Acer negundo L. Box elder, ash leaved maple, boxelder, Texas box elder, eastern box elder. Synonyms Acer negundo var. texanum Pax, Negundo aceroides (L.) Moench, Negundo negundo (L.) Karst. Family Sapindaceae. ITIS Taxonomic Serial Number 28749. USDA PLANTS Symbol ACNE2. TROPICOS # 00200001.
Images Branchlet with leaves. Individual leaf 1. Individual leaf 2. Branchlet with buds. Close-up of buds. Close-up of fruits. Herbarium sheet 1. Herbarium sheet 2.
Brief Description: A small to medium-sized, deciduous tree usually 1520 m. (5065 ft.) tall when fully grown. Bark of mature trunks is furrowed and ridged, sometimes with small plates, becoming deeply furrowed with age. Young twigs are typically green. Leaves are opposite and pinnately compound, most often with 35 (occasionally 79) leaflets. Leaflet margins usually have scattered, coarse teeth or small lobes, especially on the portion toward the leaf tip, but may also be entire. Male and female flowers occur on separate trees. As with other maples, fruits consist of two, winged samaras that split apart when mature and travel on the breeze as they spin to the ground.
Plant habit and life style. Plants Angiosperms, dioecious, (5)1520(30) m tall.
Stems. Pith continuous. Young twigs (1-year-old or less) green or red, glabrous or pubescent, puberulent or tomentose. Twigs (24 years old) glabrous or pubescent. Leaf scars U-shaped or V-shaped, bundle scars 3 per leaf scar, stipule scars absent. Bark of mature trunks furrowed or plated or ridged.
Buds. Buds axillary or terminal, gray, 38 mm long, ovoid, blunt or sharp, pubescent, ciliate or tomentose, bud scales imbricate.
Leaves. Leaves deciduous, compound, trifoliolate or once pinnately compound, petiolate, opposite or decussate, 1230 cm long, 1121 cm wide. Leaf upper surface green, glabrous or glabrate. Leaf lower surface green, glabrate or pubescent or with tufts in vein axils, pilose or tomentose or villous. Leaflets nearly sessile or sessile, 35(9) per leaf, (5)610(12) cm long, (3)47(9) cm wide, elliptic or lanceolate or oblong or obovate or oval or ovate or rhombic, leaflet margins entire or serrate, unlobed or shallowly lobed or moderately lobed, pinnately lobed, leaflet apices acuminate or acute, leaflet bases cordate or cuneate or oblique or obtuse or rounded, leaflet venation pinnate, terminal leaflet present (odd-pinnate). Petioles 58 cm long, glabrous or glabrate or pubescent. Rachises glabrous or glabrate or pubescent. Stipules present or absent, caducous.
Flowers. Flowering March or April. Inflorescences axillary, racemes or simple umbels, flowers stalked. Flowers unisexual or pistillate or staminate. Perianth. Calyx radially symmetric, aposepalous or synsepalous. Sepals (4)5(12) per flower, calyx tubes 1.5 mm long, 0.51 mm long, ascending, green or yellow-green. Corolla absent. Androecium. Stamens 46 per flower, separate, anthers 24 mm long. Gynoecium. Ovaries superior, pistils 1 per flower. Gynoecium syncarpous, 2 carpels per flower, styles 2 per pistil, styles 00.5 mm long, stigmas 46 mm long, placentation axile.
Fruits. Fruits mericarps or samaras or schizocarps, (2.5)34.5(5) cm long, yellow or yellow-green, fruit maturation 1 years.
Habitat. Habitat bottomland forests or disturbed and weedy areas or mesic upland forests or mixed forest edges.
Cite this publication as: ‘Stephen M. Seiberling, Alan S. Weakley, and Peter S. White (2005 onwards). Common Trees of the North Carolina Piedmont: Identification, Descriptions, Illustrations, and Glossary. Version: March 7, 2006. <http://www.ibiblio.org/openkey/intkey/>’.
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