Pin oak

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Pin oak

Pin oak bark

Pin oak buds

Pin oak acorn

Pin oak leaves

Pin oak buds

Pin oak acorn

Pin oak staminate flowers

Pin oak

Pin oak buds

Pin oak acorn

Pin oak staminate flowers

Pin oak leaf

Pin oak

Pin oak pistillate flowers

Pin oak staminate flowers

Morphology

Trunk

Straight, diameter 1-2 feet; crown pyramidal or oblong; lower branches drooping, middle branches nearly horizontal, upper branches ascending; bark thick, grayish-brown, smooth or with broad, shallow furrows, ridges flat-topped.

Twigs

Slender, stiff, pin-like, initially dark red, woolly, becoming reddish-brown to grayish-brown, glabrous, shiny; leaf scars half-round; bundle scars 10 or more; terminal bud about 1/8 inch long; lateral buds clustered at tip of twig, egg-shaped or conical, 1/8 to 1/6 inch long, pointed, reddish-brown, glabrous or with few hairs at tip.

Leaves

Alternate, simple, deciduous, leathery, egg-shaped in outline, 2 to 6.4 inches long, 2 to 4.8 inches wide; lobes 5-7, slender, few-toothed, usually tapering at right angles to midrib; apex sometimes expanded, bristle-tipped; sinuses deep, often approaching midrib, wide, rounded; upper surface dark green, glabrous, shiny; lower surface paler, hairs in vein axils; stalk .8 to 2.4 inches long, slender, glabrous; base wedge-shaped to broadly blunt or cut straight across; stipules linear or oblanceolate, 1/4 inch long; unfolding leaves reddish-brown, hairy; in autumn, initially turn scarlet, become brown, often persist on tree during winter.

Flowers

With the leaves, monoecious; staminate catkins 2 to 3 inches long, drooping, loosely-flowered; flowers small, brownish, hairy, sessile or with short pubescent stalk; calyx bell-shaped, 3-5-lobed, tip acute, ciliate; stamens 4-6; anthers yellow; pistillate flowers at base of leaves on new growth, small, spherical, green; stalks short; involucre scales woolly; styles 3, curved outward, green with pink tip; stigmas 3-lobed, flattened, recurved, red.

Fruit

Autumn of second year; acorn, sessile or short-stalked; cup saucer-shaped, shallow, 2/5 to 3/4 inch wide, 1/8 to 1/4 inch high, enclosing only base of nut; cup scales triangular, reddish-brown, closely appressed, pubescent or glabrous, margins dark; nut dome-shaped to egg-shaped, 1/2 to 3/5 inch long, 2/5 to 3/5 inch in diameter, often ridged, light brown, base flattened; kernel bitter.

Ecology

Habitat

River bottoms on rich moist soil but also may be found on rocky wooded hillsides on poorly drained clay soils.

Distribution

East 1/3 of Kansas

Practical Information

Uses

Native American steeped the inner bark and took the liquid for intestinal pains. Squirrels, blue jays, and wood ducks eat the nuts. Planted as a street and residence ornamental tree. The wood is used for interior finishes, railroad ties, and to make pins and small pegs for fasteners.

Additional Notes