Quercus × streimii Heuffel

from north Spain to Romania and Sweden;

tall tree;

5-10 x 3.5-7 cm, deciduous; lustrous and glabrous above, or with some traces of the original stellate pubescence; at first tomentose beneath with long simple hairs mixed with short stipitate fasciculate hairs and stellate others, becoming glabrous except along midrib; base asymmetrical or truncate; sinuate-lobed, lobes lobulate; 5-8 vein pairs, usually with intercallary veins; petiole ca. 0.7-1.6 cm;

acorn often avorted, on 5-7 mm tomentose peduncle; cup enclosing almost all the nut, with dark grey, pubescent scales; stylopodium pubescent; stigmas divergent, with wide obtuse tip;

— In Spain, the taxon named Q.x costae C. Vicioso is treated as a hybrid between Q.cerrioides (or Q. pubescens ) and Q.petraea subsp huguetiana ; but for Rivas-Martinez & Saenz, it is the hybrid between Q. petraea and Q. pubescens subsp subpyrenaica ; for the recent Spanish authors (F.M.Vazquez & al.), according to C. Vicioso, this taxon is: Q. cerrioides X Q. petraea subsp huguetiana ; 7-10 vein pairs, without sinusal veins; leaves glabrous above, pubescent underneath at first and becoming glabrous except on vein axils; lobes short and often mucronate; cup with greyish pubescent scales, the lower scales being convex; Spain (Cataluña).