Quercus phellos L. Willow oak. Family Fagaceae. ITIS Taxonomic Serial Number 19282. USDA PLANTS Symbol QUPH. TROPICOS # 13100284.
Images Branchlet with leaves. Individual leaves. Branchlet with buds. Close-up of buds. Herbarium sheet 1. Herbarium sheet 2. Herbarium sheet 3.
Plant habit and life style. Plants Angiosperms, monoecious, (15)2030(40) m tall.
Stems. Pith continuous. Young twigs (1-year-old or less) red or reddish-brown, 12 mm wide, glabrous. Twigs (24 years old) glabrous. Leaf scars half-round, bundle scars numerous, stipule scars inconspicuous, stipule scars not circumferential. Bark of mature trunks furrowed or ridged.
Buds. Buds axillary or terminal, bud clusters at ends of twigs present, brown or reddish-brown, 24 mm long, ovoid, sharp, glabrous, bud scales imbricate.
Leaves. Leaves deciduous, simple, petiolate or nearly sessile, alternate or spiral, (4)512(13) cm long, (0.6)12.5(3) cm wide, elliptic or falcate or lanceolate or linear or oblanceloate or oblong, leaf margins entire, leaf margins plane or revolute, leaf apices acute or apiculate, leaf bases cuneate or rounded. Leaf upper surface green, glabrous. Leaf lower surface green, glabrous or glabrate or pubescent or with tufts in vein axils, stellate or tomentose. Leaf venation pinnate. Petioles 0.20.4(0.6) cm long, glabrous or glabrate. Stipules present, caducous, not circumferential.
Flowers. Flowering February or March or April or May. Inflorescences axillary, catkins or flowers solitary or spikes, flowers sessile. Flowers unisexual, epigynous. Perianth. Calyx radially symmetric, synsepalous. Sepals 46 per flower, yellow, sepal apices acute, pubescent, hirsute, caducous. Corolla absent. Androecium. Stamens (2)6(12) per flower, separate. Gynoecium. Ovaries inferior, pistils 1 per flower. Gynoecium syncarpous, 3 carpels per flower, styles 3 per pistil, placentation axile. Other floral features. Hypanthia present, involucres present.
Fruits. Fruits accessory fruits or acorns or nuts, 11.2(1.5) cm long, brown, fruit maturation 2 years.
Habitat. Habitat bottomland forests or disturbed and weedy areas or dry-mesic upland forests or mesic upland forests or mixed forest edges or suburban plantings.
Special Diagnostic Characters. Staminate flowers in pendent catkins, pistillate flowers solitary or in few- to many-flowered spikes; pistillate flowers enclosed by a scaly involucre which develops into the acorn cup.
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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