Quercus langbianensis
Quercus langbianensis is the accepted name of an uncommon oak tree species in the Asian sub-genus of "Cyclobalanopsis" in the family Fagaceae. These differ from other "Quercus" subgenera in that they have acorns with distinctive cups: usually with substantial rings, made-up of scales that have grown together. This species can be found in sub-tropical and tropical seasonal forests of Cambodia, China (mostly Yunnan) and Vietnam. Description. "Quercus langbianensis" is an evergreen tree that reaches a height of up to 15 m. The bark is rough, with spots. The branches are brown and tomentose when young , less hairy with age. The leaves measure 70-140 (up to 170) x 25–40 mm, elliptical-lanceolate to oblanceolate, leathery and glabrous on both sides, with margins having numerous small teeth that are obtuse, wavy near the apex: which is acuminate to slightly caudate; petioles are 15–20 mm and hairless. The acorns are sub-globose approximately 17–20 mm, covered with fine silky hair (sericeous), pale brown and ripening by September; scars are approximately 10 mm in diameter and convex. Their styles are persistent about 2 mm in diameter. Superficially, the cups are bowl-shaped, 8 x 20–25 mm approximately, enclosing  1/2 or 2/3 of the acorn. Outside and inside the reddish, tomentose acorn has a wall about 3 mm thick. The bracts are formed by 5 to 7 rings, with whole margins.