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  Asteraceae: Bidens cernua

  R. Neil Reese

  Bidens cernua is an obligate, warm-season annual wetland herbaceous forb supported by a shallow taproot system that frequently develops fibrous adventitious roots at the lower stem nodes when submerged. It typically achieves a plant height of 10 to 100 cm at maturity, displaying prostrate to erect stems that are soft, light green to reddish-purple, mostly glabrous or sparsely rough-hairy, and often branched. The leaf insertion is opposite and sessile, with the bases of opposing leaves often fused directly around the stem. The simple leaves are light green to medium green, 4 to 20 cm in length and 5 to 45 mm in width, with a linear-lanceolate or lanceolate shape, acuminate tips, and coarsely serrate margins. Both the upper and lower leaf surfaces are smooth and glabrous to nearly glabrous. Flowering occurs from July to October. The inflorescence consists of solitary terminal heads or loose clusters born on peduncles 1 to 7 cm long. Individual heads are radiate or occasionally discoid, measuring 1.2 to 2.5 cm across, and typically droop or nod as they age. The hemispheric involucre features two distinct rows of dissimilar phyllaries: the outer series contains 5 to 9 leaf-like, linear-lanceolate bracts measuring 1 to 3 cm long that are widely spreading or reflexed, while the inner series contains 6 to 10 ovate-lanceolate bracts measuring 4 to 10 mm long with yellowish or clear scarious margins. The pappus consists of 4 straight awns measuring 2 to 4 millimeters long, which are lined with tiny, downward-pointing barbs. There are 6 to 8 yellow ray florets measuring 8 to 15 mm long (though sometimes absent) surrounding a dense central disk of numerous fertile yellow disk florets with corollas 3 to 4 mm long. The flowers possess 5 stamens featuring dark yellow to brownish linear anthers fused into a tube around the style. The single pistil contains a inferior ovary with a slender style that splits into 2 distinct, recurved stigmas. The fruit is a wedge-shaped, 4-angled, front-to-back compressed achene (cypsela) measuring 5 to 7 millimeters long, which turns dull dark brown to blackish purple. The achenes reach maturity from late August through October. Nodding beggarticks is native to South Dakota, where it can be found distributed across wet habitats statewide, including marshes, wet ditches, stream banks, lake edges, sedge meadows, and exposed mud flats.

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  Asteraceae: Bidens vulgata

  R. Neil Reese

  Bidens vulgata is an annual herb with a fibrous root system, reproducing exclusively by seed. The stems are erect, branched above, and can reach 30–120 cm tall, often with angled or ridged surfaces and sometimes rough to the touch. Leaves are opposite, pinnately compound with 3 to 7 lance-shaped leaflets; leaflets are 3–10 cm long, with serrated margins and pointed tips, the central leaflet usually the largest. Petioles are 1 to 5 centimeters long. Both stem and leaf surfaces may be sparsely to moderately hairy. Flowering occurs from late summer to fall. The inflorescence is a loose or clustered array of small, yellow, daisy-like flower heads, each with a few inconspicuous yellow ray florets (sometimes absent) and numerous yellow disc florets. The involucral bracts are green, narrow, and often extend beyond the flower head. Flowers have five lobes; stamens number five with anthers fused into a tube around the ovary. The pistil comprises a single ovary with a bifid style. Fruits are flattened, two- to four-awned achenes ("sticktights") 4–8 mm long, brown to black at maturity, with barbed awns that easily attach to fur or clothing for dispersal. Tall Beggarticks is native to South Dakota and typically found in moist, disturbed soils such as ditches, streambanks, floodplains, wet meadows, and along roadsides, most common in the eastern and central portions of the state.

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  Asteraceae: Carduus nutans

  R. Neil Reese

  Carduus nutans is a biennial (sometimes annual or short-lived perennial) herb in the Asteraceae family. It develops from a stout, fleshy taproot and does not reproduce asexually via stolons or rhizomes. During its first year, it forms a large basal rosette of spiny, deeply lobed leaves, each up to 40 cm long, with white, woolly undersides and sharp, yellowish spines along the margins. In its second year, it produces a single, stout, erect, and often branched stem, usually 60–200 cm tall, with conspicuous wings (spiny extensions) running down from the leaf bases. Leaves are alternate and deeply lobed with spiny margins; basal and lower leaves can be 10 to 30 centimeters long and 5 to 10 centimeters wide, narrowing upward on the stem. Petioles are winged and spiny-edged. Stems and leaves are covered with cobwebby hairs, especially when young. Flowering occurs from June to September. Inflorescences are solitary or in small clusters at the stem tips; each is a large, pendulous (nodding) flower head, 3–7 cm across. The involucre consists of several series of broad, rigid, spiny-tipped green bracts (phyllaries) about 2 to 3.5 centimeters long and 0.5 to 1 centimeter wide, forming a spiny protective cup around the flower head base. Each flower head contains numerous tubular florets with 15 to 25 bright purple to pink ligulate corollas, each ligule approximately 1.5 to 2.5 centimeters long and 3 to 5 millimeters wide. Florets have five lobes; stamens number five with anthers fused around the ovary. The pistil consists of a single ovary with a two-branched style. The fruit is a small, ribbed achene about 4 to 5 millimeters long topped with a pappus of fine hairs facilitating wind dispersal. Fruits mature late summer into fall. Musk thistle is an introduced species in South Dakota, most common in disturbed sites, roadsides, pastures, fields, and rangelands, and is found statewide but especially abundant in the east and central regions.

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  Asteraceae: Centaurea stoebe

  R. Neil Reese

  Centaurea stoebe is a biennial or short-lived perennial forb in the Asteraceae family. It grows from a deep, stout taproot. Plants form a basal rosette of deeply divided, grayish-green leaves in the first year, with leaves 5–25 cm long, narrow and deeply pinnately lobed with irregular, toothed margins, giving them a somewhat fern-like appearance. In the second year, one or more erect, branched stems arise from the rosette, typically 40–120 cm tall; stems are slender, rough to the touch, and covered with short, stiff hairs. Cauline leaves are smaller, linear or narrowly lanceolate, becoming progressively smaller and simpler in shape, often lanceolate or narrowly elliptic, and less deeply lobed or sometimes nearly entire, typically ranging from 3 to 7 cm in length. Leaf surface texture is mostly sparsely hairy with a rough feel. Flowering occurs from June to September. Inflorescences are solitary or in loose clusters at the ends of stems, each composed of a single flower head (capitulum) atop a short stalk. Each head is 1–2 cm across, containing numerous tubular disc florets that are pink to purple in color. Each floret has a five-lobed corolla, with lobes that are slightly spreading, presenting a somewhat thistle-like appearance. The involucre surrounding the flower head is characterized by several layers of overlapping bracts, which are brownish to black with distinctive dark, purplish to black tips, often spotted, and fringed with fine hairs that give a "spotted" look—a key trait for species identification. These bracts typically measure about 1.5 to 2.5 cm long. Fruits are small, brown, ribbed achenes (2–3 mm) with a short, fringed pappus, maturing from late summer into fall. Spotted knapweed is an introduced species classified as a noxious weed in South Dakota, commonly invading roadsides, rangelands, pastures, fields, gravelly or sandy soils, and

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  Asteraceae: Cirsium arvense

  R. Neil Reese

  Cirsium arvense is a perennial herb. It grows from a deep, extensive, creeping root system with horizontal rhizomes, enabling vigorous asexual reproduction and the formation of dense colonies. The erect stems are slender, ribbed, and mostly unbranched (except near the inflorescence), typically ranging from 30–120 cm tall, and sparsely hairy to nearly glabrous. Leaves are alternate and lanceolate to linear-lanceolate, typically 5–30 cm long and 2–7 cm wide, deeply lobed, with irregularly toothed margins tipped by sharp yellowish spines; upper leaf surfaces are green and nearly smooth, while the lower surfaces are paler and may be thinly hairy. Both basal and cauline leaves are well developed; basal leaves are often larger and may wither by flowering time. Flowering occurs from mid-June to September. The inflorescences are clusters of small (1–2 cm) heads at the ends of stems and branches. Plants are dioecious, with male and female flowers on separate plants. Flower heads are egg-shaped, each with a series of overlapping green to purplish spiny involucral bracts, which are ovate-lanceolate and sharply pointed. The corollas are composed only of tubular disc florets, 15–20 mm long, with petals that are deeply divided into about five lobes at the tip, giving the corolla a frilled appearance and typically lavender to pink (sometimes white), fragrant, and with long, deeply lobed styles. Male heads produce pollen, while female heads are seed-producing. The fruit is a small, brownish, ribbed achene (2–4 mm) with a tuft of white, hairlike pappus for wind dispersal, maturing from late summer into fall. Canada thistle is an introduced, aggressive noxious weed in South Dakota, invading prairies, cropland, pastures, roadsides, disturbed sites, and riverbanks. It is statewide, particularly abundant in moist, disturbed soils and perennial cropping systems.

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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: Coreopsis tinctoria

  R. Neil Reese

  Coreopsis tinctoria is an annual herb with a fibrous root system. Stems are erect, slender, branched, and typically 30–90 cm tall, with a sparse covering of fine hairs. Leaves are opposite to alternate, highly variable, simple to pinnately divided, linear to lanceolate, leaflets 1–4 cm long and 1–5 mm wide, with entire or slightly toothed margins; both basal and cauline leaves are present. Basal leaves tend to be larger and more deeply lobed, while upper leaves are smaller and simpler, but basal leaves are often lost by flowering. Flowering occurs from June to September. The inflorescences are terminal and bear large, solitary flower heads (capitula) about 3–5 cm across. Each flower head is composed of bright yellow ray florets each approximately 15–30 mm long and 5–10 mm wide, with red to maroon centers. The central disc florets that are deep maroon to purple, tubular, about 5–7 mm long, and very numerous, creating a dense, contrasting center. Flowers are bisexual, with 5 fused petals in ray florets and tubular disc florets with 5 lobes, multiple stamens, and a single pistil. Fruit is an achene, brown to black, about 3–4 mm long, maturing in late summer. Plains coreopsis is native to South Dakota and thrives in open prairies, roadsides, disturbed areas, and dry upland soils, distributed statewide but more abundant in the eastern and central regions.

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  Asteraceae: Cyclachaena xanthiifolia

  R. Neil Reese

  Cyclachaena xanthiifolia is a summer annual herbaceous forb that develops from a distinct taproot. Giant sumpweed typically grows to a height of 30 to 200 cm, featuring a stout, erect, angular stem that is unbranched below but heavily branched within the upper inflorescence. The lower portion of the stem is completely hairless, while the upper sections bear fine, sticky, glandular hairs. Leaf insertion is primarily opposite along the lower stem but can shift to an alternate arrangement near the upper flower clusters. The leaves are simple, broadly ovate to triangular, and sometimes shallowly three-lobed. They exhibit a light grayish green to medium green color, with blades measuring 6 to 12 cm long and 5 to 12 cm wide with coarsely or doubly toothed margins. The upper leaf surface is slightly rough-textured with a sparse covering of straight, stiff, appressed hairs, whereas the lower surface is distinctly paler and silky-soft due to a dense layer of long, soft, appressed hairs. Petioles are present and well-developed, 1 to 7 cm in length. Flowering occurs from July through October. The inflorescence consists of numerous small, drooping, disk-shaped heads arranged in dense, elongated, branching panicles arising from the upper leaf axils and terminal stems. The cup-like involucre at the base of each head measures 1.5 to 3 mm high. It features 5 outer herbaceous phyllaries (bracts) that are broad and covered in fine hairs, and 5 inner scarious to membranous, glabrous phyllaries. A pappus is entirely absent. Staminate (male) central florets feature fused petals forming a white to pale yellow tubular corolla roughly 2 to 2.5 mm long with terminal teeth, while the outer pistillate (female) florets have an obsolete or heavily reduced, tiny whitish corolla tube measuring only 0.1 to 0.5 mm long. Each staminate floret contains 5 stamens with filaments fused into a tube and free, white to pale yellow anthers arranged closely in a ring. The pistil structure consists of a single inferior ovary per pistillate floret, terminating in a style that branches into 2 short, thread-like stigmas, whereas staminate florets retain a single sterile, undivided style. The fruit is a smooth, egg-shaped to triangular cypsela (achene) measuring 2 to 3 mm long, turning dark brown to nearly black as it reaches maturity between August and October. Giant sumpweed is native to South Dakota and is widely distributed across the state, commonly occupying high-moisture or disturbed habitats such as floodplains, bottomlands, riverbanks, roadsides, and fertile agricultural fields.

  Synonym: Euphrosyne xanthiifolia

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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.

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  Asteraceae : Ericameria nauseosa

  R. Neil Reese

  Ericameria nauseosa is a woody perennial shrub 0.5-3 m tall, having a woody base and gray green younger branches with a dense covering of appressed hairs that can look like bark until one lightly scrapes the surface. The smooth to somewhat hairy leaves are alternate, sessile or nearly so, linear to narrowly linear lanceolate, 2-6 cm long and 1-2 mm wide and marked by 1 t0 3 nerves. The inflorescence is a series of rounded terminal compound cymose clusters of heads. The pungent-smelling heads are surrounded by 20-25 bracts in vertical ranks 6-8 mm tall and contain 5 yellow disk flowers. The corolla is 6-9 mm long with 5 lobes up to 2 mm in length. The fruit are 5-angled achenes about 5 mm in length with a pappus of numerous bristles. Rubber Rabbitbrush blooms from August to October on hills and high plains predominantly in western South Dakota.

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  Asteraceae: Erigeron canadensis

  R. Neil Reese

  Erigeron canadensis is a fast-growing, annual or short-lived perennial herb growing from a fibrous root system, with slender stems that are typically 30 to 150 tall, erect, branched, and often sparsely hairy to nearly glabrous. Leaves are alternate, narrowly lanceolate to linear, measuring 2 to 10 cm long and 0.5 to 1.5 cm wide, with short petioles or sessile bases and finely serrate to entire margins. Flowering occurs from late summer to fall (July–October), producing open, branching panicles of numerous small flower heads . Each flower head is about 1–2 cm across, with 40–100 white to pale lavender ray florets, 2 to 4 mm long, surrounding yellow disc florets. Flowers are bisexual, with five-lobed corollas, 5 stamens fused by their anthers into a tube surrounding the style, and a single pistil with a slender style bifurcated at the tip into two slender, elongated stigmatic branches. The involucre is composed of several series (3 to 4 rows) of narrow, greenish to pale bracts (phyllaries) that are lanceolate and often slightly membranous with finely fringed or ciliate margins, forming a cup-shaped structure surrounding the base of the composite flower head. The fruit is a small, ribbed achene about 1 to 2 millimeters long with a pappus of fine bristles aiding wind dispersal. Seeds mature in early fall. Canadian horseweed is native to North America and widespread throughout South Dakota, commonly found in disturbed sites, roadsides, fields, and open areas.

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  Asteraceae: Erigeron divergens

  R Neil Reese

  Erigeron divergens is annual to weakly perennial herb with erect stems, 10–40 cm long, often branched at the base from a simple caudex, the stems covered with short stiff and/or glandular hairs. . Leaves are alternate and mostly basal, linear to narrowly lanceolate or spatulate, measuring 2 to 7 cm long and 3 to 12 mm wide, with petioles from sessile up to 2 cm, margins are entire to slightly toothed. These leaves are usually deciduous by flowering. The simple, cauline leaves are reduced in size, linear to lanceolate, and tapering; leaves often have a silvery or bluish-green hue due to fine hairs. Flowering occurs from late spring through fall (May–September). Inflorescences consist of clusters or solitary flower heads with both ray and disc florets. Flowers are bisexual. Each flower head contains 70 – 150 ray flowers with blue to pink to white ligules, 5-10 mm long and numerous yellow disk flowers, 2–3 mm long. These florets have tubular corollas with five lobes, stamens form a tube around the ovary, and there is a single pistil with bifid style tip. The involucre is composed of several (3 to 5) series of overlapping greenish to reddish, narrow, lanceolate bracts (phyllaries) with membranous margins, a brown midvein, and often with fine hairs, forming a bell-shaped to cup-shaped structure surrounding the flower base. The fruit are achenes about 1 mm long. Spreading fleabane is native to South Dakota, found in dry prairies, open woodlands, rocky slopes, and disturbed sites, widely distributed but most common in western and central parts of the state.

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  Asteraceae: Erigeron flagellaris

  R. Neil Reese

  Erigeron flagellaris is a low, mat-forming perennial herb growing from a fibrous root system and spreads asexually by slender, trailing stolons or “whips,” which root at nodes to form new plants. Stems are slender, prostrate to ascending, typically 5–15 cm tall but spreading laterally much farther. Leaves are alternate, narrow, linear to lanceolate, 1–4 cm long and 1–3 mm wide, mostly basal or along the lower stem, with smooth margins and a somewhat rough texture and covered with fine hairs giving a gray-green appearance. The few cauline leaves that are present are smaller, and scale-like. Flowering occurs in spring and summer (April–July). Each flower head is about 1–1.5 cm wide, with 15–35 narrow white to pale lavender ray florets surrounding numerous yellow disc florets. The ray flowers are strap-shaped, about 5–8 mm long and 1–2 mm wide. Disc flowers are tubular, bright yellow, and fertile with five stamens fused into a tube around the style. The style ends in two slender, slightly hairy stigmatic branches. The involucre phyllaries are narrow, lanceolate, measuring about 5–10 mm long, with pointed tips and somewhat hairy. The fruit is a small achene with a pappus of fine bristles for wind dispersal, maturing in early summer. Whip fleabane is native to South Dakota, growing in dry open woods, rocky slopes, grasslands, and sandy soils, especially in western and central regions.

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  Asteraceae: Erigeron glabellus

  R. Neil Reese

  Erigeron glabellus is a biennial or short-lived perennial herb arising from a simple caudex supported by a shallow, fibrous root system that occasionally develops short, weak rhizomes. The plant reaches a height of 15 to 70 cm, developing 1 to 8 erect or ascending stems that range from nearly glabrous with appressed hairs to densely hirsute with spreading hairs. Leaves are alternate along the stem; the basal leaves are simple, green, oblanceolate to spatulate, measuring 5 to 15 cm long and 4 to 20 mm wide, narrowing into a distinct winged petiole up to 8 centimeters long. The upper cauline leaves transition to sessile (lacking a petiole) and become progressively smaller, lanceolate to linear, with mostly smooth to sparsely appressed-hairy upper and lower surfaces. Flowering occurs from June through August, producing 1 to 15 showy, daisy-like heads arranged in loose, terminal corymb-like arrays or solitary on long stalks. It has a hemispheric involucre measuring 5 to 9 mm long and 10 to 20 mm wide, composed of 2 to 3 series of linear, green, often dark-tipped, hirsute bracts. The florets have a persistent, double-series pappus, where the outer series consists of short, inconspicuous scales and the inner series features 20 to 30 fragile, bristly, tawny hairs measuring 5 to 7 mm long. There are 125 to 175 dense, narrow, pistillate ray florets measuring 8 to 15 mm long, spreading flat in hues of lavender, pink, or white. At the center sit numerous yellow, bisexual, 5-lobed disc flowers measuring 4 to 5 mm long, within which lie 5 fused stamens bearing yellowish anthers, closely surrounding a single pistil with a deeply bifid style and elongated stigma branches. The resulting fruit is a flattened, oblong, tan to light brown, 2-nerved cypsela (achene) measuring 1.5 to 2.5 mm long, which reaches full maturity from late August through October. Smooth fleabane is native to South Dakota, where it is primarily distributed across the western counties, most notably within the Black Hills and Badland regions, inhabiting moist to dry grasslands, meadows, open woodlands, stream sides, and gravelly hillsides.

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  Asteraceae: Erigeron philadelphicus

  R. Neil Reese

  Erigeron philadelphicus is a perennial herb that typically grows 30–90 cm tall with erect, slender stems that may be branched or unbranched and are covered with fine hairs (pubescent). The plant has a fibrous root system and may spread by short rhizomes. Leaves are alternate and simple, ranging from lanceolate to ovate, 5–15 cm long, with coarsely smooth to toothed margins and a rough texture. Both basal and cauline leaves are present, basal leaves forming a rosette early in the season and often dwindling by flowering time. Basal and lower leaves have petioles, while upper leaves may clasp the stem. Flowering occurs from late spring to early fall (May–September). Inflorescences are composed of multiple small, daisy-like flower heads arranged in loose clusters or panicles. Each flower head is about 1–2 cm across and contains 40–70 narrow white to pale pink ray florets surrounding numerous bright yellow disc florets. The ligule phyllaries are arranged in 2–3 overlapping series, broadly lanceolate to ovate, about 7–12 mm long, with pointed tips and a slightly hairy texture. The ray flowers are strap-shaped, about 7–12 mm long and 1.5–3 mm wide, mostly sterile or female, serving to attract pollinators. The disc flowers are tubular, perfect (bisexual), 2.5 to 4 millimeters in length. The corolla tube of each disc floret has five distinct lobes that spread slightly as the flower matures, forming a small, open star-shaped mouth, with five stamens fused by their anthers into a tube around the style. The style extends through the anther tube, its tip divides into two slender, slightly hairy stigmatic branches. The fruit is a small achene with a fluffy pappus allowing wind dispersal, maturing in late summer. Philadelphia fleabane is native to South Dakota and common in open woods, meadows, roadsides, and disturbed sites statewide.

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  Asteraceae : Erigeron pumilis

  R. Neil Reese

  Erigeron pumilus is a taprooted perennial with a simple to branched caudex with ascending to erect stems, 5–30 cm tall covered with long, spreading hairs, many of which are glandular toward the top. The basal and alternate cauline leaves are simple, entire, the blades are linear- to narrowly oblanceolate, 15–80 mm long and up to 8 mm wide. The inflorescence is a cluster of heads (1-many) that are 7-15 mm in diameter. The involucre is 4–8 mm high, the bracts in 2 to 4 series, with minutely glandular hairs and a brownish midvein. Each head has 50–100 white to pinkish (occasionally bluish) ray flowers, the ligules 5–12 mm long. Corollas of the disk flowers are yellow and 2–5 mm long. Achenes are 1–2 mm long with a pappus of 2 rows of bristles. Shaggy fleabane blooms from June into August on dry high plains and prairies predominantly in west river South Dakota.

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  Asteraceae: Erigeron speciosus var. macranthus

  R. Neil Reese

  Erigeron speciosus is a perennial herbaceous plant known for its showy, daisy-like flower heads. It typically grows 30–90 cm tall with erect, simple to branched, moderately hairy stems arising from a woody base or short rhizomes. Leaves are alternate, lanceolate to ovate-lanceolate, 5–15 cm long and 1–5 cm wide, with smooth or slightly toothed margins and a rough texture. Lower leaves often have petioles, while upper leaves may clasp the stem.

  Flowering occurs from mid-summer to early fall (July–September). Inflorescences are composed of numerous large, showy flower heads with lavender to purple ray florets and yellow disc florets, arranged in loose clusters or solitary at stem tips. The involucre consists of a series of green to reddish-green overlapping bracts that are broadly lanceolate to ovate, 10–15 mm long, with pointed tips and a somewhat hairy or glandular texture. Each flower head contains 60–120 bright lavender to pale purple, occasionally white ray florets that are strap-shaped, about 12–18 mm long and 2–4 mm wide, mostly sterile or female, primarily serving to attract pollinators. The disc florets are tubular, perfect (bisexual), bright yellow, 3–4.5 mm in length. The corolla tube has five lobes that spread slightly as the flower matures. The five stamens are fused by their anthers into a tube surrounding the style. The style extends through the anther tube, the tip of the style divides into two slender, slightly hairy stigmatic branches. Fruit is a small achene with a pappus of many fine, white bristles and matures in late summer. Showy fleabane is native to South Dakota, occurring in montane meadows, open woods, and rocky slopes, mainly in western and central parts of the state.

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  Asteraceae: Erigeron strigosus

  R. Neil Reese

  Erigeron strigosus is an annual or biennial herbaceous plant that typically grows 30–80 cm tall with erect, slender, and often branched stems. The stems and leaves are covered with fine, stiff hairs (strigose), giving the plant a rough texture and a slightly grayish-green appearance. Leaves are alternate, narrow lanceolate to linear, 3–10 cm long and 0.5–2 cm wide, with entire to coarse toothed margins; basal leaves have petioles and form a rosette early in the season and usually wither by flowering time, while cauline leaves are smaller and clasping. Flowering occurs from summer to early fall (June–September). Inflorescences are composed of numerous small flower heads borne in loose clusters or solitary at stem tips. The phyllaries of the involucre are arranged in 2–3 overlapping series, narrow and lanceolate, about 5–8 mm long, with pointed tips and a rough, hairy texture. Their color ranges from green to reddish green, sometimes with translucent margins. Each flower head is 1–1.5 cm across, with white to pale pink or lavender ray florets surrounding yellow disc florets. Each flower head contains 30–60 narrow white to pale lavender ray florets surrounding numerous bright yellow disc florets. The ray florets are strap-shaped, about 5–10 mm long and 1–2 mm wide, mostly sterile or female, serving to attract pollinators. The disc florets are tubular, perfect (bisexual), measuring about 2.5–3.5 mm in length. The corolla has five lobes that spread slightly as the flower matures. The disc florets have five stamens fused by their anthers into a tube surrounding the style. The style extends through the anther tube and is divided into two slender, slightly hairy stigmatic branches. The fruit is a small achene with a pappus of fine bristles, maturing in late summer. Prairie fleabane is native to South Dakota and common in prairies, roadsides, fields, and disturbed sites statewide.

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  Asteraceae : Eupatorium perfoliatum

  R. Neil Reese

  Eupatorium perfoliatum is a perennial herb arising from a rhizome, with stems, covered with hairs, that grow from 40 to 150 cm tall. The simple, opposite leaves clasp the stems. The blades are broad at the base and taper to a point at the tip, 7-20 cm long and up to 4 cm wide, with toothed margins and hairy lower sides. The inflorescence is made up of flat-topped clusters of heads. Each head has a 4-6 mm involucre of overlapping bracts in several series. There are 9-23 white disk flowers that produce 5-sided achenes that have a bristly pappus. Boneset blooms in August and September in damp prairies and bogs in the eastern edge of South Dakota.

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  Asteraceae: Eutrochium maculatum

  R Neil Reese

  Eutrochium maculatum is a perennial herb growing from 40 to 200 cm tall. The stems are variously purple spotted to completely purple. The simple leaves are in whorled in groups of 4 or 5, narrowly lanceolate to lance-ovate, usually with a short petiole. The blades are 6-15 cm long and 2-8 cm wide, with toothed margins. The inflorescence is a flat-topped cluster of heads with a 6-9 mm involucre of overlapping bracts. Each head contains 8-22 rose to purple disc flowers. Fruit are 5-sided achenes with a pappus of bristles. Spotted joe-pye weed blooms from July into September and is found in marshes, fens, swamps, ditches, and wet fields in eastern and western South Dakota.

  Synonym: Eupatorium maculatum

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  Asteraceae: Gaillardia aristata

  R Neil Reese

  Gaillardia aristata is a perennial herb with 1 to several hairy stems, 30-60 cm tall from a taproot. The weakly petiolate leaves are basal and alternate on the stem, oblong to lanceolate-ovate, 5-15 cm long, up to 2.5 cm wide, with the margins various from entire to toothed to somewhat pinnately lobed. The inflorescence consists of solitary to a few heads on long peduncles with an involucre of 2-3 series of hairy, pointed bracts, 1-2 cm long and with bristly hairs on the receptacle that are longer than the achenes. The ray flowers have 3-parted ligules, yellow with a purplish base and 1-3 cm long. The disk flowers are purple to brownish purple, hairy toward the top, with a style that is exerted from the corolla. The fruit are achenes about 4 mm long and covered with long hairs. Blanketflower blooms from June into August on open plains and prairies of northeastern and western South Dakota.

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  Asteraceae: Grindelia squarrosa

  R. Neil Reese

  Grindelia squarrosa is a perennial herbaceous or short-lived perennial plant that grows from a deep taproot, known for its sticky, resinous foliage and distinctive flower heads. It typically grows 30–90 cm tall with erect, branching stems. Leaves are alternate, sticky, glandular, and covered with resinous exudates giving a sticky texture and shiny appearance, sessile, lanceolate to ovate-lanceolate in shape, typically measuring 5 to 15 cm long and 1 to 4 cm wide, with smoothed or entire margins, a rounded to slightly tapered base and a generally acute or pointed tip. Leaves tend to be narrower and more lance-shaped on the upper stems, while the lower leaves are broader and sometimes more ovate. Flowering occurs from mid-summer to early fall (July–September). Inflorescences are large, solitary flower heads 3–5 cm across, with bright yellow ray florets surrounding a dense cluster of yellow disc florets. The involucre consists of several series of broad, pointed phyllaries that are green to reddish-green, often with resinous glands. Each flower head contains numerous yellow ray florets surrounding a dense cluster of yellow disc florets. The ray florets are strap-shaped, about 12–20 mm long, mostly sterile or female, serving to attract pollinators. The disc florets are tubular, perfect (bisexual), about 4–5 mm long, with a corolla tube lobed into five spreading lobes. The disc florets have five stamens fused by their anthers into a tube around the style. The style extends through the anther tube that divides into two slender, slightly hairy stigmatic branches. The flowers emit a distinctive resinous scent. Fruit is an achene with a pappus of fine bristles, maturing in late summer. Curlycup gumweed is native to South Dakota, commonly found in dry, disturbed areas, roadsides, grasslands, and open woods statewide.