|Common name: Willow-oak.
Voucher: Kostadinov 064, (URV)
Brief description: Subgenus Erythrobalanus, red and black oaks. A monoecious tree to 25 m with glabrous twigs. Leaves are oblong-linear to lanceolate or oblanceolate, simple, alternate, entire, bristle-tipped, the margins entire. The foliage is shiny green above, paler beneath, and glabrous except for some stellate hairs on the vein axils beneath. 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 shallowly saucer-shaped and pubescent. The acorns mature at the end of the second season and sprout at the beginning of the third.
Campus data: Very frequently cultivated and quite frequent in the wild as well. Mature trees are usually among the largest on campus.