northern pin oak Fagaceae Quercus ellipsoidalis

Leaf:Alternate, simple, 3 to 6 inches long, oval in shape with very deep sinuses and bristle-tipped lobes, somewhat shiny green above, paler and generally hairless below but may have tufts in vein axils.
Flower:Species is monoecious; males are borne on slender yellow-green catkins; females are borne on very short axilliary spikes, both appear with the leaves in spring.
Fruit:Acorns are 1/2 to 1 inch long, elliptical to almost round; the cap covering 1/2 of the nut, cap scales are pubescent, scales on edges of cap generally loose; the tip of the acorn lacks concentric rings; maturing in two years and ripening in the fall.
Twig:Red-brown with multiple terminal buds; buds reddish brown, pointed, slightly angled, mostly hairless scales but terminal scales may bear some frosty pubescence.
Bark:On young trees, gray-brown, with smooth streaks; later becoming darker and developing irregular broad ridges and narrow furrows especially near the base; inner bark orangish.
Form:A small to medium-sized tree reaching up to 70 feet tall with generally poor form, irregular crown, and many dead branches. Photos graciously provided by Arne Myrabo.

leaf flower fruit twig bark form map