||Common name: Pin-oak.
Voucher: Kostadinov 110, (URV)
Brief description: Subgenus Erythrobalanus, red and black oaks. A monoecious tree to 30 m with smooth bark and glabrous twigs at maturity. Leaves are simple, alternate, pinnately veined, deeply pinnately 2-3 lobed with pointed lobes, widened distally. The tips of the lobes are perpendicular to the midvein. The foliage is shining and glabrous, except often for stellate hairs in the axils of the veins beneath; the margins have bristle-tipped teeth or small secondary lobes. 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 saucer-shaped with very small scales. The acorns mature at the end of the second season and sprout at the beginning of the third.
Campus data: Very rare on campus. One individual encountered.