about 7 cm in diameter with an involucre of 4-7 rows of bracts, 2-3.5 cm long, the outer 2 rows purplish and spine tipped. Ray flowers are lacking, with disk flowers rose purple in color and 38-44 mm long and the style is exerted. The achenes are straw colored with purplish streaks and a yellowish rim 4-5.5 mm long and < 2 mm wide with a bristly pappus 30-40 mm long. Drummond’s thistle blooms from June to early August in moist meadows, pine woodlands and along roadsides only in the Black Hills of Wyoming and South Dakota.

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  Asteraceae: Cirsium flodmanii

  R Neil Reese

  Cirsium flodmanii is a perennial, deeply taprooted herb with simple stems 30-100 cm tall, branching in the upper portions and covered in cobwebby and wooly white hairs. The plants form colonies by development of buds on the lateral roots. The lower leaf surfaces are covered in grayish wooly hairs. The upper leaf surfaces have a much reduced covering of hairs, making them appear green, and are free of spines. The basal leaves start out nearly entire and are replaced by lobed leaves as the plant matures. The cauline leaves are alternate, petiolate, the blades lanceolate to obovate, 5–20 cm long, 3-7 cm wide, undulate, deeply pinnately lobed to subentire and the margins are irregularly spinose. The leaves are larger at the bottom and become sessile and reduced in size upward. The terminal solitary heads have an involucre, 2-3 cm long, 1.5-2.5 cm wide, of 6-7 rows of bracts, each 5-9 mm long and about 3 mm wide with a prominent dorsal ridge and a spine tip, 2-4 mm long. The heads have only disc flowers, the corolla is purple to pink, 21-36 mm long with 5 lobes 5-9 mm long. the style is exerted from the corolla tube. The fruit is a brownish achene, 4-5 mm long and about 2 mm wide, with a pappus of 2-3 cm long hairs. Flodman’s thistle blooms from July into September in moist meadows, pastures and open sites throughout South Dakota.

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  Asteraceae : Conyza canadensis

  R. Neil Reese

  Conyza canadensis is an annual, herbaceous plant growing from 0.3 10 to 1.5 m tall, mostly simple or branching above if injured, with sparsely hairy stems. The simple, alternate leaves are sessile, narrowly oblanceolate to linear 2–10 cm long and generally <1 cm>wide, with entire to coarsely toothed margins. The leaves grow in a spiral up the stem and the lower ones often wither early. The inflorescence is a terminal cluster of flower heads 1 cm in diameter, with an involucre, of overlapping bracts, that is 3-4 mm long and green. Twenty to 30 ray flowers with white to pale purple ligules and a few yellow disc florets in the center. The fruit are hairy achenes with an abundant pappus. Horseweed is a weed in open cultivated and disturbed ground flowering from June through September throughout South Dakota.

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  Asteraceae: Dyssodia papposa

  R Neil Reese

  Dyssodia papposa is an erect to spreading, diffusely branching, annual herb,10-50 cm tall. The leaves are opposite near the base and alternate above, 1.5-5 cm long, pinnately parted and irregularly dotted with oil glands. The inflorescence consists of solitary heads arising singly from leaf axils and at the tips of branches heads, on very short peduncles, surrounded by a cylindrical to bell-shaped involucre, 6-10 mm long, with 6-12 principle bracts, free with several oil glands and several greenish orange to purplish shorter inside bracts. There are 8 or fewer ray yellow flowers with short ligules surrounding few to many dull yellow disk flowers. The fruit are stout, hairy achenes, 3-3.5 mm long with a pappus of about 20 scales, each with 5-10 bristles on the upper section. Fetid marigold blooms from July into September in open fields and disturbed areas of southern and western South Dakota.

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  Asteraceae : Echinacea angustifolia

  R. Neil Reese

  Echinacea angustifolia is a perennial herb with simple to branched stems which grow 10-60 cm in height. The stems are usually hairy, especially towards the top. The leaves are simple, alternate the margins entire and have 3-5 strong nerves running lengthwise. The lower leaves are petiolate, 5-30 cm long and 1-4 cm wide. The upper leaves becoming sessile and progressively smaller. The inflorescence consists of 1 or more heads, about 1.5 cm across, on long peduncles. The involucral bracts are 6-11 mm long and the conical receptacle 1.5-3 cm tall. The ray flowers have pink to light pink ligules 2-4 cm long and the disk flowers have a purplish corolla 6-8 mm long. The achenes are 4-5 kk long with a papery pappus that looks like a toothed crown. Echinacea angustifolia bloom from June to July on open rocky plains and prairies throughout South Dakota.