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  Violaceae: Viola sororia

  R. Neil Reese

  Viola sororia is a perennial, herbaceous plant with a fibrous root system and short, creeping rhizomes, often forming dense patches. Mature plants typically reach 10–30 cm in height. Stems are slender, erect or ascending, and mostly leafless except near the base. Leaves are alternate, simple, heart-shaped to ovate, 3–10 cm long and wide, with crenate to serrate margins and an acute to rounded tip. The upper leaf surface is medium green and glabrous or sparsely hairy, while the lower surface is paler and sometimes hairy. Petioles are long, 5–15 cm, often hairy. Stipules are present, ovate to lanceolate, 5–15 mm long, often toothed or fringed. Flowering occurs from April to June, with solitary, showy, zygomorphic flowers, 15–25 mm wide, born on slender peduncles rising above the foliage. The flowers have five petals; the lower petal is usually spurred and about 8 to 15 mm long and 3 to 6 mm wide, while the lateral petals measure 7 to 12 mm long and 4 to 7 mm wide, often with bearded bases. Sepals are lanceolate, green, generally 6 to 10 millimeters long and 1.5 to 3 millimeters wide. There are five stamens with yellow anthers arranged around the pistil, with filament bases forming nectar-producing spurs near the ovary. The pistil has a single, slender style ending in a capitate stigma. The fruit is a small, ovoid capsule, 5–12 mm long, splitting open at maturity from, June to August, to release numerous small seeds often equipped with elaiosomes encouraging ant dispersal. containing numerous tiny seeds, maturing. Common blue violet is native to South Dakota and occurs in moist woodlands, meadows, lawns, and shaded disturbed areas, preferring well-drained to moist, loamy soils under partial to full shade.

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  Acoraceae: Acorus americanus

  R. Neil Reese

  Acorus americanus is a grass-like perennial herb, which grows 90-150 cm in height. The plant is strongly rhizomatous. The leaves are entire, sword shaped and erect. Sweet flag has a spadix that is 4-9 cm long with light brown greenish-brown perfect flowers that are enclosed by a leaf-like spathe. The perianth has 6 short segments, there are 6 stamens, and the pistil contains 2-3 locules. The fruit is a small capsule containing 2-3 seeds. Flowering occurs from May to July. This species is commonly found in swamps and marshes throughout South Dakota.

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  Cyperaceae: Carex brevior

  R. Neil Reese

  Carex brevior is a perennial sedge in the Cyperaceae family. It grows from a dense, fibrous root system with short rhizomes, sometimes forming small clumps but not extensive sods. The stems (culms) are upright, slender, triangular in cross-section, and usually 30–70 cm tall, smooth or minutely rough below the inflorescence. Leaves are mostly basal, grass-like, flat, and 2–5 mm wide, with sheathing bases and rough margins. Cauline leaves are few, shorter than the culms, and often drooping. Flowering occurs from late spring to early summer (May–July). Inflorescences are terminal, composed of 2–5 short, dense, cylindrical spikes. The terminal spike is usually staminate (male), while the lower spikes are pistillate (female), but sometimes spikes are androgynous. Each spike is 1–3 cm long and 5–7 mm wide. Each pistillate flower is enclosed in a sac-like perigynium, which is green to brown, inflated, and beaked. The perigynia are 3–5 mm long and 1–2 mm wide, with a short, thick beak. The achene (seed) is lens-shaped, brown, and 1.5–2 mm long, maturing in early to midsummer. Shortbeak sedge is native to South Dakota, occurring in dry to mesic prairies, open woodlands, roadsides, and disturbed soils, and is found statewide, especially in upland prairies and open meadows.

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  Cyperaceae: Carex hoodii

  R. Neil Reese

  Carex hoodii is a perennial sedge in the Cyperaceae family. It grows from a dense, fibrous root system with short rhizomes, forming loose tufts or small clumps rather than extensive sods. Stems (culms) are upright, slender, sharply three-angled, and range from 20–60 cm tall, smooth below but often rough near the inflorescence. Leaves are mostly basal, narrow, flat or slightly folded, 1–3 mm wide, and shorter than the culms, with rough margins and tight basal sheaths. Flowering occurs from late spring to mid-summer (May–July). Inflorescences are terminal and consist of 2–4 short, narrow spikes (each 1–2.5 cm long). The terminal spike is commonly staminate (male), while the lower spikes are pistillate (female), though some spikes may be androgynous. Pistillate flowers are enclosed in a sac-like perigynium, which is green to brown, ovoid to ellipsoid, 2.5–4 mm long and 1–1.5 mm wide, with a short, straight beak. The achene (seed) is lens-shaped, brown, and about 1.5 mm long, maturing in early to mid-summer. Hood’s sedge is native to South Dakota, typically found in dry to mesic prairies, open pine woods, rocky slopes, and sandy soils, and is most frequent in the Black Hills, Coteau des Prairies, and northern and western uplands.

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  Cyperaceae: Carex muehlenbergii

  R. Neil Reese

  Carex muehlenbergii is a perennial sedge growing from a fibrous root system with slender, short rhizomes, forming loose tufts but not dense sods. Stems (culms) are upright, sharply three-angled, and range from 20–60 cm tall, usually smooth or sometimes slightly rough near the inflorescence. Leaves are mostly basal, narrow (1–3 mm wide), flat or slightly folded, and shorter than or about equal to the culms, with rough margins and sheathing bases. The ligule is a thin, translucent band about 1 to 2 millimeters high, often acute and sometimes with frayed edges. Flowering occurs from late spring to early summer (May–July). The terminal inflorescence consists of 2–5 short, cylindrical spikes, with the top (terminal) spike usually staminate (male) and lower spikes pistillate (female), though some may be androgynous. Each flower has scale-like bracts subtending small florets. Stamens number three with slender filaments and pollen-bearing anthers; the pistil has a single ovary with one style and two branching stigmas. Pistillate flowers are enclosed in a sac-like perigynium, which is green to brown, ovoid, 2.5–4 mm long and about 1 mm wide, with a short, straight beak. The achene (seed) is lens-shaped, brown, and about 1.5 mm long, maturing in early to midsummer. Sand sedge is native to South Dakota, most commonly found in dry, sandy prairies, open woodlands, sand dunes, and disturbed sandy soils, and is widespread but especially abundant in sandy uplands and the central and western parts of the state.

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  Cyperaceae: Carex praegracilis

  R. Neil Reese

  Carex praegracilis is a perennial sedge in the Cyperaceae family. It grows from a dense, fibrous root system with long, creeping rhizomes, forming loose to dense sods and spreading readily by vegetative means. Stems (culms) are upright, slender, sharply three-angled, usually 20–70 cm tall, and smooth or slightly rough near the inflorescence. Leaves arise mostly from the base, with sheathing leaf bases that are smooth and light brown to tan and may be tinged reddish-brown. Leaf blades are narrow and flat, typically 2 to 4 mm wide often shorter than the culms, with rough margins. The ligule is a short, membranous, translucent structure about 1 to 2 millimeters long, often acute or truncate with smooth or slightly jagged edges, located at the junction of leaf blade and sheath. Flowering occurs from late spring to early summer (May–July). Inflorescences are terminal, composed of 2–5 short, cylindrical spikes, slender, erect, bearing numerous small spikelets clustered at the top of the stems. The species is usually monoecious, with staminate (male) flowers in terminal spikelets and pistillate (female) flowers in lateral or lower spikes, though some may be androgynous. Floral scales subtend florets with three stamens in male flowers and a single ovary with one style (dividing into two stigmas) in female flowers. Pistillate flowers are enclosed in a sac-like perigynium, which is green to brown, 2.5–4 mm long, and about 1 mm wide, with a short, straight beak. The achene (seed) is lenticular, brown, and about 1–1.5 mm long, maturing from early to midsummer. Clustered field sedge is native to South Dakota, commonly found in moist to wet meadows, prairies, roadside ditches, alkaline flats, and disturbed soils. It is distributed statewide but is especially abundant in low, moist sites and along roadsides.

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  Cyperaceae: Cyperus odoratus

  R. Neil Reese

  Cyperus odoratus is an annual or short-lived perennial sedge with a fibrous root system and sometimes tuberous rhizomes, allowing moderate vegetative spread. The erect stems (culms) are slender, triangular in cross-section, and range from 10 to 80 cm tall. Leaves are grass-like, alternate, linear, and smooth to rough, typically 5–30 cm long and 2–5 mm wide, with rough margins and sheathing bases that wrap closely around the stem base. The ligule is short and inconspicuous, often appearing as a small fringe of hairs or a thin membrane. Flowering occurs from summer through fall (June–October). Inflorescences are compound umbels with multiple rays, each bearing clusters of small spikelets. Spikelets are lanceolate to ovate, 2–5 mm long and consist of many brown to purplish-brown flowers covered by overlapping scales. Flowers have three stamens and a pistil with three stigmas. The fruit is a small, lens-shaped achene, about 1–2 mm long, brown at maturity, ripening from late summer into fall. Fragrant flatsedge is native to South Dakota, occurring in wetlands, marshes, ditches, riverbanks, and moist disturbed soils statewide, with higher concentrations in eastern and central regions.

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  Cyperaceae: Eleocharis compressa

  R. Neil Reese

  Eleocharis compressa is an annual to perennial herbaceous sedge from a fibrous root system. Stems (culms) are erect, slender, and usually laterally compressed (flattened) in cross-section, ranging from 10–50 cm tall. Leaves are reduced to narrow sheaths at the base of the stem, with no true leaf blades. The ligule is typically absent or represented by a small membrane or fringe of hairs at the junction of sheath and stem. Flowering occurs from summer to early fall (July–September). The inflorescence consists of a single terminal spikelet about 5–15 mm long, narrow and cylindrical, containing numerous tiny flowers. Each flower is subtended by a scale (a modified bract) about 2–3 mm long, ovate to lanceolate in shape, greenish to brownish in color. Flowers have no petals or sepals but possess three stamens and a single pistil. The fruit is a small, lens-shaped achene, about 1–2 mm long, brown at maturity, ripening late summer into fall. Flat-stem spike-rush is native to South Dakota, commonly occupying wetlands, shallow ponds, marshes, and wet meadows statewide, especially in the eastern and central regions.

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  Cyperaceae: Scirpus pallidus

  R. Neil Reese

  Scirpus pallidus is a perennial, herbaceous sedge that typically forms dense clumps or loose colonies. It grows from a robust, fibrous root system with well-developed, creeping rhizomes. Plants usually range from 50 to 120 cm tall. The stems (culms) are erect, slender, trigonous in cross-section, smooth, and soft, often pale green to green in color. Leaves are mostly basal and reduced, with long, sheathing leaf bases and narrow, grass-like blades; leaf blades can be up to 30 cm long up to 18 mm wide, typically flat or slightly channeled, smooth with a lighter green below and darker above. The sheath at the base is closed, smooth, and often tinged brown or reddish; the collar is indistinct, and the ligule is absent or represented by a short membrane. Flowering occurs from June to August. The inflorescence is a terminal, open to compact panicle (or sometimes head-like cluster), subtended by several leaf-like bracts, with many small spikelets, 2–7 cm across, with each spikelet 5–10 mm long and 2–3 mm wide. Each spikelet is subtended by a scale. The perianth consists of six reduced, bristle-like structures which may aid in seed dispersal. Stamens number three, with slender, pale filaments and small, light brown anthers. The pistil is single, with a short style and a three-branched stigma. Fruit is a small, lenticular achene, 1 mm long, brown at maturity, and matures from late July through September. Pale bulrush is native to South Dakota, found primarily in the eastern and central parts of the state in wet prairies, marshes, streambanks, and along the margins of shallow lakes and ponds.

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  Juncaceae: Juncus arcticus ssp. littoralis

  R. Neil Reese

  Juncus arcticus ssp. littoralis is a perennial, grass-like herbaceous rush that spreads vigorously through thick, creeping, horizontal, scaly dark-colored rhizomes. The plant typically grows to a mature height of 35 to 110 cm. Its unbranched stems are erect, solid, cylindrical, smooth to finely striate, 1 to 5 mm wide, and light green to dark green. The leaves are entirely basal and lack an expanded lamina or blade, rendering the leaf type a simple, vestigial structure wrapped around the stem base. These bladeless leaf sheaths are 2 to 15 cm long, varying from light tan to dark chestnut brown, and can be dull or shiny. The leaf sheaths feature fused margins that tightly clasp the stem, terminating in small, rounded, ear-like extensions (auricles) at the top. They lack a true distinct ligule or collar. Flowering occurs from June to August. The inflorescence is a lateral-appearing, branched cyme measuring 1 to 7 cm long and contains 5 to 50+ individual flowers. It appears to emerge from the side of the stem because the lowest involucral bract is green, cylindrical, and extends vertically up to 20 centimeters past the flowers, mimicking a seamless continuation of the stem. Individual flowers are small, bisexual, and radial with 6 separate perianth segments (tepals) arranged in two rows. The 3 outer sepals are free, lanceolate, 3.5 to 5 mm long, dark brown to purplish with green midribs, and sharply pointed. The 3 inner petals are similarly free, lanceolate, 3 to 4.5 mm long, and share the same dark brown coloration, but are distinguished by having wider, translucent membranous margins. The flowers have 6 stamens with very short filaments and prominent, linear, yellowish anthers. The single pistil consists of a superior, 3-chambered ovary bearing a short style and 3 long, feathery, protruding reddish-brown stigmas. The fruit is a small, 3-sided ovoid-oblong capsule measuring 3 to 4.5 mm long. It transitions from green to a glossy, dark chestnut brown or blackish color as it reaches maturity between July and October. Mountain rush is native to South Dakota. It is widely distributed across the state, with high concentrations throughout the central prairies and the western wet meadow complexes of the Black Hills region. It is primarily found in wetland habitats, including fens, marshes, wet meadows, stream margins, lake shores, roadside ditches, and low-lying alkali flats.

  Synonym: Juncus balticus

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  Juncaceae: Juncus torreyi

  R Neil Reese

  Juncus torreyi is a perennial herbaceous rush form loose colonies from a creeping rhizome, with stiffly erect, unbranched culms 30-80 cm tall. There are 1-3 basal leaves and 2-5 alternate leaves on the culms. Leaves are round in cross-section, often longer than the culms, with cross partitions at regular intervals. The sheath is open at the front with a pair of rounded lobes, 1-4 mm long. The inflorescence consist of 1-many flower heads in a tight cluster at the top of the stem. Each flower head is 1-1.5 cm in diameter, round, with up to 100 flowers. Each flower has 6 tepals, green to straw-colored, drying to dark brown, in 2 whorls, the outer set longer than the inner set. There are 6 stamens, a 3-parted style and the fruit is a capsule. Torrey’s rush blooms from June into October along lakes, streams in wet prairies and ditches throughout South Dakota.

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  Juncaginaceae: Triglochin maritima L.

  R. Neil Reese

  Triglochin maritima is a long-lived perennial, densely tufted, grass-like herbaceous monocot arising from a thick, stout, woody rhizome. The plant reaches a height of 30 to 100 cm at full maturity. Its flowering stems (scapes) are erect, unbranched, leafless, smooth, and stout. The leaves are entirely basal, simple, linear, alternate, and visually resemble thick blades of grass. They are bright green to deep green, measuring 8 to 30 cm long and about 2 to 5 mm wide. The leaf surfaces are fleshy, smooth, and glabrous; they feature a rounded or crescent-shaped cross-section that is flat or slightly channeled on the upper surface and rounded on the lower surface. The leaves transition directly into a wide, open, membranous sheathing base that clasps the stem. At the junction of the leaf sheath and blade, there is a prominent membranous ligule that measures 1.5 to 5 mm long with an entire or slightly notched/bilobed tip. Flowering occurs from May through August. The inflorescence is a dense, spikelike, terminal raceme measuring 10 to 40 cm in length, borne well above the foliage. The tiny, wind-pollinated flowers lack true distinct sepals and petals, featuring instead a perianth composed of 6 scale-like, yellowish green to purple-tinged segments arranged in two whorls of three. The outer three segments and the inner three segments are all free, concave, and roughly 2 mm long. The flower contains 6 stamens with short, nearly sessile filaments that are weakly fused to the base of the perianth segments; they carry small, greenish-yellow anthers. The compound pistil consists of 6 fully fertile, fused carpels with 6 sessile, feathery, papillate stigmas. The fruit is an oblong to almost cylindrical schizocarp, 3 to 8 mm long, which splits completely at maturity into 6 distinct, single-seeded mericarps. These fruits ripen from green to a dark brown color between July and October. Seaside arrowgrass is native to South Dakota, where it can be found locally within glaciated wetland regions, particularly in fens, wet alkaline lowlands, and brackish or saline marshes.

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  Poaceae: Alopecurus pratensis

  R. Neil Reese

  Alopecurus pratensis is a perennial grass in the Poaceae family. It forms dense tufts from a fibrous root system and can also spread via short rhizomes, sometimes forming loose sod. The stems (culms) are erect, simple, and unbranched, typically 40–110 cm in height and are smooth with little or no pubescence. Leaves are mostly basal, soft, flat, and linear, 3–10 mm wide and up to 35 cm long, with a rough texture and finely serrated margins; the ligule is long (up to 8 mm), membranous, and pointed, which is a distinguishing feature. Cauline leaves are fewer and shorter. Inflorescences appear from April to June and are dense, cylindrical spikes (5–12 cm long) that resemble a fox’s tail. Each bisexual spikelet is subtended by two glumes and contains a single floret with one lemma, a short palea, and a straight awn (5–8 mm) extending just beyond the glumes. The fruit is a caryopsis (grain), 2–3 mm long, narrow, and brown at maturity, ripening in early to mid-summer. Meadow foxtail is an introduced, cool-season grass in South Dakota, commonly found in moist meadows, pastures, ditches, and along streambanks, and is most abundant in the eastern part of the state and areas with higher soil moisture.

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  Poaceae: Andropogon gerardii

  R. Neil Reese

  Andropogon gerardii is a perennial warm season bunch grass. Mature plants have a well-developed fibrous root system 2-3 m deep, sending out short rhizomes, forming large dense bunches. The stems grow 1-3 m tall and become purplish toward the base. which grows 5 dm to 20 dm in height. These culms are solid and grooved on one side. The leaves have prominent midribs but are not keeled, many at the base of the plant and a few coming from the culm. The ligule is a fringed membrane 0.4-2.5 mm long. The inflorescence is a raceme of 3 (2-6) narrow racemes alternately arranged along the top of the stem, often looking like a turkey foot. Each raceme contains many pairs of spikelets, each pair having a stalked spikelet with another stalkless spikelet at the base of the stalk. The stalkless spikelet usually has a fertile, perfect floret with an awn, and the stalked spikelet is sterile or has a staminate flower that is awnless. This species is commonly found in pastures, along roadsides, and in open prairies. Big bluestem has green rust-red flowers that bloom from July to October.

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  Poaceae : Bouteloua curtipendula

  R. Neil Reese

  Bouteloua curtipendula is a rhizomatous perennial, warm season bunchgrass, with solid, erect culms arising in clumps. The leaf blades are rolled in the bud, but flat at maturity, 2-30 cm long and 2-6 mm wide. The upper surface is rough to the touch and often has hairs, especially along the margins. The lower surface is smooth. The ligule is fringed to eroded in appearance and less than 1 mm long. The inflorescence consist of 20-45 branches, 5-14 mm long, each with 3-8 spikelets, along the top 15 to 25 cm of the culm. The spikes often fall to one side of the stem, which gives the plant its name. Each spikelet is 4.5 to 10 mm long, with 2 glumes (bracts) and 2 florets, 1 sterile and 1 fertile with orange to brownish red anthers and a feathery 2 white stigmas. The fruit is a 1-seeded grain. Sideoats grama blooms from Jun into August on open grasslands and in woodland openings throughout South Dakota.

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  Poaceae : Bouteloua dactyloides

  R. Neil Reese

  Bouteloua dactyloides is a perennial, strongly stoloniferous, mat-forming grass, with solid culms that grow 3-20 cm in height. The leaves are rolled in the bud and flat at maturity, 1-10 cm long and up to 2 mm wide, smooth except with a few hairs in the collar region. The ligule is a fringe of hairs < 1 mm long, often flanked by long hairs. The plants are dioecious, the male inflorescences are on slender culms Having 2-5 one-sided branches, 7-13 mm long with 2 rows of spikelets each surrounded by 2 unequal bracts (glumes) one 1.4-3 mm the other < 5 mm long , surrounding 2 florets with 3 or fewer stamens. The male inflorescences are often retained into the fall. The female plants produce spikelets in 2-3 burr-like clusters subtended by modified foliage leaves, with 2-3, 1-flowered spikelets per burr. The fruit are grains that are retained in the burr. Buffalograss blooms from April into June in prairies predominantly on western South Dakota.

  Synonym: Buchloe dactyloides

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  Poaceae : Bouteloua gracilis

  R. Neil Reese

  Bouteloua gracilis is a mat-forming perennial grass, growing from short rhizomes, with solid culms reaching up to 50 cm in height. The leaf blades are C-shaped in the bud and flat to slightly rolled at maturity, 1-19 cm long and 0.5-2.5 mm wide. The leaf surfaces are often rough to the touch and may have hairs on one or both sides. The ligule is a short fringe of hairs less than 0.5 mm long. The inflorescence consists of 1-3 branches, 14-40 mm long bearing numerous spikelets. Each spikelet is surrounded by a pair of unequal glumes (bracts) with hairs along the midribs, one < 3.5 mm the other < 6mm long, containing 1 sterile and 1 fertile floret, each with a short awn. Fruit are single seeded grains. Blue grama blooms from June through August on dry prairies and waste grounds throughout South Dakota.

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  Poaceae : Bouteloua hirsuta

  R. Neil Reese

  Bouteloua hirsuta is a tufted perennial grass, with solid, erect and sometimes bent culms, which grow 10 cm to 45 cm in height. The leaves are basal and alternate on the culms, c-shaped in the bud and flat to rolled at maturity. The blades are 5-25 cm long and 1-3 mm wide, with thickened margins and long, white hairs with pimple-like bases on at the base of the blade, on the margins and occasionally on either or both surfaces. The leaf sheath is smooth to hairy, especially near the ligule and the ligule is a fringe of hairs < 0.5 mm long. The inflorescence has 1 (occasionally 2+) branch, 15-30 mm long, that has 20 to 50 spikelets arranged on one side of the rachis, tightly packed in 2 rows, with the tip of the rachis extending 5 to 10mm beyond the terminal spikelet. The spikelets each have 2 unequal bracts (glumes) with extended tips (awns) that are green to purple, one < 4 mm long and the other 5 to 6 mm long with hairs along the midrib, which enclose one fertile and usually one sterile floret. The fruit is a 1-seeded grain, oblong-elliptic, brown, 2.5 to 2.6 mm long. Hairy grama blooms from July into October in prairies and pastures in southern South Dakota.

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  Poaceae: Brachyelytrum erectum

  R. Neil Reese

  Brachyelytrum erectum is a perennial, tufted grass with a short, fibrous root system and sometimes creeping rhizomes, though it rarely forms dense colonies. The plant has upright to arching, slender stems (culms) that are typically unbranched, growing 40–100 cm tall. Leaf blades are alternate, thin, flat, and softly hairy, 10–30 cm long and 0.5–2 cm wide, tapering to a pointed tip, with margins that may be rough to the touch. The leaf sheath is open, and the ligule is a short fringe of hairs. The inflorescence is a narrow, nodding panicle (spike-like in appearance), 5–15 cm long, with few to several spikelets. Spikelets are one-flowered, about 1–1.5 cm long, with a long, straight or slightly bent awn extending from the lemma. The fruit is a small, brown, dry caryopsis (grain) about 3–5 mm long, maturing in late summer. Bearded Shorthusk is native to South Dakota, generally found in rich, moist to mesic deciduous woods, shaded slopes, and streambanks, especially in the eastern and central regions.

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  Poaceae: Bromus inermis

  R. Neil Reese

  Bromus inermis is a long-lived perennial, herbaceous cool-season grass equipped with an aggressive, deeply penetrating fibrous root system coupled with an extensive network of tough, creeping underground rhizomes that form a dense sod. The plant typically reaches a mature height of 60 to 120 cm. Its erect, unbranched, and robust stems (culms) are smooth and completely glabrous, though the nodes may occasionally feature fine, sparse hairs. Leaf insertion is alternate along the culm, bearing simple, flat, linear, and deep green to grayish-green leaf blades that measure 15 to 40 cm in length and 5 to 15 mm in width. The leaf surfaces are primarily smooth and glabrous on both upper and lower faces, though they uniquely exhibit a conspicuous, tactile, "M" or "W"-shaped crinkle or crimp situated near the middle of the blade. Structurally, the leaf sheaths are continuous and closed (fused) for most of their length—a defining characteristic of the genus—and are hairless or nearly so. The collar is a distinct, pale band, while the ligule is a short, truncate, membranous ring measuring 0.5 to 3 mm long with an entire to slightly lacerate margin. Flowering occurs from June through July, giving rise to an open, terminal panicle inflorescence that measures 10 to 20 cm in length. The panicle branches are initially erect and spreading but typically droop or nod slightly to one side at maturity. Each branch holds multi-flowered, elongated, cylindrical spikelets that span 20 to 40 mm long. Two unequal, unawned glumes occur at the base of each spikelet. The lower glume is single-nerved, 4 to 6 mm long, while the upper glume is three-nerved, 6 to 10 mm long; both are lanceolate, free, glabrous, and green with purplish or translucent margins. The lemma is oblong-lanceolate, 9 to 12 mm long, purplish-brown to green, unnotched or slightly notched at the apex, and notably lacks an awn (or bears a minute vestigial awn under 1 mm long). Inside each floret, the androecium contains 3 stamens with prominent, pale yellow to reddish purple anthers measuring 3.5 to 6 mm in length. The gynoecium consists of a single pistil with a superior, 1-celled ovary bearing 2 distinct, feather-like styles and stigmas projecting laterally during anthesis. The fruit is a specialized caryopsis (grain) that is flat, linear-oblong, dark brown to purplish-black, measures 6 to 8 mm long, and tightly adheres to the palea. The grains ripen to full maturity between July and August. Smooth brome is not native to South Dakota; it is an introduced species native to Europe and temperate Asia. Since its introduction, it has spread aggressively throughout the entire state of South Dakota. It is primarily found invading disturbed areas, degraded prairies, old pastures, roadside ditches, and fields where it readily outcompetes native vegetation.

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  Poaceae: Bromus tectorum

  R. Neil Reese

  Bromus tectorum is an annual grass with a fibrous root system that often penetrates deeply into the soil, reproducing solely by seed. The culms (stems) are slender, erect to ascending, and typically 20–70 cm tall, often loosely tufted and branching only at the base. The plant is densely covered in soft, fine hairs, giving it a downy texture throughout. Leaf blades are alternate, linear, 5–20 cm long and 2–5 mm wide, flat or loosely folded, and also softly hairy. Sheaths are open and hairy, with a membranous, notched ligule at the base of each blade. Flowering occurs in the late spring to early summer. The inflorescence is a loose, nodding panicle 7–20 cm long, often purplish at flowering, with slender, drooping branches. Spikelets are 1.5–3 cm long (excluding awns), each with 5–8 florets. Each floret has a lemma with a long, straight awn (10–15 mm) that becomes conspicuously sharp and barbed at maturity. The fruit is a slender, brown caryopsis (grain), maturing in early to mid-summer. Cheatgrass is introduced and invasive in South Dakota, rapidly colonizing disturbed ground, pastures, rangelands, roadsides, and open woods, found statewide but especially abundant in dry, open sites.

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  Poaceae: Cenchrus longispinus

  R Neil Reese

  Cenchrus longispinus is an annual grass with solid culms 20-60 cm tall. Multiple culms can be sprawling, ascending or erect, are smooth, often branching and mostly covered by the sheaths. The stem is often reddish at the base and light green above. The ligule is fringed with short, white hairs, 0.6-1.8 mm long. The sheath is contracted where the blade emerges, open at the front, and sometimes with a few long hairs at the constriction. The alternate leaves , 4-14 cm long, 3-7 mm wide, rough on the upper surface, mostly smooth on the lower, flat, folded lengthwise, or rolled up along the edges. The inflorescence consists of terminal and axillary spike-like clusters of burs, 2.5-10 cm long. Each bur has 30 or more spines of various sizes, the largest ones 3-5 mm long. There are with 2 or 3 spikelets per bur and 2 florets per spikelet, 1 fertile and the second staminate of sterile. The fruit are a single grain per spikelet that are retained within the bur. Sandbur blooms from July into September in disturbed ground throughout South Dakota.

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  Poaceae: Echinochloa muricata

  R. Neil Reese

  Echinochloa muricata is an annual grass growing from a fibrous root system. Stems are 30 to 100 cm in height, erect and robust, often branched near the top, usually smooth or slightly rough, with a round to slightly flattened cross-section. Leaves are alternate and linear-lanceolate, 10–30 cm long and 1–2 cm wide, with rough margins and a prominent midrib. The leaf sheath encloses the stem partially; the ligule is membranous, short, and translucent. Flowering occurs from mid to late summer (July–September). The inflorescence is a large, open, pyramidal to somewhat contracted panicle up to 20 cm long, composed of many spikelets. Each spikelet is flattened, lanceolate, about 3–6 mm long, green to purplish, bearing one to several florets. Spikelets have a scabrous (rough) surface covered with minute prickles (muricate texture), which gives the species its name. Each floret has three stamens and two feathery stigmas. The fruit is a small, oval caryopsis (grain), enclosed within a hardened lemma and palea, brown at maturity and 1.5–2 mm long, maturing in late summer. Rough barnyard grass is native to South Dakota, found in wetlands, ditches, floodplains, moist fields, and disturbed wet sites statewide, especially in eastern parts of the state.

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  Poaceae: Elymus canadensis

  R. Neil Reese

  Elymus canadensis is a perennial cool-season bunchgrass growing from a robust, fibrous root system forming clumps rather than sod. . Stems (culms) are sturdy, erect, rigid, and typically 60–150 cm tall, smooth to slightly rough. Leaves are alternate, flat, and linear, typically 10 to 30 centimeters long and 5 to 15 millimeters wide, with rough margins and a blunt or tapered tip and sheaths that tightly wrap the stem. Both basal and cauline leaves are present. The ligule is prominent, translucent, membranous, about 2 to 5 millimeters long, with a finely toothed or jagged margin. The inflorescence is a dense, spike-like raceme 10 to 30 centimeters long, composed of several spikelets arranged in two rows along the axis. Each spikelet is 10 to 15 millimeters long, containing 2–5 florets with awns 1–3 cm long. Flowers are bisexual, with three stamens with slender filaments and large anthers and a single pistil topped with two feathery stigmas The fruit is a caryopsis (grain), 5–7 mm long, brown at maturity, ripening in late summer. Canada wild rye is native to South Dakota, growing in prairies, open woodlands, roadsides, and disturbed sites statewide, with higher abundance in central and eastern regions.

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  Poaceae: Elymus repens

  R. Neil Reese

  Elymus repens is a perennial, cool-season grass that spreads aggressively via rhizomes, often forming dense mats. Stems (culms) are erect to arching, simple to sparingly branched, typically 30–120 cm tall, smooth or slightly roughened near the nodes. Leaves are alternate, flat, linear, typically 10 to 30 centimeters long and 5 to 12 millimeters wide, with rough margins, a pointed tip and sheathing bases. The ligule is membranous, about 2 to 4 millimeters long, with a jagged or irregular margin. The inflorescence is a slender, spike-like raceme 10 to 25 centimeters long, composed of numerous spikelets arranged in two rows along the axis. Spikelets are 10 to 18 millimeters long, each containing 2–4 florets with long awns often 3–6 cm in length giving the spikes a bristly look. Flowers are bisexual with three stamens and a single pistil crowned with two feathery stigmas. Fruits are caryopses (grains) about 4 to 7 millimeters long, enclosed by the lemma and palea. Seed maturation occurs from late summer to early fall. Quackgrass is native to Europe and parts of Asia. It is naturalized in South Dakota and considered an invasive weed, abundant in croplands, roadsides, disturbed soils, and pastures statewide.