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.