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  Fabaceae : Glycyrrhiza lepidota

  R. Neil Reese

  Glycyrrhiza lepidota is a perennial herb arising from deep, woody, aromatic roots with multiple, erect stems, which grow 30-120 cm in height and are typically dotted with glands. The leaves are alternate, with petioles 5-50 mm long and stipules 3-7 mm long. The blades are compound odd-pinnate with oblong to lanceolate leaflets, 2-7 cm long with glandular dots, in groups of 7 to 21. The inflorescences are axial, dense, spike-like racemes of numerous flowers, with peduncles 1–6 cm long. The flowers have tubular-campanulate green calyx tubes that are 2-2.5 mm long, with teeth 2.5–3 mm long, the tube and teeth both having stalked glands. The papilionaceous corollas have white to yellowish white petals, the banner moderately erect, 10-14 mm long, keel and wings 8-12 mm long. There are 9 united stamens and 1 separate stamen. The fruit is an ellipsoid legume, 1–2 cm long going from green to orangish-brown with age and covered with hooked bristles 2–3 mm long. The fruit remain through the winter. American licorice blooms from July into September in prairie ravines, along streams and lakeshores and in other moist areas throughout South Dakota.

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  Fabaceae: Gymnocladus dioicus

  R Neil Reese

  Gymnocladus dioicus is a large, deciduous, perennial tree with rough bark and growing to 23 m tall. The young twigs are brown, hairless with light brown to orange lenticels. The large leaves are alternate, bipinnate, 30-90 cm long, 30-60 cm wide, with each leaf having 3-7 pairs of pinnae (branches), the branches up to 10 cm long and having 4-7 pairs of leaflets on each branch. The leaflets are 4-7 cm long, 2-3 cm wide, rounded at the base, pointed at the tip with entire margins. The inflorescence consists of terminal racemes or panicles, 5-30 cm long. the flowers have a tubular-obconic hypanthium 6-10 mm long, with 5 oblong sepals, 3-5 petals 4-5 mm long, 10 stamens with those opposite the petals slightly longer than those opposite the sepals. The trees generally produce either male or female flowers,but usually also produce some perfect flowers.The fruit is a flattened, oblong, indehiscent legume 5-15cm long and 3-5 cm wide, containing dark seeds, 15-20 mm in diameter. The fruit is green in the summer and turns purplish-brown as it dries. Kentucky coffee blooms in May and June in woodlands along streams and on open hillsides in southeastern South Dakota. This species has been planted in windbreaks and urban landscapes throughout SD and can be found in many regions as an introduced species.

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  Fabaceae: Mimosa nuttallii

  R. Neil Reese

  Mimosa nuttallii is a sprawling perennial herb with stems that grow up to 1 m long, covered with small prickles, 0.5-2 mm long. The alternate leaves are bipinnate leaf blades are divided into four to nine pairs (pinnae), and each of these have 8–15 pairs of leaflets, 3-9 mm long with a prominent midrib visible on the upper pairs and stipules 4-6 mm long. The leaves exhibit nyctinastic movement, folding up quickly when touched. The inflorescence consists of axillary, many-flowered heads, with peduncles 3-9 cm long. The pink to lavender flowers are sessile, with a minute calyx. The 5 united petals form a narrow tube about 4 mm long and lobes of about 1 mm, with 8-12 stamens inside. The fruit is a legume, 3-12 cm long and covered with prickles and explodes upon drying expelling the seeds. Nuttall’s sensitive briar blooms from April into September on prairies, in ravines and in open woodlands in central South Dakota.

  Synonym: Schrankia nutallii

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  Fabaceae : Oxytropis lambertii

  R. Neil Reese

  Oxytropis lambertii is an acaulescent perennial herb growing from a branching caudex, forming clumps of leaves that appear silvery due to a covering of short stiff and ax-shaped hairs. The leaves are up to 15 cm long with 7 to 19 linear-lanceolate leaflets, 5-40 mm long and 1-6 mm wide, with membranous, hairy stipules 7–24 mm long and having sharply pointed tips. Inflorescences develop on multiple, silvery-haired flowering stems (scapes), 10–30 cm long including the peduncle, each with 6 to 25 flowers per raceme. The calyx has a dense white covering of hairs, the sepals forming a tube that is 6-7 mm long with teeth 1.5-3 mm long. The papilionaceous flowers have red to blue to purple petals, the banner 15–25 mm long, the wings 12-20 mm long and the keel 13-19 mm long. The fruit is an silvery-haired, erect, sessile leathery or woody legume, 1–2 cm long, including the long beak. Purple locoweed blooms from May into August on prairies, plains, river bluffs and hillsides in much of South Dakota.

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  Fabaceae : Oxytropis sericea

  R. Neil Reese

  Oxytropis sericea is an acaulescent perennial herb growing from a much-branched caudex, forming mounds of silky-haired leaves. The leaves are 4-30 cm long with 11 to 25 lanceolate to narrowly ovate leaflets, 5–40 mm long and 2-10 mm wide. The petioles are 1-15 cm long with membranous, hairy stipules, 8–22 mm long. Inflorescences are terminal racemes of 6 to 30 flowers atop of erect to ascending scapes (flowering stems), 5–30 cm long, including the peduncle. The calyx is covered in white and/or black hairs, and forms a tubular-campanulate tube, 8-12 mm long with unequal teeth 2-5 mm long. The papilionaceous corolla is white to yellowish white; the banner 16–25 mm long and deeply lobed, the wings 15-20 mm long, and the keel is 12-17 mm long with a small appendage at the distal end. The fruit are sessile, erect, oblong legumes, 15–25 mm long, with a short beak and having a few short stiff hairs to a silky covering of hair. White locoweed blooms from April into June in rocky prairies, hillsides, open woods and valleys in southwestern South Dakota.

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  Fabaceae : Pediomelum argophyllum

  R. Neil Reese

  Pediomelum argophyllum is a perennial herb with multiple, erect to ascending, widely branching stems, 20-80 cm in height, growing from a subterranean caudex that forms colonies. The stems are usually covered in silvery hairs. The alternate leaves are palmately compound with 3 to 5 leaflets with 1-5 cm long petioles. The leaflets are 1–4 cm long, with entire margins, and covered with dense, shiny hairs. The inflorescence consists of axillary spikes, 2–9 cm long including the peduncle, with 1 to 5 leafy bracts and 2-5 well separated whorls of 3-6 flowers each. The densely hairy calyx forma a campanulate tube with 2 lips, 2–3 mm long with 4 upper teeth, 2.5-3 mm long and a lower tooth 7-10 mm in length. The purple, papilionaceous corolla has a banner 5-7 mm long with a short spur, the wings are 4-6 mm long and the keel 4-5 mm long. The fruit is a hairy, 1-seeded legume, 7-9 mm long with a short beak, and mostly enclosed by the calyx. Silverleaf scurf-pea blooms from July into September on prairies, hillsides, open woodlands, sand dunes and in stream valleys throughout South Dakota.

  Synonym: Psoralea argophylla,

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  Fabaceae : Pediomelum esculentum

  R. Neil Reese

  Pediomelum esculentum is a perennial herb with a tuberous-thickened root, 4-10 cm below ground and with 1-3 caudices extending to the soil surface, producing 1-3 simple or rarely branched stems, 8 to 30 cm in height and covered with a dense pubescence. The alternate leaves are palmately compound with 5 leaflets attached to a petiole that is 5-10 cm long, with stipules 1-2 cm long. The leaflets are elliptic to ovate, 2–4 cm long, 7-18 mm wide, narrowing at the base, rounded, blunt or pointed at the tip. The upper surface is usually nearly smooth, and the lower surfaces are covered in flattened hairs. The inflorescences are axillary spike-like racemes, 5–12 cm long including the peduncle, and the spikes 2-2.5 cm wide. The calyx tube is 5-6.5 mm long, with 5 teeth, the upper 4 are 5-7.5 mm long, the middle 2 partially united, and the lower-most tooth 6-8 mm long. The papilionaceous corolla is blue with clawed (constricted at the base) petals, the petals beyond the claws measure: banner 9-13 mm, wings 9-13 mm and the keel 4-5 mm long. The fruit is an ovoid, single-seeded legume, 5-7 mm long, enclosed in the calyx. Prairie turnips bloom from May into July in prairies, open woodlands, on hillsides and in stream valleys throughout South Dakota.

  Synonym: Psoralea esculenta

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  Fabaceae : Thermopsis rhombifolia

  R. Neil Reese

  Thermopsis rhombifolia is a perennial rhizomatous herb, with 1 to several ascending to erect stems, 15–60 cm tall, with or without a covering of short, stiff hairs. This species is often colony forming in open prairies. The alternate, palmately trifoliate leaves have leaflets that are ovate, 15–50 mm long and 10-20 mm wide, with a few to many appressed hairs. The inflorescence consists of subterminal racemes, 3–10 cm long. The calyx forms a hairy, bilabiate tube, 4-5 mm long, the upper lip having 2 united teeth, 3-4 mm long , and the lower lip with 3 teeth 2-3 mm long. The papilionaceous corolla has yellow petals, the banner often has purple spots and is 17-22 mm long, the wings are 15- 18 mm long, and the oblong keel is 14-16 mm long. The flowers have 10 separate stamens. The fruit is a legume, 3–8 cm long with 3 to 10 seeds, constricted between the ~5 mm long seeds. Goldenpea blooms from April into June on open prairies, hillsides and woodlands in western South Dakota.

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  Fabaceae : Vicia americana

  R. Neil Reese

  Vicia americana is a rhizomatous, perennial herb, the stems sprawling to climbing, 20-100 cm long and smooth to having a sparse covering of hairs . The alternate leaves are compound pinnate with 4 to 8 pairs of elliptical to linear leaflets 10-38 mm long , a pair of stipules ~8 mm long, and with a tendril at the end of the leaf. The inflorescences are racemes in the axils of the upper leaves. The peduncles are well developed with 3-10 flowers. The calyx forms a tube 3.5-5.5 mm long with unequal teeth, the upper short and broad the lower narrower and pointed, 1.2-4 mm long. The papilionaceous corolla is blue to purple, rarely white. The banner is 12-25 mm long and the wings and keel shorter. The fruit is a legume, 2.5-3.5 cm long with 2-14 seeds. American vetch blooms from May to July in a variety of dry, open to moist, shaded habitats; mixed grass prairie, sagebrush steppe, meadows, pine forest, and deciduous woodlands throughout South Dakota.

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  Fagaceae : Quercus macrocarpa

  R. Neil Reese

  Quercus macrocarpa is a deciduous coarse shrub to large tree, with deeply furrowed bark, growing up to 30 m in height and with the trunk more than 1 m in diameter. The simple, alternate leaves are obovate, pinnately lobed, 10-25 cm long and 5-15 cm wide. The leaves are usually shiny green on the upper surface and silvery due to star-shaped hairs on the lower surface and can vary greatly in size and shape depending on location and climate. Burr oak is monoecious, the green male flowers develop in pendulous catkins, each flower with a 5-lobed calyx and 5-10 stamens. The green female flowers are solitary or in small clusters in the axils of new growth, have 6 sepals and an ovary embedded in the surrounding tissues, with styles exerted. The fruit is a nut (acorn) surrounded by a deep cup, the margins and sides often fringed, that envelops half or more of the ovoid nut that is up to 4 cm long and 4 cm wide. Burr oak flowers in April and May in upland forests and along lake shores in much of South Dakota.

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  Fumariaceae : Dicentra cucullaria

  R. Neil Reese

  Dicentra cucullaria is perennial herb, which grows 6 cm to 30 cm in height, with the flower stems and basal leaves rising directly from a scaly rootstock. The erect to ascending basal leaves have long petioles (5-15 cm}, the compound pinnatifid blades are ovate to triangular, 10-26 cm long, divided 2-3 times into lacy segments 1-3 mm wide, with entire margins. The flowering stems (scapes) are 10-30 cm tall, terminating in a raceme of 3-15 flowers, subtended by whitish bracts. The flowers are shaped like pantaloons. The 2 membranaceous sepals are white, sometimes streaked with purple, 2-3.5 mm long and 1.5-2.5 mm wide. The 4 white petals are yellow tipped, the outer 2 petals are spurred 10-15 mm long, the inner pair, oblanceolate, 7-12 mm long and convergent coherent at the top. The fruit is a capsule, 10-15 mm long, 3-6 mm in diameter. Dutchman’s breeches bloom from March into May in moist woods in eastern South Dakota.

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  Gentianaceae: Frasera speciosa

  R Neil Reese

  Frasera speciosa is perennial herb with a simple, erect stem, 20–150 cm in height, that is smooth to having a covering of tiny, scattered hairs. It grows from a woody base surrounded by a rosette of large oblanceolate leaves that measure 7–25 cm long. The lanceolate cauline leaves are whorled, smaller and more linear than the basal leaves. The inflorescence is a tall, erect panicle with flowers densely clustered at the top and spread out in separated clusters below. The numerous whorls of flowers are each subtended by gradually reduced, leafy bracts. The flowers have a calyx of 4 narrow, green pointed sepals, 8–15 mm long, and a corolla of 4 broad, yellow green pointed petals, 1-2 cm long, each with purple spots and two fringed nectary pits at the base. There are four stamens tipped with large anthers and a central ovary. The plant is monocarpic, growing as a rosette of leaves for several years and only producing a flowering stem once before it dies. The fruit is an oblong capsule, 1–2 cm long. Monument plant blooms from May to August depending upon elevation. It grows in meadows, woodlands, and mountain forests, primarily at moderate to high elevations in western South Dakota.

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  Gentianaceae : Gentiana andrewsii

  R. Neil Reese

  Gentiana andrewsii is perennial herb growing 10-70 cm tall, the stems smooth to minutely hairy. The simple, opposite leaves are 1.8-8.4 cm long and 0.5-3.5 cm wide, sessile, tapering to a point, and the leaves tend to become larger as they ascend the stem. The inflorescence is a dense terminal cluster of flowers, occasionally with additional clusters in the axils of upper nodes. The calyx tube is 10-12 mm long with 5 lanceolate lobes 4-10 mm long. The blue to purplish, occasionally white, corolla forms a 2.8-4 cm long, closed tube, the petals incurved, with the flowers resembling large buds. The fruit is a capsule, ~25 mm long, and wrapped with the dried petals and contains numerous winged seeds. Closed bottle gentians bloom in August and September in wet meadows, prairies and woods in western and northeastern South Dakota.

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  Gentianaceae : Gentiana puberulenta

  R. Neil Reese

  Gentiana puberulenta is a perennial herb with simple, erect to ascending stems, rarely branched, the stems typically reddish tinged, with a covering of minute, soft hairs, and growing 15-50 cm in height. The simple, opposite leaves are sessile to subsessile, lanceolate, 1-5.5 cm long and 0.3-2 cm wide, with entire margins. The leaf pairs are at right angles to those above and below. The inflorescences are in clusters of 3-10 flowers at the top of the stem and sometimes also in the upper leaf axils. The calyx forms a tube, 7-18 mm long with lobes, 4-18 mm long. The blue purple to rose-violet corolla is funnel-shaped, 3-4 cm long, with the lobes erect to spreading. Inside the tube, the base of the petals is white with dark blue stripes or streaks. The fruit is a capsule that contains numerous winged seeds. Downy gentian blooms from August into October in drier prairies and upland woods on the eastern and western borders of South Dakota.

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  Geraniaceae: Geranium viscosissimum

  R Neil Reese

  Geranium viscosissimum is a perennial herb growing with 1 to a few branching stems that form clumps. The stems, 30-90 cm tall, generally have short, stiff hairs below and longer hairs toward the top near the flowers, with glands throughout, the foliage is sticky to the touch. The petiolate leaves are mostly basal, with flat stiff hairs and glands that exude the sticky substance. The blades are 5-10 cm wide, palmately lobed with 5-7 sharply toothed divisions. The few culm leaves are mostly opposite, nearly sessile and somewhat smaller than the basal leaves. The inflorescence consist of small clusters of two to several pedicellate flowers attached to axillary peduncles. The 5 sepals are 8-12 mm long, pointed with short hairs on the tips. The 5 petals are pink to purple, 14-20 mm long, with long hairs toward the base and darker stripes converging on the center. There are 10 fertile stamens and a 5-parted style. The fruit are capsules with glandular-stiff-hairs and are shaped like an upraised crane's bill. Sticky geranium blooms from May into August in open woods and along streambanks in western South Dakota.

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  Grossulariaceae : Ribes americanum

  R. Neil Reese

  Ribes americanum is a perennial shrub, with erect to ascending, unarmed stems, growing 1-1.5 m tall. The younger stems are hairy, and dotted with yellow glands, becoming smooth and gray to black with age. The simple, alternate leaves are nearly round in shape, 3-8 cm long, with 3 deeply parted lobes and 2 shallow lobes at the outer edges. The leaf margins have sharp to rounded teeth, the upper leaf surface is smooth, and the lower surface is covered with hairs and small glands. The inflorescences are composed of hairy, axillary, drooping, racemes with 6-15 flowers. The calyx is tawny brown at the base, becoming greenish white above, 8-10 mm long, the hairy, bell-shaped hypanthium is 3-4.5 mm long, with 5 sepal spreading to reflexed lobes, 4-5 mm long. The 5 petals are white 2-3 mm long, inserted at the top of the hypanthium. The 5 stamens are inserted between the petals, have a broad base, are tapered toward the top. The fruit is a black, ovoid berry, 6-10 mm in diameter, with persistent floral remnants on the end. Black currant blooms in May and June on the edges of woods, in moist ravines and along streambanks in much of South Dakota.

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  Grossulariaceae : Ribes aureum var. villosum

  R. Neil Reese

  Ribes aureum var. villosum is a perennial woody shrub, erect to arching main stems are 1-2 long, the younger stems and branches light brown, darkening with age. The stems are unarmed. The alternate, simple leaves develop directly on the branches of the current year and in clusters on projections from older stems. The leaf petioles are 2-5 cm long, the blades about the same length, broadly diamond to oval shaped, with 3 main rounded or bluntly pointed lobes, occasionally more, often further divided into shallow lobes. The margins are entire, or with a few blunt to rounded teeth. The inflorescence consists of axillary racemes of 3-8 flowers on peduncles 3-6 mm long. The yellow calyx tube is 10-14 mm long with 5 reflexed lobes, 3-5 mm long and showier than the corolla. The corolla has 5, erect, yellow petals, 2-3.5 mm long, often with all of the petals or their distal ends turning red. There are 5 stamens 1-2 mm long, attached to the hypanthium opposite the sepals. The fruit is a globose berry, 7-9 mm in diameter, greenish yellow and turning black as it matures. Buffalo currant blooms in April and May on dry, open hillsides, along the edges of thickets and streambanks, predominantly in western South Dakota.

  Synonym: Ribes odoratum

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  Grossulariaceae : Ribes hirtellum

  R. Neil Reese

  Ribes hirtellum is a perennial shrub, with erect to ascending stems with 1-3 nodal spines or often lacking these spines, the stems growing 0.5-1.5 m in height. The internodal prickles are few when present. The upper stems develop thin gray bark, shedding away along with any prickles, and the older branches are brown. The simple, alternate leaves are usually clustered on short lateral shoots, with slender, hairy petioles are up to 5 cm in length, often longer than the blades. The blades are almost round in outline, 1-5-3.5 cm long and 2-4 cm wide, with 3 major lobes and 2 smaller outer lobes. The margins have shallow, rounded teeth. The flowers are solitary or in small clusters along the stem, with slender, hairy pedicels 5-8 mm long. The flower parts form a yellow to lightly purplish, bell-shaped, hypanthium that is 5-8 mm long with 5 light green, flared sepals 3-4 mm long, and with 5, erect petals, 1-2 mm long. There are 5 stamens, opposite the sepals, 3-5 mm long, exerted above the petals. The fruit is a smooth, blue to black, ovoid to spherical berry, 8-10 mm in diameter, with persisting floral remnants on the end. Hairystem gooseberry blooms in May and June in rocky woods, along hillsides, in ravines and thickets along the eastern edge and western half of South Dakota.

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  Hydrophyllaceae : Hydrophullum virginianum

  R. Neil Reese

  Hydrophyllum virginianum is a rhizomatous perennial herb with stems growing 10 to 90 cm in height. It has basal and alternate cauline leaves that are deeply pinnately divided, 5-30 cm long and 5-15 cm wide, with 5-9 ovate lanceolate to rhombic segments, each up to 11 cm long with the lowest pair distinct. The petioles are 5- 25 cm long and the leaf blades often have white markings that look like water spots. The inflorescence consists of 1-several subcapitate clusters of flowers, the peduncles 2-20 cm long, lifting the flowers above the leaves, and each flower has a pedicel up to 1 cm in length. The 5 linear lobes of the calyx are 4-7 mm long and have hairs along the edges. The bell-shaped corollas are white to purple, the tube 3-5 mm long with 5 lobes 3-5 mm long. The stamens are exerted 4-8 mm beyond the petals and the style is exerted by 5-10 mm. The fruit is a 2-seeded capsule. Waterleaf blooms from May into July in mesic woodlands in eastern South Dakota.

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  Irdaceae : Iris missouriensis

  R. Neil Reese

  Iris missouriensis is a rhizomatous perennial herb with erect, leafless. flower stalks (scapes) 25-60 cm tall. The basal leaves are linear, 25-45 cm long and usually less than 1 cm wide. The 1-2 flowers emerge from a spathe, 5-7.5 cm long. Each flower has 3 light to dark blue, spreading or reflexed sepals, 4-6 cm long, lined with purple and with a whitish blotch at the base, and three smaller, upright blue petals. There are 3 stamens opposite the sepals. The fruit is an oblong, 6 angled capsule, 5-8 cm long. Western blue flag blooms in June and July in wet meadows, along streambanks and open woodlands in western South Dakota.

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  Iridaceae : Sisyrinchium campestre

  R. Neil Reese

  Sisyrinchium campestre is a perennial grass-like herb with narrow, winged stems, 10-40 cm tall and 1-2 mm wide. The basal leaves are about 1/2 to 2/3 the length of the flowering stems. The flowers emerge from a sessile spathe, the outer bract 2.5-4.5 cm long and the inner bract about ½ the length, with a pedicel that is exerted just beyond the spathe. The 6 tepals are up to 10 mm long, white to pale blue, sometimes having bluish stripes, rounded at the tip with a small, needle-like projection. The fruit is a rounded capsule, 3-6 mm in diameter. White-eyed grass blooms from April to June in prairies and open woods in eastern South Dakota.

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  Juglandaceae : Juglans nigra

  R. Neil Reese

  Juglans nigra is a large tree with brown bark that grow to 25 m tall with a trunk up to 1 m in diameter in a forest stand. Individual specimens growing under ideal conditions can grow much larger. Young twigs are green and covered with glandular hairs. The alternate, compound palmate leaves grow to 50 cm long, the 11-23 leaflets are sessile, oblong lanceolate, pointed at the tip and usually with small teeth along the margins. The trees are monoecious, with green male flowers in catkins up to 12 cm long, each with about 4 sepals and 8-40 stamens. The female flowers are terminal on new growth in clusters of 1-several flowers, each with 3 small bracts and a hairy pistil with a short style and 2 yellow green stigmas. The fruit is a globose, yellow green turning brown nut, 5 cm in diameter, containing a nut 4 cm in diameter. Black walnut blooms in April and May. This species is native to the southeastern corner of South Dakota, but has been planted in windbreaks and yards state wide, becoming naturalized throughout the state.

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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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  Lamiaceae: Agastache foeniculum

  R. Neil Reese

  Agastache foeniculum is a perennial rhizomatous herb, which grows 0.6 m to 1 m in height. The stems are square with opposite ovate to broad to lanceolate simple leaves, greenish above and whitish underneath due to fine, appressed hairs the leaf margins are finely toothed. When crushed the leaves smell of anise. Flowers open in July and August and are arranged in a terminal spike-like raceme. The tubular calyx is 5 toothed 5-7 mm long and lavender toward the tips. The corolla is 2-lipped 7-10 mm long and lavender to bluish-purple in color. Stamens 4 and exerted from corolla. Pistil with 2 carpels with a 2-part style. Fruit are 4 nutlets. Lavender hyssop blooms from June through September. This species is commonly found in upland woods and prairies in both eastern and western South Dakota.
  
  
  

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  Lamiaceae : Mentha arvensis

  R. Neil Reese

  Mentha arvensis is an aromatic, perennial, rhizomatous herb with square, simple to branched, ascending to erect stems growing from 30-90 cm tall. The stems are usually hairy to nearly smooth with rings of hairs at the nodes. The simple, opposite leaf blades are lanceolate to ovate, 2.5-12 cm long and 5-40 mm wide, slightly small toward the top, with the upper surface generally without hairs and the lower surface with hairs along the veins. The margins are toothed with hairs along the edges and the petioles are 3-15 mm long. The inflorescence consist of paired 8-30 flowered cymes in the axils of leafy bracts. Each flower with a pedicel 1-3 mm long. The 5-lobed hairy calyx is tubular to bell-shaped, 2.5 -3.3 mm long, with teeth about ¼ length of the tube. The weakly bilabiate corolla is whitish to lavender in color, 4.5-6.5 mm long. The 4 stamens and the style are exerted from the corolla by 1-2 mm. the fruit are 4 nutlets. Field mint blooms from July into September in moist shaded sites, streambanks, lake shores and marshes throughout South Dakota.