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  Ulmaceae: Celtis occidentalis

  R. Neil Reese

  Celtis occidentalis is a perennial, medium to large deciduous tree. It grows from a deep, spreading root system that is sometimes shallow and wide, allowing for some basal sprouting. Trees can reach heights of 9–20 meters (occasionally taller), with a trunk up to 60 cm or more in diameter. Young bark is thin, gray, and smooth; mature bark is distinctively ridged with warty, corky projections. Branches are spreading and may be somewhat pendulous. Leaves are alternate, simple, ovate to lanceolate, 7–12 cm long and 3–7 cm wide, with an unequal (oblique) leaf base, sharply toothed margins, acuminate tips, and rough upper surfaces; leaves are attached by slender, slightly pubescent petioles. Both young stems and leaves may be slightly hairy, especially below. Flowering occurs from April to May before or with leaf emergence. Flowers are small, greenish and inconspicuous, borne singly (staminate) or in small cymes (bisexual/pistillate) in the leaf axils; individual flowers have 4–5 petal-like sepals. Flowers are mostly monoecious (male and female flowers on the same tree) but can be functionally unisexual. Fruit is a single-seeded, round drupe (hackberry), 6–10 mm in diameter, green turning deep purple or dark red at maturity in late summer to fall. The thin-shelled drupe contains a hard seed and a thin layer of sweet, edible flesh. Common hackberry is native to South Dakota, found in riparian forests, woodland margins, shelterbelts, river bluffs, and occasionally in upland prairies, statewide but especially common in eastern river valleys and shelterbelts.

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  Ulmaceae: Ulmus americana

  R. Neil Reese

  Ulmus americana is a large, deciduous tree with a deep, widespread woody and fibrous root system. Mature trees typically reach 20–30 meters in height, with some specimens exceeding 40 meters. The trunk is stout, with grayish-brown bark that becomes deeply furrowed and ridged with age. Branches form a broad, vase-shaped crown with arching limbs. Leaves are alternate, simple, and ovate to elliptical, 7–15 cm long and 5–10 cm wide, with doubly serrated margins and an asymmetrical, uneven base. The upper leaf surface is dark green and rough to the touch with coarse hairs, while the lower surface is lighter green and softly hairy, especially along veins. Petioles are short, 5–15 mm long. Stipules are present, small, and fall early. Flowering occurs in early spring (March to April) before leaf emergence, with wind-pollinated, perfect but apetalous flowers arranged in dense, axillary clusters (cymes) 1–3 cm long. The calyx is inconspicuous; petals are absent. Stamens number 4–5 per flower with elongate filaments and yellow anthers. The pistil has a single ovary with a slender style and two stigmas. The fruit is a flat, round samara, 1–1.5 cm in diameter, with a central seed surrounded by a papery wing, maturing from April to May. American elm is native to South Dakota and occurs primarily in moist bottomlands, floodplains, riverbanks, and rich woodlands, favoring deep, fertile, well-drained soils in full sun to partial shade.

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  Vitaceae: Parthenocissus vitacea

  R. Neil Reese

  Parthenocissus vitacea is a vigorous, deciduous woody vine capable of climbing 10 to 20 meters high by means of tendrils that allow it to attach to surfaces such as trees, rocks, or buildings. The root system consists of a robust, woody perennial base from which the climbing stems arise annually. The leaves are alternate and petiolate, with petioles 5 to 12 cm long. Each leaf is palmately compound with five leaflets, each leaflet ovate to lanceolate, 5 to 12 cm long and 3 to 7 cm wide, with serrate margins and a glossy dark green upper surface that turns reddish-purple in fall. The flowers are small, greenish, and inconspicuous, arranged in loose, branched panicles blooming from June through August. Each flower has five sepals that are lanceolate to ovate, 1.5 to 3 mm long and about 1 mm wide. The corolla consists of five tiny petals about 2 to 4 mm long and 1 to 1.5 mm wide, broadly ovate with a rounded apex. There are five stamens with short filaments and yellow anthers. The pistil has a superior ovary with a slender style about 3 to 4 mm long, ending in a small, bifid stigma. The fruit develops from August through October, maturing into small, globose berries approximately 6 to 8 mm in diameter, dark blue to black when ripe. Woodbine is native to South Dakota, commonly found climbing on trees, fence lines, and rocky bluffs in woodland edges and riparian zones throughout the state.

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  Vitaceae : Vitis riparia

  R. Neil Reese

  Vitis riparia is a perennial viny shrub with stem growing to 25 m in length. The young branches are green to a dull reddish brown and the older stems are woody with exfoliating bark. The simple, alternate leaves have smooth petioles up to 8 cm long. The blades are 7-20 cm long and nearly as wide, shallowly to deeply palmately lobed. Leaves on fertile branches usually have 3 major lobes with a broad gaps between the 2 basal lobes. The leaves on vegetative branches are more evenly divided. The margins are hairy and sharply toothed. The inflorescence consist of pyramidal panicles 4-12 cm long, opposite the leaves of this year's new branches. The plants are monoecious, separate male and female flowers are typically on the same plant, mixed in a cluster or separate, tiny with 5 green to yellowish petals that drop without expanding. The male flowers have 5 long, erect to ascending stamens. The female flowers have a short style and 5 short sterile contorted stamens. The fruit are purple black berries, 7-11 mm in diameter. Riverbank grapes bloom in May and June with fruit ripening in July through September. They are found along streams, fence rows, in woodlands and ravines throughout South Dakota.