Quercus bidoupensis Binh & Ngoc

Vietnam (Bidoup-Nui Ba National Park); 1700 m;

tree reaching 8 m hight;

(7-)10-13 cm x 2.4-5; oblong-lanceolate; coriaceous but thin; dry leaves blackish-brown adaxially, pale brown under; both sides glabrous; apex acuminate; base cuneate; margin undulate, distinctly serrate in apical 1/2; midrib impressed above, prominent beneath, as for the 10-13 pairs of secondary veins which are at an angle of 45-50° from midrib; tertiary veins visible on both surfaces; petiole 1.3-2 cm long, hairless;

acorn ovoid, 2.2 cm long x 1.4 cm wide, blackish, hairless, acute at apex, with convex basal scar 0.9 cm in diameter; cup obconical enclosing 1/3 of the nut, 1.3-1.5 cm high, 1.3-1.7 cm in diameter, bracts arranged in 5-6 entire rings;

– Sub-genus Cerris, section Cyclobalanopsis; – Belongs to the “ Quercus langbianensis Complex”. – Threatened (IUCN Red List Category : CR) – Similar to Q. langbianensis sensu stricto in leaf shape, the number of secondary veins and basal scar of the nut convex, but differs in having bud oblong to ellipsoid (vs globose to broadly oval), undulate and serrate leaf margin along the apical half (vs apical 1/3), obconical cupule (vs cup-shaped), bracts arranged in 5-6 rings (vs 6-9), and nut ovoid (vs obovoid to ellipsoid).