River birch

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River birch bark

River birch catkins

River birchpistillate flowers

River birch bud

River birch

River birch

River birch staminate flowers

River birch leaves

River birch leaf

River birch pistillate flowers

River birch staminate flowers

Morphology

Trunk

Erect; bark grayish brown, yellowish white, or reddish white, exfoliating in thin, papery flakes or sheets; wood tan, hard.

Twigs

Reddish brown to grayish brown, flexible, glabrous or sparsely pubescent, often with scattered resinous glands; leaf scars triangular; buds reddish gray, ovoid, .2 to .25 inch, apex acute, scales pubescent.

Leaves

Deciduous, alternate, simple; petiole .3 to .6 inch; blade rhombic-ovate to narrowly deltate, 1.6 to 3.6 inches long, 1.4 to 2.4 inches wide, base cuneate to truncate, margins coarsely 2-serrate, apex acute to acuminate, surfaces abaxially green, pubescent to velutinous, adaxially dark green, glabrous or sparsely pubescent.

Flowers

Inflorescences formed in previous season and exposed in winter, catkins; staminate: mostly terminal, 1-3, pendent, 2.8 to 3.6 inches long, .2 to .3 inch wide, many-flowered; pistillate: proximal to staminate, 1, erect, .8 to 1.2 inch long, .8 to 1.2 inch long, .2 to .3 inch wide, many-flowered, becoming cone-like but not woody in fruit, conic to globose, 1 to 2.4 inch long, .4 to 1 inch wide; peduncles .4 to 1.5 inch; unisexual, more or less radially symmetric; staminate: bracteate, each bract with 3 flowers; sepals 2-4, distinct, ovate, minute; petals absent; stamens 2; pistillate: bracteate, each bract with 3 flowers; perianth absent; pistil 1; styles 2; stigmas 2.

Fruit

May and June; samaras, reddish brown, broadly ovate, .1 to .14 long, .2 inch wide, glabrous, wings 2, broad; seed 1.

Ecology

Habitat

Floodplain forests and woodlands, stream banks, swamps.

Distribution

Southeast corner of Kansas; also planted widespread.

Additional Notes