Quercus rubra L., Fagaceae

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Common name: Northern red oak.

Voucher: Kostadinov 107, (URV)

Brief description: Subgenus Erythrobalanus, red and black oaks.  A large monoecious tree to 50 m, the bark having broad, shallow furrows between flat, gray stripes (ridges); the inner bark is reddish to red-brown, the twigs are glabrous and dark reddish-brown. Leaves are simple, alternate, pinnately veined,  pinnately 7-11 lobed with pointed and relatively shallow lobes, which are broadest at base. The foliage is dull green and glabrous, except often for hairs in the axils of the veins beneath; the margins have bristle-tipped teeth. Flowers are unisexual, the staminate in slender catkins, the pistillate solitary or in small spikes. Fruits are a nut (acorn), partly enclosed by the persistent involucre -- the acorn cup. The acorn cup is shallow and saucer-shaped, with a ring of hairs inside. The acorns mature at the end of the second season and sprout at the beginning of the third. 

Campus data: Moderately frequent everywhere in the wild, not cultivated.