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  Pinaceae: Picea glauca

  R. Neil Reese

  Picea glauca is a tall, evergreen conifer that can reach heights of 20 to 30 meters or more. It has a conical crown with horizontal to slightly drooping branches, a straight trunk with thin, scaly, gray-brown bark. Needles are attached individually and arranged spirally around the twig. They are stiff, sharp, four-sided, 1 to 2.5 cm long, and bluish green to gray green with a whitish waxy coating. Male cones are small, cylindrical, and yellowish, producing pollen released from May to June. Female cones are green when young, maturing to brown in fall, typically 3–7 cm long, with thin, flexible scales. They mature from September through October, with seed dispersal occurring shortly after. The bark, needles, and cones are distinctive to this species. White spruce is native to boreal forests across much of North America, including parts of South Dakota, favoring cooler, moist environments and well-drained soils. Black Hills spruce is a variety of white spruce that is native to a geographically isolated area in and around the Black Hills of South Dakota. It was originally called Picea glauca var. densata, but many experts now designate it as Picea glauca ‘Densata’ because its differences from the species are judged insufficient to justify classification as a botanical variety.

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  Pinaceae: Pinus contorta

  R. Neil Reese

  Pinus contorta is a medium-sized evergreen conifer reaching heights of 15 to 30 meters. It has a narrow, conical crown with dense branches. The bark is thin and scaly on young trees, becoming thick and deeply furrowed with age. Needles occur in pairs (2 per fascicle), are slender and sharp-pointed, 3 to 7 cm long, often twisted and dark green. Male cones are small, cylindrical, 1 to 3 cm long and about 0.5 to 1 cm wide, releasing pollen from May to June. Female cones are oval to conical, 3 to 7 cm long and 2 to 3 cm wide, often serotinous (remaining closed until exposed to fire or heat), they mature over two seasons, changing from a purple green to a light brown color in September or October. Lodgepole pine is native to the Black Hills of South Dakota where it grows in cooler, moist, higher elevation sites, often mixed with ponderosa pine and spruce. It is well adapted to fire ecology.

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  Pinaceae : Pinus ponderosa

  R. Neil Reese

  Pinus ponderosa is a large evergreen tree with a pyramid-shaped crown that broadens with age and can reach 35 m in height. The trunk is straight, gray brown and furrowed when young, becoming scaley and gray mixed with orange brown with age, and the branches are gray black in color. The needle-like leaves are clustered toward the branch tips, usually 3 (2) per fascicle, 8-20 cm long, with small teeth along the margins. The fascicles emerge from a membranous, orange brown, deciduous sheath that is 1.5-2.5 cm long. Ponderosa pines are monoecious, the male cones are yellow orange, cylindrical, 1.5-3 cm long, in axillary clusters of 10-20 cones. The female cones are brown, woody, broadly ovoid, 6-12 cm long, 6-8 cm wide, and mature in the second year. Each cone scale has a thin prickle on the outer side. The seeds are in pairs underneath the scales, 6-7 mm long with a papery wing 3-4 times as long as the seed. The cones release pollen in May and June on low mountains and rocky hillsides in western and southcentral South Dakota.

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  Rhamnaceae: Ceanothus herbaceus

  R. Neil Reese

  Ceanothus herbaceous is a deciduous, perennial, woody, bushy shrub growing up to 1 m tall. The simple, alternate leaves are 3-nerved, oblong to oblanceolate, the margins with small teeth and glandular when young. The upper surface of the leaves usually have a slightly white waxy covering and the lower surface with long white hairs. The inflorescence consists of terminal panicles at the ends of the leafy branches of the new year, on peduncles 1-5 cm long. the tiny white flowers have a short calyx tube with 5 lobes 1.6 mm long, 5 hooded petals, ~2.5 mm long, constricted (clawed) for ½ their length. There are 5 stamens with a 3-lobed ovary surrounded by a 10-lobed collar, 1.5 mm wide. The fruit is a 3-lobed capsule, 3-4.5 mm wide. New Jersey tea blooms in May and June on prairies and open wooded hills in western South Dakota.

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  Rhamnaceae : Ceanothus velutinus

  R. Neil Reese

  Ceanothus velutinus is an evergreen, perennial, spreading shrub growing 0.5-2.5 m tall, lacking spines and forming large colonies. The simple, alternate leaves are 3-nerved, ovate to ovate-elliptic, 4-8 cm long, the margins with small glandular teeth. The upper surface of the leaves are shiny green and often sticky, and the lower surface is pale with long often velvety hairs. The inflorescence consists of axillary, dense panicles. The tiny white flowers have a short calyx tube with 5 incurved lobes < 2 mm long, 5 recurved hooded petals, 2-2.5 mm long, abruptly constricted (clawed). There are 5 upwardly curved stamens with a 3-lobed ovary surrounded by a 10-lobed disk. The fruit is a 3-lobed capsule, 5-6 mm wide, with a slight crest above the middle. Mountain balm blooms in June and July on dry, open wooded hillsides in western South Dakota.

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  Rhamnaceae: Rhamnus cathartica

  R. Neil Reese

  Rhamnus cathartica is a deciduous shrub or small tree typically growing 2 to 6 meters tall. The stems are slender and often thorny, with dark brown to blackish bark that becomes scaly with age. Leaves are opposite or sub-opposite, ovate to elliptic in shape, 3 to 7 cm long and 2 to 4 cm wide, with finely serrated margins and a glossy dark green upper surface contrasting with a paler underside. The leaves have three to five prominent veins curving toward the leaf tip. The small, inconspicuous flowers bloom from May to June, usually in clusters of two to five in leaf axils. Flowers have four greenish-yellow petals about 2 to 3 mm long and four sepals of similar size and shape. Each flower contains four stamens with filaments about 1 to 2 mm long and yellowish anthers. The pistil is single with a two-chambered ovary. Fruit matures from August through September as a small, round drupe about 6 to 9 mm in diameter, glossy black when ripe, containing two to four seeds. Common buckthorn is native to Europe and western Asia and was introduced to South Dakota in windbreaks. It is now an invasive species found in woodlands, fields, and disturbed sites throughout the state, often forming dense thickets that outcompete native vegetation.

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  Rosaceae: Amelanchier alnifolia

  R. Neil Reese

  Amelanchier alnifolia is a perennial deciduous shrub or small tree which grows 1 m to 5 m in height (occasionally taller in very moist sites) and often forms thickets. The bark is thin, light brown and tinged with red; smooth or shallowly fissured. The leaves are alternate, oval to nearly circular, 2–5 cm long and 1–4.5 cm wide. The margins are entire below and toothed mostly above the middle. Serviceberries have white to pink flowers, borne in racemes, and bloom from April to June. Five sepals are green 1-3 mm long, triangular with the tips recurved. The 5 petals are white, 5-12 mm long and obovate, A shallowly cupped hypanthium of 3-4 mm is visible at anthesis. Each flower has 10-20 stamens and a pistil with 5 styles. The fruit is a deep red to dark purple, berry-like pome, 10-15 mm long and 8-11 mm wide. This species is commonly found open slopes and along streams throughout much of South Dakota.

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  Rosaceae: Crataegus chrysocarpa

  R Neil Reese

  Crataegus chrysocarpa is a perennial multi-stemmed shrub, 2–4 m tall, with a rounded top, straight to curved thorns 3–6 cm long, the young stems are light brown and become gray with age. The alternate, simple leaves have blades that are ovate, 2–6 cm long, shallowly lobed, the lobes pointed. The margins are sharply toothed on the upper half, with glands on the tips of the larger teeth and with small teeth to smooth at the bottom. The blade surfaces have sparsely appressed hairs. The petioles are 1-4 cm long, with 6-9 mm long stipules that are rapidly deciduous. The inflorescence consists of small terminal clusters of 5- to 12 flowers at the ends of lateral branchlets. Each flower has a hairy, cup-shaped hypanthium with 5 sepals 2–4 mm long, and glandular margins. The 5 petals are round, white, 7–10 mm long and abruptly narrowed into a short claw. There are 10 stamens and an inferior ovary with 3 or 4 styles. The fruit is a red pome, 8–15 mm in diameter, sparsely pubescent when young and later becoming smooth. Fireberry hawthorn blooms in May and June on open wooded hillside and prairie ravines of the eastern and western borders of South Dakota.

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  Rosaceae: Crataegus douglasii

  R. Neil Reese

  Crataegus douglasii is a deciduous shrub or small tree with a deep, extensive root system and may form dense thickets by root suckering. Stems are erect, often branched, reaching heights of 3–8 meters. The bark is smooth and gray on young stems, becoming rougher and fissured with maturity. Leaves are alternate, simple, ovate to oblong, generally 3 to 8 centimeters long and 2 to 5 centimeters wide, with finely serrate margins and petioles about 1 to 2.5 centimeters long. Flowering occurs from May to June, producing clusters of white flowers about 1.5 to 2 centimeters in diameter. Each flower has five petals approximately 5 to 8 millimeters long and wide, and five greenish sepals about 2 to 4 millimeters long and 1 to 2 millimeters wide. There are typically 20 to 25 stamens inserted around a superior ovary, with filaments about 4 to 6 millimeters long and yellow anthers. The pistil consists of a single ovary with a short style and a lobed stigma. The fruit is a pome, rounded to slightly flattened, about 10 to 15 millimeters in diameter, dark purple to nearly black when mature, ripening in late summer to early fall. Black hawthorn is native to western North America and can be found in South Dakota, primarily in riparian woodlands, foothills, and open forests.

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  Rosaceae : Dasiphora fruticosa

  R. Neil Reese

  Dasiphora fruticosa is a perennial, spreading, bushy shrub with erect branches 20-100 cm tall. The young branches are covered with soft white hairs that are lost with age, the bark turning red and becoming shredded. The alternate, compound odd-pinnate leaves have petioles up to 12 mm long and brownish stipules 6-12 mm long. The blades have 3-7 linear to narrowly obovate leaflets, 10-20 mm long, with entire margins and hairs on both surfaces, the top with scattered white hairs and the bottom with a denser, gray covering. The inflorescence consist of single axillary flowers and small terminal cymes of 2-5 flowers. The flowers have a saucer-shaped hypanthium, 3.5-5 mm wide, with 5 spreading, pointed, green sepals 4-6 mm long, alternating with small bracts. The 5 yellow, spreading, round to club-shaped petals are 6-13 mm long. There are 20-30 stamens, inserted on the edge of a nectar ring, and numerous hairy pistils on an elongated receptacle. The fruit is a cluster of light brown, hairy, ovoid achenes, each < 2 mm long. Shrubby cinquefoil blooms from June into August on hillsides, meadows and in canyons in western South Dakota.

  Synonym: Potentilla fruticosa

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  Rosaceae : Prunus americana

  R. Neil Reese

  Prunus americana is a perennial, deciduous shrub or small tree, 2-6 m tall, usually forming thickets from root-suckers. There are generally many stems per plant, the older stems bark becomes dark gray and scaly, the younger stems are reddish brown to gray with a flaking waxy cuticle, typically smooth but occasionally with persistent hairs. The branches spread widely, with older lateral twigs developing into spines up to 7 cm long. the simple, alternate leaves have petioles 8-20 mm long, often with glands near the base of the blade and stipules 5-14 mm long. The leaf blade is ovate to lanceolate-ovate, 6-10 cm long, sharply pointed, the margins with teeth or doubled teeth, green and smooth above and with hairs on the lower side. The inflorescence consists of axillary and terminal clusters o 2-5 flowers on smooth pedicels 7-20 mm long, and usually appearing before the leaves and remaining as the leaves develop. The flowers have a conical hypanthium ~3 mm long, the 5 green, reflexed sepals are 3-4 mm long with hairs on the upper side. The 5 oblong ovate white petals are constricted (clawed)8-12 mm long. there are 20-30 stamens inserted on the edge of the hypanthium in several rows, with a single 2-carpeled pistil, the style 12-15 mm long with a capitate stigma. The fruit is a fleshy drupe, yellow to reddish-purple, 2-3 cm long and 2-2.5 cm in diameter, often having a waxy coating. Wild plums bloom in April and May and ripen in August and September. They are common in woodlands, thickets, pastures, along streams and roadsides throughout South Dakota.

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  Rosaceae : Prunus virginiana

  R. Neil Reese

  Prunus virginiana is a perennial, deciduous shrub or small tree that forms thickets from root sprouts and grows 2-6 m in height. The bark on the trunk and branches is red brown to dark brown in color. The simple, alternate leaves have petioles 1-3 cm long, with stipules 2-4 mm long and large glands near the base of the blade. The blades are ovate to obovate, 4-12 cm long, 3-6 cm wide, the rounded and the tip pointed, with small teeth on the margins. The upper leaf surface is usually dark green and shiny and the lower surface gray green, occasionally with hairs along the veins. the inflorescences are dense racemes terminating leafy twigs of the season. Each flower has a bell-shaped hypanthium ~1.5 mm long with 5 deciduous sepals 1-1.5 mm long. The 5 white petals are rounded, 3-4 mm long. there are 20-30 stamens in several rows surrounding a single ovoid ovary ~ 1.5 mm long. the fruit is a round, deep red to almost black, fleshy drupe, 8-11 mm in diameter. Chokecherries bloom in April and May in open woodlands, canyons, on prairies and along streams and roadways throughout South Dakota.

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  Rosaceae: Purshia tridentata

  R. Neil Reese

  Purshia tridentata is a deciduous, woody shrub growing 1 to 3 meters tall with multiple slender, erect branches arising from a deep root system. The leaves are alternate and simple, measuring 1 to 3 cm long and 0.5 to 1.5 cm wide, with three distinct, obovate to spatulate lobes. The upper leaf surface is dark green and smooth, while the lower surface is lighter green and often covered with fine hairs giving a slightly fuzzy texture. Leaves are borne on petioles 2–5 mm long. The inflorescence consists of solitary flowers or small clusters born in leaf axils, blooming from April through June. The calyx comprises five small, narrowly triangular sepals about 3 to 5 mm long. The flowers have five pale to bright yellow petals each 10–15 mm long and slightly clawed at the base and are often fragrant. Stamens number about 15–30, inserted around the base of the ovary in a circle. The style is slender and elongated, ending in a small, rounded stigma. Fruits are achenes with a long, slender, beak-like tip, enclosed in a dry, papery cup or calyx. They mature from August through September. Rare but native in South Dakota, antelope bitterbrush occurs primarily in dry, rocky, and open shrublands in the southern Black Hills.

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  Rosaceae : Rosa arkansana

  R. Neil Reese

  Rosa arkansana is small perennial shrub growing from rhizomes, with a woody base and a mixture of woody and herbaceous stems that often die back to the ground each year. The 10-50 cm tall stems are sparkly to densely covered in unequal prickles. The alternate, petiolate leaves have stipules. The compound odd-pinnate blades have 7-11 obovate to elliptic leaflets, 1-4 cm long and < 3.5 cm wide, with small teeth on the upper 2/3 portion. The flowers are in corymb-like clusters, of 3 or more, at the ends of the new year’s branches and occasionally from side branches on the previous year’s growth. The rounded hypanthium has 5 sepals, 1.5-3 cm long and 3-5 mm wide, that are persistent with the fruit. The 5 white, pink to occasionally red petals are 1.5-3 cm long, obovate and usually notched. There are numerous stamens and 15-30 pistils that develop into achenes 3-5 mm long with long stiff hairs on one side. The accessory fruit (rose hips) contains the achenes. Prairie rose blooms from May into August on prairies, open woodlands and along roadsides throughout South Dakota.

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  Rosaceae: Rosa woodsii

  R. Neil Reese

  Rosa woodsii is a perennial, deciduous shrub. It typically forms upright to arching thickets and grows from a fibrous root system with extensive rhizomes, allowing it to spread vegetatively. Plants usually reach 0.5 to 2 meters in height. Stems are slender, brown to reddish, and armed with straight or slightly curved prickles of variable size. New stems are often hairy. Leaves are alternate, pinnately compound, usually with 5 to 9 leaflets. Leaflets are oblong to elliptic, 1–4 cm long and 0.5–2 cm wide, with sharply serrated margins. The upper surface is dull green and glabrous to sparsely hairy, while the lower surface may have fine hairs. A short petiole (up to 2 cm) is present, often glandular and hairy, with prominent, persistent stipules at the base that are broad, flat, and fused to the petiole for much of their length. Flowering occurs from May to July. Inflorescences are solitary or in small corymbs at the end of branches. Each flower is 3–5 cm across, with five free, green sepals (1–2 cm long, narrowly lanceolate, and sometimes glandular on the back) that are often persistent on the fruit. There are five pink petals, rounded and spreading, 1–2 cm long, notched at the tip. Numerous stamens (typically over 50) form a ring around the pistils, with yellow filaments and anthers. The pistils are numerous, each with a short style, enclosed within the hypanthium (floral cup). The fruit is a fleshy, bright red to orange, ovoid to globose hip, 1–2 cm in diameter, maturing from August to October. The hips persist into winter and provide an important food source for wildlife. Woods’ rose is native to South Dakota and occurs across the state in a wide range of habitats, including prairies, streambanks, woodland edges, and open forests.

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  Rosaceae : Rubus idaeus ssp. strigosus

  R. Neil Reese

  Rubus idaeus ssp. strigosus is the red raspberry native to North America. The plants are sub-shrubs from a perennial, rhizomatous rootstock, with stems that are semiwoody, erect to arching, 0.5-3 m in length, sparingly to copiously covered in prickles. The stems produce leaves the first year, leafy shoots and flowers from the leaf axils the second year, and then die back to the ground. The alternate, petiolate, compound leaves have 3 or 5 ovate to oblong leaflets 4-10 cm long. There are 1-2 pairs of lateral, unlobed, sessile leaflets, and a central leaflet, often 2 or 3 lobed, attached via a short rachis segment. Each leaflet has a pointed tip and rounded to heart-shaped base. The margins are single or double toothed, the upper surface is dark green, sparsely hairy to smooth and the lower surface is densely hairy, appearing silvery. The inflorescence consists of 1 to a few small axillary, leafy racemes each with several flowers. The hypanthium is flat to cupped, the green calyx has 5 reflexed lobes, 4-7 mm long, the 5 white, ascending, petals are narrowly oblong to spatulate, 4-6 mm long. there are numerous stamens and pistils inserted into a conic receptacle. The fruit is a cluster of red 1-seeded, finely hairy drupelets, 12-18 mm long. American wild raspberries bloom from May into July in open woodlands, on hillsides and along streambanks in counties scattered throughout South Dakota.

  Synonym: Rubus idaeus ssp. sachalinensis

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  Rosaceae: Rubus occidentalis

  R. Neil Reese

  Rubus occidentalis is a deciduous, woody bramble that forms arching or trailing canes up to 1.5–3 meters long. The canes are biennial, with first-year primocanes typically green and covered in fine hairs and sparse prickles, and second-year floricanes are brown, woody and more heavily armed with curved prickles. They usually die following fruit ripening. Leaves are alternate and compound, usually with three to five leaflets. Leaflets are ovate to lanceolate, 3 to 8 cm long and 2 to 5 cm wide, with serrated margins and pointed tips. The upper surface of the leaflets is dark green and slightly hairy; the underside is lighter green and more densely hairy. Petioles are 1 to 3 cm long. The inflorescence is a loose cluster of white to pale pink flowers blooming from May through July. Flowers have five broadly ovate petals, 10 to 15 mm long and 8 to 12 mm wide. The calyx consists of five ovate sepals, 5 to 8 mm long and 3 to 5 mm wide, often hairy on the outer surface. Each flower contains numerous stamens, typically 30 to 50, with filaments about 2 to 3 mm long and yellow anthers approximately 1 to 2 mm long. The pistils number 20 to 40 per flower, each slender, 2 to 3 mm long, tapering to a pointed stigma. Fruits mature from July through August as aggregate drupes about 1 to 1.5 cm in diameter, glossy black when ripe, each composed of multiple small drupelets. Black raspberry is native to South Dakota, and grows in open woods, forest edges, thickets, and disturbed sites, scattered throughout the eastern and southern parts of the state.

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  Rosaceae : Rubus parviflorus

  R. Neil Reese

  Rubus parviflorus is a perennial shrub that spreads by rhizomes, with erect, unarmed stems 0.5-3 m long, the younger stems having glandular hairs and the older stems developing gray, exfoliating bark. The simple, alternate leaves are palmately lobed, 6-20 cm long and 11-18 cm wide, and the leaf margins are doubly toothed. The petioles are 6-15 cm long, often with glandular hairs, with attached, lanceolate stipules, 5-12 mm long. the inflorescence is a terminal cluster of 3-7 flowers. The flowers have a small hypanthium with 5 sepals, 10-16 mm long, with a tail-like appendage about ½ the length , and 5white, obovate petals, 2-2.5 cm long. there are numerous stamens and many, simple pistils that are inserted in a conical receptacle. The fruit is a thimble-like aggregate of red drupelets that fall as a unit leaving the persistent receptacle. Thimbleberries bloom from May into July in open woods, hillsides and along streambanks in western South Dakota.

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  Rosaceae: Sorbus scopulina

  R. Neil Reese

  Sorbus scopulina is a perennial, deciduous shrub or small tree with a woody and fibrous root system. Mature plants are typically multi-stemmed and reach 2–6 meters in height. Stems are upright, slender, and brown to grayish, with smooth bark on young stems aging to slightly roughened with lenticels. Leaves are alternate, pinnately compound, 10–20 cm long, with 9–15 lanceolate to oblong leaflets per leaf. Each leaflet is 2–7 cm long and 0.7–2 cm wide, with serrated margins, a pointed tip, and a rounded or slightly tapered base; upper surfaces are dark green and glabrous, while lower surfaces are paler and may have sparse hairs, especially along the midrib. Petioles are present, 2–5 cm long, and leaf rachises may be slightly hairy. Flowering occurs from May to July, with dense, flat-topped corymbs 5–12 cm across, each bearing dozens of small, white, five-petaled flowers. The calyx has five small, green, triangular sepals, 1–2 mm long and 1 mm wide, fused at the base and persistent in fruit. Petals are five, white, oblong to ovate, 3–5 mm long and 2–3 mm wide, free and spreading. Each flower has 15–20 stamens with yellow anthers about 1.5 mm long. The pistil is compound (inferior ovary), formed by 3–5 united carpels, with 3–5 styles (sometimes fused at the base) and capitate stigmas. The fruit is a small, round pome, 6–10 mm in diameter, bright red to orange-red when mature in late summer to early fall (August–September). Greene’s mountain-ash is native to the Black Hills and western regions of South Dakota, where it inhabits moist forests, stream banks, canyons, and mountain slopes, typically in partial shade and well-drained soils.

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  Rosaceae: Spiraea lucida

  R. Neil Reese

  Spiraea lucida is a perennial, deciduous shrub with a fibrous root system and sometimes short, woody rhizomes or stolons, often forming loose clumps. Mature plants are typically 0.5–1.5 meters tall. Stems are upright to arching, slender, and brown to reddish, with smooth bark and occasional fine hairs on young growth. Leaves are alternate, simple, and oblong to elliptic or lanceolate, 2–7 cm long and 1–3 cm wide, with serrated or doubly serrated margins. The upper surface is shiny, dark green, and glabrous, while the lower surface is paler and may be sparsely hairy or glabrous. Petioles are present and short, 2–5 mm long. Flowering occurs from June to August, with dense, flat-topped to slightly rounded corymbs 3–7 cm across, each bearing numerous small, white to pinkish, five-petaled flowers, 6 to 10 mm in diameter. The calyx has five small, triangular sepals, 1–2 mm long, green, free, and persistent. Petals are five, white to pale pink, obovate, 2–4 mm long and 1–2 mm wide, free and spreading. Each flower has 20–30 stamens with yellow anthers about 1 mm long. The pistil consists of five separate carpels, each with a slender style and capitate stigma. The fruit is an aggregate of five small, dry, brown follicles, each 3–5 mm long, that split open at maturity in late summer (August–September) to release several tiny seeds. Shining meadowsweet is native to South Dakota and can be found in the Black Hills, western prairies, open woodlands, stream banks, and rocky slopes, especially in well-drained, sandy or gravelly soils with full sun to partial shade.

  Synonym: Spiraea betulifolia var. lucida

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  Salicaceae :Populus deltoides ssp. monilifera

  R. Neil Reese

  Populus deltoides is a large tree up to 40 m in height with a truck up to 2 m diameter at breast height, often branching near the base, ascending at a moderate angle and forming a very broad crown. The youn stens are olive brown to orangish, becoming grayish tan as they age, the main trunk and larger branches have tan bark the is deeply furrowed. The winter buds are brown, ovoid, resinous and large, 1-2 cm long. The simple, alternate, deciduous leaves are deltoid, 4-14 cm long, 4-15 cm wide, light green with rounded teeth and a pointed end. The petioles are long (3-13 cm) and laterally compressed. The trees are dioecious, the male trees producing staminate catkins 5-13 cm long with flowers containing up to 80 stamens. The female (pistilate) catkins are about the same length at flowering but elongating in fruit. The flowers contain a single pistil that forms an elliptic-ovoid, 3-4 valved capsule about 1 cm long containing 7-10 cottony seeds. Plains cottonwoods bloom in March into June, releasing seeds in June and July. Primarily riparian, the trees are found along streams, lakes and other moist areas throughout South Dakota.

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  Salicaceae: Populus tremuloides

  R. Neil Reese

  Populus tremuloides is a deciduous, fast-growing tree reaching 15 to 25 meters tall with smooth, pale greenish white to gray bark that becomes furrowed with age. The root system is extensive and shallow with vigorous lateral root suckering, allowing the tree to form large clonal colonies. Leaves are alternate, nearly round to broadly ovate, 4 to 8 cm long and 3 to 7 cm wide, with finely serrated margins and flattened petioles that cause the leaves to tremble in the wind. Flowers are produced in catkins; male and female catkins are on separate trees (dioecious). Male catkins are slender and cylindrical, 2 to 6 cm long and about 0.5 to 1 cm wide, releasing pollen from April to May. Female catkins are slightly larger, 3 to 8 cm long and about 0.7 to 1.2 cm wide, maturing from May through June. The fruit consists of small capsules, 5 to 10 mm long, that split open to release numerous tiny seeds attached to cottony hairs which aid in wind dispersal. Native to South Dakota, quaking aspen is widespread in the northern and mountainous regions, commonly found in mixed forests, riparian zones, and upland areas.

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  Salicaceae: Salix amygdaloides

  R. Neil Reese

  Salix amygdaloides is a deciduous shrub or small tree growing 6 to 12 meters tall. Young stems have smooth gray bark that becomes furrowed with age. Branches are slender, flexible, and often show a reddish or yellowish tint. Leaves are alternate, simple, narrowly lanceolate to elliptical, 5 to 12 cm long and 1 to 3 cm wide, with finely serrated margins. The upper leaf surface is dark green and mostly smooth, while the underside is paler and can be slightly hairy. Petioles are short, about 5 to 10 mm long. This species is dioecious, meaning male and female flowers grow on separate trees. Flowers emerge in early spring before or alongside leaves, arranged in slender catkins 2 to 6 cm long. Male catkins have multiple stamens, typically 2 per flower, with yellow anthers; female catkins are shorter and thicker, bearing flowers with a single pistil each, with long styles and feathery stigmas. Fruit is a small capsule, maturing in late spring to early summer, releasing tiny seeds surrounded by cotton-like hairs for wind dispersal. Peachleaf willow is native to South Dakota, commonly found along streams, floodplains, and moist bottomlands.

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  Salicaceae: Salix interior

  R. Neil Reese

  Salix interior is a deciduous shrub or small tree typically growing 3 to 8 meters tall. It often forms thickets by root suckering along riverbanks and sandbars. The bark on young stems is smooth and greenish to reddish-brown, becoming furrowed and grayish with age. Branches are slender and flexible. Leaves are alternate, simple, and lanceolate to narrowly elliptical, measuring 4 to 10 cm long and 1 to 3 cm wide. Leaf margins are finely serrated. The upper leaf surface is dark green and glabrous (smooth), while the underside is paler and often finely hairy. Petioles measure about 5 to 10 mm long. This species is dioecious, with male and female flowers on separate plants. Flowers appear in early spring (March–May), arranged in slender catkins 3 to 7 cm long. Male catkins are slender, 2–6 cm long, bearing numerous yellow stamens—typically 2 per flower. Female catkins are shorter and clustered, each flower containing a single pistil with long styles and feathery stigmas. Like other willows, the flowers lack true petals and sepals but have small floral scales (bracts) subtending each flower. The fruit is a small capsule that splits open to release numerous tiny seeds surrounded by cottony hairs which aid in wind dispersal. Sandbar willow is native to South Dakota, commonly growing on sandbars, riverbanks, and other moist, sandy or silty sites throughout South Dakota.

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  Salicaceae: Salix planifolia

  R. Neil Reese

  Salix planifolia is a deciduous shrub or small tree growing typically 0.5–2 meters tall, often forming dense thickets in alpine and subalpine environments. Branches are slender, flexible, and may be slightly hairy when young, often having a reddish or grayish hue. The bark on young stems is smooth, becoming furrowed with age. Leaves are alternate, simple, and broadly lanceolate to ovate, typically 3 to 8 cm long and 1 to 3 cm wide. Leaf margins are finely serrated or sometimes nearly smooth. The upper leaf surface is dark green and glabrous, while the underside is paler and often covered with fine hairs. Petioles are short, about 3 to 8 mm long. This species is dioecious, with male and female flowers borne on separate plants. Flowers emerge in spring to early summer (April–June), as slender catkins 2 to 6 cm long. Male catkins are slender, typically 2–5 cm long, bearing numerous stamens (usually 2 per flower) with yellow anthers. Female catkins are shorter, bearing flowers each with a single pistil with a long style and feathery stigmas. There are small, leaf-like floral scales (bracts) subtending each flower. The fruit is a small capsule that splits open to release numerous tiny seeds surrounded by cottony hairs. Planeleaf willow is native to South Dakota, growing in mountainous regions of the Black Hills, in moist to wet sites, including stream banks and alpine meadows.