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  Aceraceae : Acer negundo

  R. Neil Reese

  Acer negundo is a perennial short-lived tree growing to about 25 to 35 meters. Leaves are opposite compound pinnate with three to seven leaflets. Leaflets are 5 to 10 centimeters long and three to seven centimeters wide. Flowers appear in the spring with staminate flowers that have 3-5 stamens, hang in clusters at the tips of branches and are often maroon in color. Pistillate flowers on drooping clusters of 6-12 flowers having 3-5 sepals and a 2-parted style. The fruit is a winged double samara. The trees are dioecious, with male and female flowers on separate trees.

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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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  Agavaceae : Yucca glauca

  R. Neil Reese

  Yucca glauca is an acaulescent, semi-woody perennial plant arising from a thick underground caudex, growing singly or in clumps. The green leaves are simple, waxy, flat to rolled 40-70 cm long and 0.5-1.5 cm wide, with margins that are greenish white and becoming fibrous. The inflorescence is a raceme on a long stalk 1-1.5 m tall, usually simple but occasionally branched. The flowers are globose to campanulate with 6 thick perianth segments that look similar, greenish white and tinged with purple, 3.5-5.5 cm long and 2.3-3 cm wide. The stamens are 1-2 cm long and the 3-parted pistil has styles 8-12 mm long atop ovaries that are 3-3.5 cm in length. The fruit is a capsule 4.5-6 cm long and contains numerous seeds that are 7-10 mm in diameter. Yucca blooms in May, June and July on plains, prairies and occasionally in open coniferous forests in the western and southern portions of South Dakota.

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  Alismataceae : Sagittaria cuneata

  R. Neil Reese

  Sagittaria cuneata is a perennial aquatic herb growing from a white corm. The leaves are variable in shape and can be submerged, floating or emersed from the water, with many of them being arrow shaped. The submerged parts of the plant look different from those growing above the surface or on land. Petioles of emersed leaves are 3-50 cm long while those of floating leaves may reach 100 cm. The blades of the leaves are 5-20 cm long with two smaller, pointed lobes opposite the larger tip that makes up half or more of the leaf length. The plant is monoecious, bearing both male and female flowers. The inflorescence rises above the surface of the water on a triangular peduncle 10–50 cm long; a raceme made up of 2–10 whorls of flowers, the lowest node bearing female flowers and upper ones bearing male flowers. Each flower is up to 2.5 mm in diameter with 3 recurved sepal 4-9 mm long and white petals that are about twice the length of the sepals. The fruit are achenes attached to fruiting heads that are 0.8 to 1.5 cm wide. Arrowhead blooms from June through September in ponds, lake shores and streamside throughout South Dakota.

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  Anacardiaceae : Rhus glabra

  R. Neil Reese

  Rhus glabra is a shrub to small tree with a spreading, open habit, growing from 3 to 5 m tall and spreading by root suckers to form dense thickets. The young stems and branches are hairless or nearly so and waxy. The bark on older wood is smooth and grey to brown. The compound pinnate leaves are alternate, 30-50 cm long with very short petioles (4-7 mm long). Each leaf has 11–31 oppositely paired leaflets, each leaflet lanceolate to ovate-lanceolate, 7-9 cm long, with a toothed margin. The leaves turn scarlet in the fall. The inflorescence is a dense terminal panicle 10-20 cm long, with numerous tiny green flowers. The fruit are compressed crimson drupes 3.5-4.5 mm in diameter, and they remain throughout the winter. The seeds are yellowish, smooth and about 3 mm long. Smooth sumac bloom in May and June and the fruit ripen in August and September. They are common in open woodlands in thickets, prairies, and roadsides throughout South Dakota.

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  Anacardiaceae: Rhus trilobata

  R. Neil Reese

  Rhus trilobata is a deciduous shrub, upright, ascending or spreading, 2-3 m tall, branches covered with short hairs when young. The compound leaves are alternate, trifoliate, petiolate, the leaflets are each elliptic to obovate, 1.5-2.5 cm long, with a wedge-shaped base and a few rounded teeth. The terminal leaflet is often 3-lobed. Leaves and branches have an strong unpleasant odor. The inflorescence is a terminal compound spike of dioecious catkins (0.5-2 cm) with 5-merous flowers that have greenish sepals, united at the base and greenish white to creamy yellow petals. Fruit is a subglobose drupe, orange-red, 5-7 mm in diameter wide with red glandular and translucent hairs. Skunkbrush sumac flowers in the spring (April – June) with leaves and flowers often appearing at the same time. This shrub is found on wooded hillsides, in canyons and prairie ravines mostly on the western side of South Dakota.

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  Anacardiaceae: Rhus typhina

  R Neil Reese

  Rhus typhina is a shrub to small tree with a spreading, open habit, growing from 3 to 5 m tall and spreading by root suckers to form dense thickets. The young stems, leaf petioles and buds are densely covered with rust colored hairs. The bark on older wood is smooth and grey to brown. The compound pinnate leaves are alternate, 25-55 cm long with very short petioles (4-7 mm long). Each leaf has 9–31 oppositely paired leaflets, each leaflet lanceolate to ovate-lanceolate, 6–11 cm long, with a toothed margin. The leaves turn scarlet in the fall. The inflorescence is a dense terminal panicle 10-20 cm long, with numerous tiny green flowers. The fruit are compressed crimson drupes 3.5-4.5 mm in diameter with knobby hairs on much of the surface. The fruit remain on the plants throughout the winter. The seeds are yellowish, smooth and about 3 mm long. Staghorn sumac bloom in May and June and the fruit ripen in August and September. They are common in open woodlands in thickets, prairies, and roadsides throughout South Dakota.

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  Anacardiaceae: Toxicodendron rydbergii

  R Neil Reese

  Toxicodendron rydbergii is a perennial shrub or subshrub with simple, unbranched stems 0.3-2 m in height and growing from branched subterranean stolons that often form thickets. Leaves are compound ternate, often drooping, each group of 3 at the end of a long stalk alternately attached to the woody main stem. Leaflets are up to 16 cm long and 11 cm wide, the center leaflet ovate to rhomboid, pointed at the tip and rounded or tapering at the base with toothed margins. The 2 lateral leaflets sessile or with short petioles and asymmetrical in shape, toothless or having a few large teeth, sometimes just on one side. The upper leaf surface is hairless and shiny, becoming dull with age; the underside is lighter in color with a few hairs along the midvein. Flowers are in small, paniculate clusters that arise from the leaf axils. Each small flower 1-3 mm across, has 5 sepals that are fused and green below and cream colored and free above. The 5 petals are cream colored with purplish veins and yellow stamens are usually visible. The fruit is a whit to yellowish globose drupe 4-7 mm in diameter that often persist into the next year. Poison ivy blooms in May and June and sometimes again later in the summer. Plants are found on prairie hillsides, stream banks, flood plains, roadsides and open woodlands throughout South Dakota.

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  Apiaceae: Cicuta maculata

  R Neil Reese

  Cicuta maculata is a rhizomatous perennial herb with a hollow erect stem that can reach a height of 2 meters. The base of the stem is swollen, containing several chambers separated by well-developed transverse partitions, and usually mottled with purple blotches. The alternate compound bi to tripinnate leaves may be up to 40 cm long and are made up of lance-shaped, pointed, serrated leaflets. Each shiny green leaflet is 2 to 10 cm long. The inflorescences of loose compound umbels are attached to terminal and lateral branches on peduncles that exceed the leaves. The white flowers are similar in appearance to other species in the carrot family. The fruit is an oval, flattened 3-4 mm schizocarp that turns tan-brown when mature. Water hemlock flowers from July through September in wet meadows, roadside ditches, pond margins, open marshes, and freshwater swamps throughout South Dakota.

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  Apiaceae : Daucus carota

  R. Neil Reese

  Daucus carota is an introduced, somewhat variable, biennial herb with slender to course solitary stems that are usually branched and between 30 and 120 cm tall. The stems can be smooth to roughly hairy. The alternate, compound leaves are tripinnate, finely divided with an overall triangular shape and 5–15 cm long. The ultimate divisions are linear to lanceolate, 2-12 mm long. The inflorescence is a compound umbel on a long (7-50 cm) peduncle with the umbellets attached by unequal rays 3-7.5 cm long. The flowers are small and dull white and usually have a pinkish to purple flower in the center of each of the umbellets. As the seeds develop, the umbel curls up at the edges, becoming more congested, with a concave surface. The fruits are small schizocarps 3-4 mm long and 2 mm wide and bristly. The dried umbels detach from the plant and become tumbleweeds. Queen Anne’s lace blooms from late April through June along roadsides and in waste places in South Dakota.

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  Apiaceae : Heracleum maximum

  R. Neil Reese

  Heracleum maximum is a tall perennial herb reaching heights of 3 m, with hollow stems that are densely hairy , erect, with few to many branches. The lower compound leaves are ternate and softly hairy, with fine sharp teeth along the margins, very large, 20-50 cm long and equally as wide, becoming smaller as they ascend the stem. The leaflets are ovate 15-40 cm long and 10-35 cm wide, cordate with petioles 10-40 cm long. The end leaflet is largest and lobed in 3 parts; each lobe may be further divided. Leaf attachment is alternate, and the petioles clasping and sheathed. The inflorescence is a compound umbel that can reach 30 cm in diameter, flat-topped or rounded, composed of small white flowers. Individual flowers are about 6mm across with 5 white petals that are notched at the tip, the outer flowers being much larger than the inner ones. There are 5 white tipped stamens. A plant may have few to many flower clusters growing from the tips of branching stems and arising from the upper leaf axils. The fruit are schizocarps 8-12 mm long and 6-9 mm wide, strongly flattened dorsally. Cow parsnip flowers in May, June and July in moist woods, along streams and in thickets in both eastern and western South Dakota.

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  Apiaceae : Lomatium foeniculaceum

  R. Neil Reese

  Lomatium foeniculaceum is a perennial herb growing from a thickened or swollen taproot, either acaulescent or with a short stem. The alternate, pinnately compound leaves have blades up to 30 cm long and are intricately divided into many small, narrow linear segments 1-7mm long and 1 mm wide. The petioles are 3-15 cm long with a surrounding purplish sheath to about the middle. The inflorescence is a loose cluster of compound umbels on peduncles up to 30 cm long that exceed the leaves. The tiny flowers are yellow, and the ovaries are hairy. The fruit are oblong schizocarps 5-12 mm long and 4-8 mm wide. Desert biscuitroot blooms from march to June on rocky prairie hilltops, slopes and open dry prairies, mainly in western and central South Dakota.

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  Apiaceae : Lomatium macrocarpum

  R. Neil Reese

  Lomatium macrocarpum is a highly variable spreading or erect perennial herb growing from an elongated swollen taproot. The flowering stems are often branched, growing 20 to 50 cm tall. The alternate compound ternately pinnate leaves are clustered near the plant base. The hairy, gray-green leaves grow to about 24 cm in length with the ultimate divisions being oblong to linear and about 8 mm long by 2 mm wide. The inflorescences are compound umbels on 1-several spreading or ascending peduncles 10-20 cm long, and 2-8 mm wide, with white to purplish white to yellowish flowers. The fruit are 9-20 mm long schizocarps that are 2-8 mm wide. Big seed biscuitroot blooms in May and June on rocky hills and prairies and clay flats in western South Dakota.

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  Apiaceae : Osmorhiza longistylis

  R. Neil Reese

  Osmorhiza longistylis is a perennial from fleshy roots that are up to 1 cm thick. Stems grow to 1 m tall and can be smooth to densely covered with short hairs. The compound leaves are bi or triternate pinnate. The leaflet blades are ovate to oblong, 3-10 cm by 1-5 cm, the margins have small teeth to larger teeth to pinnate lobes toward the base and are covered with few to a many short hairs. The petioles are long (5-16 cm) and smooth to hairy. The inflorescence is a group of loose umbels both terminal and in the axils of the upper leaves. The umbels are attached by a 5-13 cm peduncle. Each umbel has about 5 umbellets, each umbellet has 8-16 tiny flowers. The flowers have 5 white petals, 5 white-tipped stamens, and 2 white styles which exceed the length of the petals. The fruit is a schizocarp 18-20 mm long. Long-styled sweet-cicely blooms from late April to June in woods thickets and along stream banks in eastern and western South Dakota.

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  Apiaceae: Perideridia gairdneri

  R Neil Reese

  Perideridia gairdneri is a slender, erect perennial herb with tuberous roots, the solitary stem growing from 30-80 cm tall. The alternate cauline leaves are petiolate. The blades are compound pinnate or bipinnate, with the ultimate leaflets linear to filiform, 4–12 cm long and often withered at the time of flowering. The inflorescence consists of 1-several compound umbels, the peduncle 3–10 cm long, rays 1–5 cm long; and with involucral linear bracts 1–4 mm long or absent. The flowers are white with conspicuous sepals. The fruit are nearly round schizocarps, 2-3 mm in diameter. Yampah blooms from July through August in moist meadows and woodlands in western South Dakota.

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  Apiaceae : Zizia aptera

  R. Neil Reese

  Zizia aptera is a perennial herb, erect with simple or branching stems which grow from a fleshy root and attain 30 to 70 cm in height. The basal leaves are chordate, simple 4-7 cm long and 3-5 cm wide, with petioles 5-10 cm long, with toothed margins. The cauline leaves are alternate, ternately divided, the divisions with margins having small teeth and often lobed. The inflorescences are loose compound umbels 5-7 cm across, attached to a long peduncle (6-10 cm) each with 7 to 15 umbellets attached by unequal pedicels (1-3 cm long) to terminal umbels of 12-18 flowers. Each tiny (< 3 mm) flower has 5 petals that remain nearly closed. The fruit is an oblong schizocarp ~ 3 mm long. Heartleaf Alexanders bloom from late April to July on moist meadows, prairies and open wooded hillsides.

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  Apiaceae : Zizia aurea

  R. Neil Reese

  Zizia aurea is a perennial herb, erect with simple or branching stems which grow from a fleshy root and attain 30 to 100 cm in height. The basal leaves are ovate, compound 6-10 cm long, bipinnate or the middle leaflet pinnately cleft. The leaflets are ovate to lanceolate, 2-5 cm wide and 1-3 cm wide, and finely toothed. The petioles are 10-15 cm long. The cauline leaves are alternate, are similar to the basal leaves, ternate or irregularly compound. The inflorescences are loose compound umbels 5-8 cm across, attached to a long peduncle (5-15 cm) each with 7 to 15 umbellets attached by unequal pedicels (1-4 cm long) to terminal umbels of 10-15 flowers. Each tiny (< 3 mm) flower has 5 petals that remain nearly closed. The fruit is an oblong schizocarp 3-4 mm long and 1.5-2 mm wide. Golden Alexanders bloom from May to July in low prairies, on the margins of ponds, ditches, and in open woodlands.

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  Apocynaceae : Apocynum androsaemifolium

  R Neil Reese

  Apocynum androsaemifolium is a perennial herb, somewhat woody dichotomously branched stems coming from rhizomes, ascending to erect and growing from 15-90 cm tall. They are smooth, light green to red in color. The leaves are simple, opposite usually with entire margins. The leaves generally droop but can be horizontal, having short petioles and are ovate to elliptical in shape, 1-9 cm long and 0.5-5 cm wide. Inflorescences are generally terminal (with some axial) open cymes. The flowers are drooping to somewhat erect. The 5-merous calyx is fused with lobes 1-3 mm long. The corolla is whitish-pink to pink with pink veins internally, broadly campanulate, 5.5-8.8 mm long and 4-8 mm wide, with lobes that are up to half the length of the tube. The fruit is a pendulous, usually straight follicle, 6-14 cm long. Spreading dogbane blooms from June to September, the seeds (2-4 mm long) emerge from the follicles in late summer and fall. They are covered in white hairs that are ~ 2 cm long. Plants can be found in prairies, at the edge of woodlands and around lakes and streams in both east and west river in South Dakota.

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  Apocynaceae : Apocynum cannabinum

  R Neil Reese

  Apocynum cannabinum is a perennial herb with branched stems coming from rhizomes, erect to ascending and growing from 0.6-2 m tall. Green to lightly red stems are alternate to opposite in orientation. The leaves are simple, opposite, ascending to erect with entire margins, sessile below and with short petioles above. The blades oblong to lanceolate, 2-14 cm long and 0.3-5 cm wide. Inflorescences are generally dense terminal cymes; the flowers erect to slightly drooping. The calyx is fused with lobes 1.2-3 mm long. The corolla is white to yellowish green, narrowly campanulate to urceolate, 2.6-4.7 mm long and 1.5-3 mm wide, with lobes that are less than half the length of the tube. The fruit are divergent to pendulous, straight to curved follicles, 7-22 cm long. Indian hemp blooms from May to September, the seeds (3-6 mm long) emerge from the follicles in late summer and fall. They are covered in white hairs that are 1.6-3 cm long. Plants can be found in prairies, roadsides, wooded waterways and sparsely wooded slopes in both east and west river in South Dakota.

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  Araliaceae : Aralia nudicaulis

  R Neil Reese

  Aralia nudicaulis is an aromatic acaulescent perennial herb With leaves and peduncles arising from long rhizomes. The compound leaves are usually solitary, erect and ternate with each division divided into 3-5 segments. The leaves are attached to petioles up to 50 cm long and the leaflets are lace-elliptic to obovate5-13 cm long acuminate with finely serrate margins. The peduncles are usually solitary, 5-13 cm long with 2-6 umbels. The 5 sepals are les than 1 mm long and the green to white petals are 1-2 mm long. The fruit are purplish black drupes 6-10 mm in diameter. Wild sarsaparilla blooms from May to July in woods in both east and west river South Dakota.

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  Araliaceae : Aralia racemosa

  R. Neil Reese

  Aralia racemosa is a perennial herb with a somewhat wood base, the stems purplish to spotted, 1-2 m in height. The alternate, compound pinnate leaves have 3-7 leaflets, up to 20 cm long and 15 cm wide, the leaflets varying in size on the same leaf, each with a saw-toothed margin. The inflorescence consists of terminal and axillary panicles of umbels, 4-40 cm long. The flowers have 5 tiny sepals (<1mm), 5 white petals, 1mm long, and 5 stamens. The fruit is a berry-like drupe, red to black in color, 5-6 mm in diameter. Spikenard flowers in July in wooded ravines and hillsides along the eastern edge of South Dakota.

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  Araliaceae : Arisaema triphyllum

  R. Neil Reese

  Arisaema triphyllum is a perennial herb, which grows from a corm, reaching 50 to 6 0 cm in height. Jack-in-the-pulpit is commonly found in moist to intermittently dry deciduous woods. The leaves are palmately divided into 3 leaflets, each ovate to elliptic and 6-22 cm long by 5-15 cm wide. The underside of the leaf is lighter than the upper side. The inflorescence is a spadix that is concealed by the spathe. The plants are monoecious with the pistillate flowers basal and staminate flowers above, on a spadix that is 5-8 cm long. The inner surface of the hood is purple to brownish red with yellow linear veins. The plants bloom from May to June. The fruit are fleshy red berries 5-7 mm long that become visible as the spathe dies back.

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  Aristolochiaceae : Asarum canadense

  R. Neil Reese

  Asarum canadense is a creeping perennial herb growing from shallow aromatic rhizomes. The leaves are simple, paired, basal, erect, long petioled, growing to about 20 cm tall and covered with a soft pubescence. The leaf blades are 4-15 cm wide, heart-shaped at the base and have an overall kidney shape with entire margins. A solitary flower is attached between the bases of the pair of leaves laying on the ground and hidden by the leaves. The petiole is 1-3 cm long and pubescent. The flower is regular, 1-2 cm wide with 3 spreading to reflexed brownish-purple, 1.5 cm long, sepals that are fused to the ovary. There are 12 stamens, and the ovary has 6 locules. The fruit is a dehiscent many seeded capsule. The sepals remain attached as the capsule matures. Wild ginger blooms from late April to June in the moist deciduous forests of the Coteau des Prairies in eastern South Dakota.

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  Asclepiadaceae: Asclepias incarnata

  R. Neil Reese

  Asclepias incarnata is a mostly solitary stemmed, upright, tall plant (70 to 200 cm) growing from a stout base and containing milky white sap. Usually, its stems have many branches toward the top. All portions of the plant contain a white milky juice. The mostly oppositely simple leaves are 5 to 15 cm long and 1 to 3 cm wide, ascending to spreading, narrow and lance-shaped, with the ends tapering to a sharp point and the margins entire. They are attached to the stem by a short petiole, 3-17 mm long. The inflorescences are terminal to the stem and branches, contain 10-40 flowers each attached by a short pedicel (10-17 mm) connected to a 1-7 cm peduncle. Flowers are 9-11 mm tall with 5-merous calyx has green to purple lobes 1.3-2.3 mm long. The petals are bright pink to rarely white, reflexed 5-6 mm long. The stamens and pistil are pink to white and fused, 1.2-1.8 mm tall and 1-1.5 mm wide. The fruit is an erect follicle 5-8 cm long. The seeds are broadly ovate 6-9 mm long and are covered with long white hairs. Swamp milkweed blooms from June through September and is commonly found in marshes, along banks of lakes, ponds and other waterways throughout South Dakota.

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  Asclepiadaceae : Asclepias pumila

  R. Neil Reese

  Asclepias pumila is a perennial herb with milky white sap, which grows from a taproot or slender rhizome with 1 to several stems arising from a branched base and reaching 8 cm to 30 cm in height. The leaves are simple, alternate in a tight spiral and often whorled near the base of the stem. The blade is narrow 1.5-6 cm long and about 1 mm wide, erect to spreading, lacks a petiole and the margin is entire. There are 1 to many inflorescences in the axils of the upper leaves, each with 4-20 flowers in an umbellate cyme. The flowers are 5-8 mm long, the calyx green to purple with 5 lobes. The corolla is white to pink tinged or sometimes a yellow green, reflexed and 2.8-4.2 mm long. The fruit are follicles that are erect, narrow cylinders 4-6 cm long and 6-8 mm wide. The seeds are ovate 4-6 mm long with long white hairs that turn brown with age. As with other milkweeds the stamens and pistils are fused, greenish-white and 0.6 to1.1 mm tall. Plains milkweed blooms from July to September in prairies and along hillsides throughout South Dakota.