Common Trees of the North Carolina Piedmont

Stephen M. Seiberling, Alan S. Weakley, and Peter S. White

Albizia julibrissin Durazz. Mimosa, mimosa tree, silktree. Synonyms Albizzia julibrissin. Family Fabaceae. ITIS Taxonomic Serial Number 26449. USDA PLANTS Symbol ALJU. TROPICOS # 13025045.

Images • Branchlet with leaves. • Individual leaf. • Closed individual leaf. • Close-up of leaflets. • Branchlet with buds. • Close-up of buds. • Flowers. • Close-up of fruits. • Herbarium sheet 1. • Herbarium sheet 2. • Herbarium sheet 3. • Herbarium sheet 4.

Brief Description: A small, deciduous tree, typically 10–15 m (33–50 ft.) tall when mature. Bark is gray and smooth, often with scattered small bumps. Leaves are alternate and bipinnately compound, with many (commonly 250–1200 or more) leaflets per leaf. The leaves fold up at night. The main vein of each leaflet runs along its leading edge. Flowers are arranged in heads, each flower bearing relatively small, inconspicuous, green petals. However, long, bright pink or purple stamens protrude beyond the corolla, creating the colorful ‘powder puff’ appearance of the inflorescence. Fruits are flat pods (legumes), 8–20 cm long, which change from green to brown or black when mature. Mimosa is not native to the North Carolina Piedmont, having originated in tropical Asia. It has become widespread throughout the southern United States though, aggressively establishing itself in disturbed areas and roadsides.

Detailed Description:

Plant habit and life style. Plants Angiosperms, polygamous, (3–)10–15(–20) m tall.

Stems. Pith continuous. Young twigs (1-year-old or less) green, glabrous or glabrate. Twigs (2–4 years old) glabrous. Leaf scars heart-shaped or three-lobed, bundle scars 3 per leaf scar, stipule scars present, stipule scars not circumferential. Bark of mature trunks with conspicuous lenticels or smooth.

Buds. Buds axillary or superposed, brown or green, 1–2 mm long, globose or oblong, blunt, glabrous or glabrate or pubescent, bud scales imbricate or valvate.

Leaves. Leaves deciduous, compound, bipinnately compound, petiolate, alternate, 10–50 cm long. Leaf upper surface green, glabrous. Leaf lower surface green, glabrous or glabrate or pubescent. Leaflets sessile, (100–)250–1200(–1400) per leaf, 0.8–1.5 cm long, 0.3–0.5 cm wide, oblong, leaflet margins entire or ciliate, leaflet apices mucronate or obtuse or rounded, leaflet bases oblique or obtuse or rounded or truncate, leaflet venation palmate or pinnate, terminal leaflet present (odd-pinnate). Stipules present, caducous, not circumferential.

Flowers. Flowering April or May or June or July or August. Inflorescences axillary or terminal, heads or panicles or racemes, flowers sessile. Flowers bisexual or unisexual or staminate, hypogynous. Perianth. Calyx radially symmetric, synsepalous. Sepals 5 per flower, calyx tubes 1.5–3 mm long, green. Corolla radially symmetric, funnelform or salverform, sympetalous. Petals 5 per flower, corolla tubes 5–10 mm long, green. Androecium. Stamens 99 per flower, monadelphous, filaments 20–30 mm long. Gynoecium. Ovaries superior, pistils 1 per flower. Gynoecium monocarpous, 1 carpels per flower, styles 1 per pistil, placentation parietal.

Fruits. Fruits legumes, 8–20 cm long, black or brown, fruit maturation 1 years.

Habitat. Habitat bottomland forests or disturbed and weedy areas or mixed forest edges or suburban plantings.

Special Diagnostic Characters. Leaflets fold up at night; elongated pink or purplish stamens provide the predominant color of the flowers.

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. <>’.

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