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  Liliaceae : Allium textile

  R. Neil Reese

  Allium textile is a perennial herb coming from an underground egg-shaped bulb that is up to 2.5 cm long. This onion is shorter than the other common onions growing in South Dakota, often having multiple stems coming from a single bulb which grow from 10 to 30 cm in height. The stems are often curved or twisted in appearance. The plant has 1 or 2 flat grass-like leaves that are (2) 1-3 mm wide, alternately attached near the base, sheathing the stem, and may appear to be basal. Allium textile has numerous flowers arranged in a compact umbel and bloom from May to June.. The tepals are white to rarely pink in color, 5-7 mm long. The stamens are not exerted from the tepals as with the other common onions of the region. The fruit is a capsule. This species is commonly found throughout the state in mixed grass prairies, sagebrush steppes, meadows, open pine forests, and clearings.

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  Liliaceae : Calochortus nuttallii

  R. Neil Reese

  Calochortus nuttallii is a perennial herb growing from a membranous coated bulb, 14-44 cm in height. The 2-4, simple, alternate leaves are linear, 8-16 cm long and 1-2 mm wide, reduced in length toward the top. The inflorescence is a single terminal flower {occasionally 2-3), white with a yellow base, the outer whorl of tepals (sepals) are lanceolate, 20-33 mm long and 4-8 mm wide. The inner 3 tepals are obovate with a narrow base, 30-45 mm long and 27-38 mm wide, with a round gland surrounded by a fringed membrane covered with simple and/or branched hairs. The 6 stamens have filaments 5-8 mm long and anthers 5-10 mm long. The fruit is a linear-lanceolate, dehiscent capsule, 3-5 cm long. Sego lilies bloom in June and July on dry prairies and open woods in western South Dakota.

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  Liliaceae : Hypoxis hirsuta

  R. Neil Reese

  Hypoxis hirsute is a perennial herb growing from a rounded, membranous coated corm. There is a rosette of 3-6 basal, linear leaves, 5-26 cm long and 2-12 mm wide, green with scattered white hairs. The plants produce one to several slender flowering stems (scapes), up to 20 cm tall, each with a 2-14 flowers in a terminal umbel. The flowers have 6 yellow tepals, 6-14 mm long and 2-6.5 mm wide, with hairs on the outer surfaces. There are 6 stamens, the filaments 2-3 mm long and the anthers 2-4 mm long. The ovary is inferior and hairy. The fruit is a hairy, ovoid capsule. Yellow stargrass blooms from April into July on prairies and in open deciduous woodlands in eastern South Dakota.

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  Liliaceae : Maianthemum racemosum

  R. Neil Reese

  Maianthemum racemosum is a perennial herb from a whitish rhizome with simple, erect stems growing 35-80 cm tall. The simple, alternate, lanceolate to elliptical leaves are 2-ranked, 6-15 cm long and 2-7 cm wide. The leaves are sessile or with a short petiole, have a rounded bases, a pointed tips, and entire margins, with prominent veins running the length of the leaves. The inflorescence is a many-flowered panicle. The flowers have 6, white tepals, 1-4 mm long and 6 stamens that are longer than the tepals. The fruit is a green to red to purple berry, 4-6 mm in diameter. False Solomon’s Seal blooms from April into July in moist woodlands and thickets in the eastern and western border counties of South Dakota.

  Synonym: Smilacina racemosa

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  Liliaceae : Maianthemum stellatum

  R. Neil Reese

  Maianthemum stellatum is a perennial herb from a whitish rhizome with simple, erect stems growing 15-65 cm tall. The simple, alternate, lanceolate to oblong leaves are 2-ranked, 4-16 cm long and 1-4 cm wide. The leaves are sessile, folded, have pointed tips, and entire margins, with a prominent central vein. The inflorescence is a raceme, sessile or with a short peduncle. The flowers have 6, creamy white to greenish white tepals, 4-7 mm long and 6 stamens are 2-5 mm long, shorter than the perianth. The fruit is a berry, 7-9 mm in diameter, initially light green with blue stripes and turns dark blue purple as it ages. Starry false Solomon’s Seal blooms in May and June in moist to dry woodlands, along streams and rivers throughout much of South Dakota.

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  Liliaceae : Trillium cernuum

  R. Neil Reese

  Trillium cernuum is a perennial herb from a short rhizome, the stem 30-50 cm tall, topped with a whorl of 3 terminal leaves. The simple, leaves are rhombic-obovate, 6-12 cm long and wide, with a petiole-like base and usually have a sharp tip. The flowers hang beneath the leaves on peduncles 3-4 cm long. The 3 green sepals are broadly lanceolate, 1.5-2 cm long. The 3 white petals are oval to obovate and 1-3 cm long. The 6 stamens have anthers and filaments that are each 4-5 mm long. The fruit is a berry, about 3 cm in diameter, that starts out white and ripens to a deep red. Nodding trillium blooms in June and July in the moist deciduous woods along the coteau des prairies in eastern South Dakota.

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  Liliaceae : Uvularia grandiflora

  R. Neil Reese

  Uvularia grandiflora is a perennial herb growing from a rhizome and thickened fibrous roots, with simple to occasionally branched stems, 35-70 cm tall. The simple, alternate, ovate oblong to elliptic leaves are 6-12 cm long and 2-6 cm wide, smooth on top and hairy below. The leaf margins are entire and membranous. The solitary flowers are terminal and drooping. There are 6 yellow tepals that appear twisted, 2.5-4.5 cm long, the tips pointed, with 2mm diameter nectaries toward the base. The 6 stamens are shorter than the petals. The fruit is a 3-lobed capsule containing several rounded seeds. Large bellwort blooms in April and May in moist woodlands along the eastern edge of South Dakota.

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  Liliaceae : Zigadenus elegans

  R. Neil Reese

  Zigadenus elegans is a perennial herb from a deep, truncated, fibrous coated bulb, with stems growing 10-70 cm in height. The simple, alternate leaves are linear, 10-35 cm long and 2-10 mm wide, with roughened margins. The basal leaves are folded and the cauline leaves flat. The inflorescence is a raceme (rarely a panicle) with few to numerous flowers. The 6 greenish white tepals are oval to obovate, 6-8 mm long with a 2-lobed dark green gland toward the base. The 6 stamens arise from the base of the partially inferior ovary. The fruit is a capsule 15-20 mm long. Death camass blooms from June into August in the plains, prairies and open conifer forests in counties along the eastern and western edges of South Dakota.

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  Linaceae : Linum lewisii var. lewisii

  R. Neil Reese

  Linum lewisii var. lewisii is a perennial with stems branching at the base and growing 20 to 80 cm in height. The simple, linear to linear lanceolate leaves are 1-3 cm long, alternate above and crowded on the lower portions of the stem where they can appearing whorled. The leaf margins are entire and the apex is pointed. The inflorescence is a panicle with few branches and spreading pedicels. The 5 sepals are green and 3.5-5 mm long. The 5 petals are blue (occasionally white), 10-15 mm long, with the stamens opposite them. The fruit is an ovoid capsule, 5-7 mm long, that separates into 10 segments. Prairie flax blooms from May into August in prairies and on open wooded hillsides in the eastern and western border counties of South Dakota.

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  Loasaceae : Mentzelia decapetala

  R. Neil Reese

  Mentzelia decapetala is a coarse, erect, shrubby looking, biennial to weakly perennial herb growing up to 1 m tall. There are 1 to several stems that branched above, and the lower stems develop a whitish, exfoliating bark. The leaves are alternate, fleshy, lanceolate, 4-15 cm long, 1.5-4 cm wide, pinnatifid with wavy lobes, the lower leaves petiolate and the upper sessile. The flowers are solitary or in small clusters at the ends of branches. The 5 sepals are 1-5 cm long with pointed tips, and the 10 petals are white to cream colored, 5-7 cm long and 1-2 cm wide, oblanceolate to spatulate and often overlapping. There are numerous stamens that are shorter than the petals and form a yellow center in the opened flower. When open, the petals create a showy display, each flower up to 15 in diameter. The flowers open in late afternoon and close around midnight. The fruit is a cylindrical capsule 3-5 cm long and 1,5-2 cm wide with numerous, flattened, minutely winged seeds. Ten-petal blazingstar blooms from July into September along roadsides, and other disturbed places, including the Missouri River drainage, scattered throughout South Dakota.

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  Malvaceae : Sphaeralcea coccinea

  R. Neil Reese

  Sphaeralcea coccinea is a deep-rooted perennial herb with 1 or more decumbent to ascending stems growing from a woody caudex, reaching up to 50 cm in length, and usually covered with small hairs. The alternate, petiolate leaves are covered with hairs, irregularly divided 3-5 times, with the lobes divided again or merely toothed. The leaf blade’s overall outline is 1-6 cm long and about as wide or even wider, with the final narrow segments being oblong to oblanceolate. The inflorescence is a raceme, 2-11 cm long, and usually without subtending bracts. The flowers have short pedicels, a tubular calyx 3-10 mm long with 5 lobes that are equal to or longer than the tube. The 5 deep orange to brick red petals are 1-2 cm long and notched. There are numerous stamens, fused at the base, and 10 or more carpels, 3-3.5 mm tall, with stellate hairs at maturity. The fruit is a schizocarp. Scarlet globemallow blooms from April into August on dry prairies, plains and on hillsides in much of South Dakota.

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  Monotropaceae: Pterospora andromedea

  R. Neil Reese

  Pterospora andromedea is a non-photosynthetic, leafless, perennial, parasitic herb growing 20 to 60 cm tall from a thick, fleshy rootstock that forms a mycorrhizal association with certain pine species. The erect stem is reddish to brownish and covered with glandular hairs, branching near the top. Instead of true leaves, it bears scale-like bracts along the stem. The inflorescence is a dense raceme of nodding, urn-shaped flowers blooming from May through August. Each flower measures about 1.5 to 2.5 cm long, with five fused petals, 12 to 18 mm long, forming a pale cream to reddish bell-shaped corolla. The calyx consists of five small, persistent, triangular, greenish to reddish, lanceolate sepals, 3 to 5 mm long, beneath the corolla. Flowers have 10 stamens inserted on the corolla tube, with filaments alternating in length and the anthers are yellow. The style is slender, extending beyond the stamens, terminating in a bilobed stigma. Fruits are capsules, 8–12 mm long, maturing from August through September and contain numerous tiny seeds. Native to South Dakota, Pinedrops is found primarily in coniferous forests, especially under pine trees where its fungal host grows, mainly in the Black Hills and western regions of the state.

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  Nyctaginaceae: Mirabilis nyctaginea

  R. Neil Reese

  Mirabilis nyctaginea is a perennial herbaceous plant typically growing 30 to 90 cm tall. It has a thick, often tuberous root system that helps it survive dry conditions. The stems are erect or sprawling, branched, and covered with fine hairs. Leaves are opposite, ovate to broadly lanceolate, measuring about 4 to 12 cm long and 2 to 6 cm wide, with smooth or slightly wavy margins. The leaf surfaces are smooth to slightly hairy. Leaves are petiolate with slender petioles. The plant is named “four o’clock” because its flowers typically open late afternoon to evening and close by morning. The inflorescence consists of clusters of trumpet-shaped, tubular flowers that are usually cream, yellowish, or pinkish, blooming from summer to early fall (July–September). Each flower is about 2.5 to 4 cm long, with five fused petals forming a funnel shape, the lobes of the corolla are rounded and softly ruffled at the edges. Bracts subtend each flower cluster and are leaf-like, often with pointed tips. They measure 5-6 mm long at anthesis and grow to 1.5 to 3 cm long and 0.5 to 1.5 cm wide in fruit. The flowers are fragrant and attract moths for pollination. The fruit is a small, hard, three-lobed, one-seeded nutlet enclosed in a persistent, winged calyx (bracts). Wild four o’clock is native to South Dakota and commonly found in disturbed areas, roadsides, and open woodlands in much of the state, but is most often reported in central and eastern regions, where agricultural and roadside habitats provide ideal growing conditions.

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  Nymphaeaceae: Nuphar lutea

  R. Neil Reese

  Nuphar lutea is a perennial aquatic plant with stout, creeping rhizomes anchored in muddy substrates of freshwater ponds, lakes, and slow-moving streams. The floating leaves are orbicular to ovate, 10 to 25 cm long and 8 to 20 cm wide, with a heart-shaped base, thick and leathery with smooth margins and a smooth, glossy upper surface. The solitary flowers, borne on thick stalks rising above the water, have 4 to 6 broadly ovate sepals measuring 15 to 25 mm long, enclosing numerous bright yellow petals about 10 to 15 mm long and 3 to 5 mm wide, which are oblong to spatulate in shape and arranged in multiple layers. The flower contains 40 to 60 stamens with slender filaments and yellow anthers arranged in several concentric whorls around numerous free pistils. Each pistil has a short style and a small, rounded stigma. The fruit is an aggregate of achenes embedded in the spongy receptacle, maturing underwater into a berry-like structure, 3–6 cm in size, containing many small seeds released gradually as the fruits disintegrate. Yellow waterlily, as recognized by the USDA, is native to South Dakota, found in some natural and artificial wetlands, ponds, lakes, and slow-moving waters.

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  Onagraceae : Calylophus serrulatus

  R. Neil Reese

  Calylophus serrulatus is a perennial herb with few to many simple to branched, decumbent to erect stems, 5-80 cm long. The simple, alternate leaves are linear to lanceolate, 1-10 cm long and 1-12 mm wide, smooth to slightly hairy on top and generally hairy on the under surface. The blades are sessile to semipetiolate, the leaf tapering to the base and having a pointe tip, with margins that are entire to toothed. The 4-merous flowers are axillary in the upper parts of the stems. The sepals are 1.5-9 mm long and 2-6 mm wide, distinctly keeled, hairy below, with free tips 1-4 mm long. The 4 yellow petals are 5-20 mm long and about as wide. There are 2 series of stamens, one attached to the sepals and the other the petals, the former longer than the latter, and the stigma is ~2 mm wide in the center of the flower. The fruit is a capsule, 10-30 mm long and 1-3 mm wide. Yellow sundrops bloom from May into September on roadsides in rocky to sandy prairies and open woodlands in much of South Dakota.

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  Onagraceae : Chamerion angustifolium ssp. circumvagum

  R. Neil Reese

  Chamerion angustifolium ssp. circumvagum is a stout, erect perennial herb with simple to branched, red stems growing up to 3 m tall, that are smooth to occasionally having short, stiff hairs toward the top. This plant has an large root system, producing extensive colonies by forming shoots on lateral roots. The alternate leaves are lanceolate, with an acute tip, 2-20 cm long and 4-35 mm wide and arranged in a spiral. The leaves are sessile or nearly so, with a strong midvein and margins that are usually wavey. The inflorescence is a terminal many-flowered raceme. The slightly irregular flowers are drooping in the bud, the 4 spreading, green to purple sepals are lanceolate, 7-16 mm long and less than 3 mm wide. The 4 pink to magenta petals are obovate, tapering to a short claw, 10-20 mm long and 6-11 mm wide, usually with a notch. There are 8 slightly unequal stamens surrounding a pistil with a densely white haired ovary 8-18 mm long atop of a pedicel 4-12 mm long, with a white to purplish style, 10-20 mm long, with a ring of hairs at its base and topped by a 4-lobed stigma. The fruit is a capsule 4-10 cm long on a pedicel up to 2.5 cm long, containing may long-haired seeds. Fireweed blooms from June through September in open woodlands and disturbed areas, especially after fires in western South Dakota.

  Synonyms: Epilobium angustifolium, Chamaenerion angustifolium

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  Onagraceae: Epilobium ciliatum

  R Neil Reese

  Epilobium ciliatum is a perennial herb with erect, simple to branched stems, 5-120 cm in height, green, hairless on the lower portions of the stem and the upper stem with a covering of short hairs mixed with glandular hairs, often in lines running down from the leaves. The leaves are mostly opposite toward the base and alternate on the upper stem, the lower leaves are smooth, obovate with distinct petioles and broader than the upper lanceolate leaves that are nearly sessile and sparsely covered in short hairs mixed with glandular hairs, especially along the midvein. The blades are 3-12 cm long and 5-45 mm wide, blunt to pointed at the tip, and the margins have small widely spaced teeth. The flowers are single at the ends of stems and in the upper leaf axils, atop a short peduncle, < 12 mm long, followed by a slender ovary, about 25 mm long, that is slightly wider than the peduncle. The 4 small, greenish red sepals that cup the flower are 1.5-5 mm long. The sepals, peduncle and ovary are all variously covered in short hairs mixed with gland-tipped hairs, often in lines. The 4 petals are white to pink to rose-purple, notched and < 5 mm long. There are 8 unequal stamens surrounding a white, club-shaped style. The fruit is a long, slender capsule, 4-10 cm long, drying to brown then splitting lengthwise from the top down in 2 to 4 segments. The seeds are brown, 1-1.5 mm long with a tuft of long, white hairs. Fringed willowherb blooms from July into September in moist, often disturbed sites scattered throughout South Dakota.

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  Onagraceae : Oenothera biennis

  R. Neil Reese

  Oenothera biennis is a biennial herb with greenish, erect branching stems 50-200 cm tall, often covered with hairs. The first year plants form rosettes of petiolate leaves, oblanceolate to spatulate, 6-30 cm long, 1-7 cm wide, with an entire to wavey margin and pointed tips. The second year the stems elongate and the cauline leaves are alternate, lanceolate to oblanceolate, 1-10 cm long and 4-20 mm wide with wavey to sparsely toothed margins and pointed tips. The lower stem leaves petiolate, becoming reduced in size and sessile toward the top. The inflorescence is a terminal spike, sometimes with branches, the flowers subtended by hair covered bracts 1-3 cm long. The flower buds are erect and open near sunset. The slender, greenish yellow floral tube is is 2-5 cm in length, with a scattering of hairs. The 4 linear-lanceolate sepals are 1-2.5 cm long with free lobes 1-4 mm long. The 4 yellow obovate petals are 1-2.5 cm long, notched, and become reddish before wilting. There are 8 yellow stamens surrounding a style with a cross-shaped stigma in the center. The fruit is an ascending, hairy, cylindrical capsule, 1.5-3.5 cm long and 3-6 mm in diameter. Common evening primrose blooms From July into October along streams and lakeshores, open woodlands and waste places scattered throughout South Dakota.

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  Onagraceae : Oenothera caespitosa

  R. Neil Reese

  Oenothera caespitosa is a perennial, acaulescent, mound forming herb from a branching caudex. Mature plants are typically 15-25 cm high and up to ~60 cm wide, with lateral roots giving rise to new plants. The leaf blades are oblanceolate to nearly linear, 3-21 cm long, 1-5 cm wide, with a winged petiole that is often as long as the blade. The margins vary greatly from almost entire to pinnately lobed to having irregular teeth that are rounded to sharp. The leaf blades, veins and margins can be variously covered with hairs or with hairs lacking. The flowers are solitary in the leaf axils, open near sunset and have a sweet scent. The floral tube is 3-8 cm long, slender and flared toward the end, often reddish in color. The sepals are 2.5-3.5 cm long lanceolate with pointed tips. The white petals are heart-shaped, 2.5-5 cm long, changing to pink after pollination. The 8 stamens are unequal in length and about 2/3 the length of the petals. The style is about as long as the petals and has a 4-lobed stigma. The fruit is a hard, lumpy, elongated capsule, 2-5 cm long with a constricted end. Gumbo lily blooms from May into August on dry, rocky prairies, hillsides and open woodlands in western and central South Dakota.

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  Onagraceae: Oenothera serrulata

  R. Neil Reese

  Oenothera serrulata is a biennial or short-lived perennial herb growing from a deep taproot with an erect, 30 to 90 cm tall, branched stem often covered in fine hairs. The basal leaves are lanceolate to narrowly ovate, 5 to 15 cm long and 1 to 3 cm wide, with finely serrated (serrulate) margins, and short petioles. The stem leaves are smaller and more linear. Flowering occurs from late spring into mid-summer (May–July). The flowers are large and showy, born singly or in loose clusters on elongating stems, opening in the late afternoon or evening and lasting into the night. Each flower has four sepals, narrowly lanceolate and 10 to 15 mm long, which reflex as the flower opens. The corolla consists of four petals, bright yellow fading to orange with age, each 25 to 40 mm long and 10 to 15 mm wide, broadly obovate to spatulate in shape with a slightly notched apex. The flower contains eight stamens with slender filaments and conspicuous yellow anthers arranged around a single pistil. The ovary is superior with a slender style, about 15 to 20 mm long, terminating in a four-lobed stigma approximately 3 to 4 mm wide; the lobes are elongated and slightly papillose. The fruit is a slender capsule, 4 to 7 cm long, maturing in late summer, containing numerous small seeds. Serrate-leaved evening primrose is native to South Dakota, typically found in sandy or rocky soils of prairies, open woodlands, and disturbed sites across the central and western parts of the state.

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  Onagraceae : Oenothera suffrutescens

  R. Neil Reese

  Oenothera suffrutescens is a perennial herb, usually with several branched stems growing 20-100 cm tall, from a branching caudex and spreading underground stems the generate new plants and form large colonies. The simple, alternate leaves are almost sessile, linear to narrowly elliptic, 5-60 mm long and 1-7 mm wide with a pointed tip, the margins entire to having a few small teeth. The inflorescence is a spike-like raceme, 5-60 cm long on a peduncle that is 1-6 cm long. The zygomorphic flowers appear sessile, each subtended by a bract. The floral tube is 4-12 mm long, with 4 sepals 5-10 mm long and 4 clawed (narrowed) petals 3-9 mm long and 2-4 mm wide, that are initially white, then changing to red-orange or reddish brown. There are 8 stamens, the anthers red or yellow and a central pistil with a style 10-20 mm long topped with a 4-lobed stigma. The fruit is a capsule 4-9 mm long constricted at the base. This species is highly variable in habit, flower color, size and pubescence, with plants ranging from smooth to densely hairy. Scarlet guara blooms from May into August in dry prairies, open wooded hillsides and stream valleys throughout South Dakota.

  Synonym: Guara coccinea

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  Orchidaceae: Corallorhiza striata

  R Neil Reese

  Corallorhiza striata is a perennial saprophytic herb, lacking roots and growing from a much-branched rhizome, with erect stems 15-45 cm tall. The simple stems are succulent, yellow to red to purple to brown, wrapped with membranous bracts, 1-14 cm long. The inflorescence is a terminal raceme, 5-16 cm long with up to 35 flowers loosely arranged and subtended by bracts < 4 mm long. The flowers are nodding, yellow tinged with red to purple stripes. There are 3 narrow sepals, sometimes striped, 5-18 mm long, and 2-5 mm wide and 3, often purplish striped, petals the 2 lateral ones are about the same length as the sepals. The lower petal forms a broad, fleshy, reflexed bilobed lip, 3-16 mm long and 3-8 mm wide. The fruit is an elliptic capsule 1.2-2 cm long. Striped coralroot blooms in May and June in cool, coniferous woodlands in decaying litter in western South Dakota.

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  Orchidaceae: Platanthera dilatata

  R Neil Reese

  Platanthera dilatata is a perennial herb growing 15-70 cm tall. The mostly alternate, lanceolate leaves are cauline, 3-20 cm long and up to 3 cm wide with a pointed tip. the inflorescence is a loose to densely packed raceme, 5-25 cm long with 10-50 flowers, subtended by lanceolate floral bracts 5-40 mm long. The white flowers have 2 broad petal-like sepals that flare laterally, 4-8 mm long. Two lateral petals and an upper sepal form a hood, 4–6 mm long. The lower lip is narrower than the side sepals and initially curves up, touching the tip of the hood, and then flowing downward forming a sac-like to slender spur. The fruit is an ellipsoid capsule 8–15 mm long and 3-4 mm wide. White bog orchid is fairly rare in SD. It blooms in July in swampy forests and wooded bogs in and around Lawrence County in the State.

  Synonym: Habeneria dilatata

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  Oxalidaceae: Oxalis dillenii

  R. Neil Reese

  Oxalis dillenii is a small annual herbaceous plant growing 10 to 30 cm tall with slender, branching stems that are often slightly hairy. The trifoliate leaves are composed of three heart-shaped leaflets, each 1 to 2 cm long and 1 to 1.5 cm wide, with a distinct fold along the midrib and a bright green color. The flowers are borne singly or in small clusters on slender stalks above the foliage, blooming from May through October. Each flower has five green, lanceolate sepals about 4 to 6 mm long and 1.5 to 2 mm wide. The corolla consists of five bright yellow petals, each 8 to 12 mm long and 4 to 6 mm wide, obovate in shape with a rounded apex. The flower contains ten stamens with filaments of varying lengths and yellow anthers arranged around a superior ovary. The pistil has a single style approximately 5 to 7 mm long, terminating in a capitate (head-shaped) stigma about 1 to 1.5 mm wide. The fruit is a cylindrical capsule 10 to 15 mm long and 2 to 3 mm wide, developing after flowering from June through October; it dehisces explosively to release numerous small seeds. Southern Wood-sorrel is considered a native weed in South Dakota. It is difficult to distinguish from Oxalis stricta without a microscopic analysis of mature specimens. Oxalis dillenii has short, dense appressed hairs on the stems. The unbranched flower clusters typically have two flower buds, and the fruits of erect capsules are attached to bent or spreading stalks.

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  Oxalidaceae: Oxalis violacea

  Richard Neil Reese

  Oxalis violacea is a perennial herbaceous plant growing 15 to 40 cm tall from fibrous root system with small corms. The trifoliate leaves consist of three heart-shaped leaflets, each 1.5 to 3 cm long and 1.5 to 2.5 cm wide, with smooth margins and they often have a purplish tint on the underside. The leaves are petiolate with slender stalks 5 to 12 cm long. The flowers are borne singly on slender stalks above the foliage, blooming from April through June. Each flower has five green, lanceolate sepals about 6 to 8 mm long and 1.5 to 2.5 mm wide. The corolla consists of five petals, violet to lavender in color, each 10 to 15 mm long and 6 to 8 mm wide, obovate to broadly spatulate with a rounded apex. The flower contains ten stamens in two whorls with filaments of varying lengths and purple anthers arranged around a superior ovary. The pistil has a single style approximately 6 to 8 mm long, terminating in a capitate stigma about 1.5 to 2 mm wide. The fruit is a cylindrical capsule 12 to 18 mm long and 2 to 3 mm wide, developing after flowering from May through July; it dehisces explosively to release numerous small seeds. Violet wood-sorrel is native to South Dakota, commonly found in moist prairies, open woodlands, and along stream banks throughout the eastern and central parts of the state.