Oaks of the World

North-East Vietnam : Trung Khanh District, Cao Vit Gibbon Conservation Area, Cao Bang Province; 760 m;

9-12.5 cm X 2.5-5.8; evergreen; leathery; ovale or elliptic-ovate; apex acute acuminate; base rouded or slightly cordate; margin serrate in 2/3 to 4/5 apically; adaxially hairless except some stellate hairs near base; abaxially glabrescent or soon glabrous except some persistant hairs at axils; fruit-bearing twigs have glabrous leaves; 8-10 vein pairs, at an angle of 50-60° with the midrib, raised on both faces, as for the midrib; petiole 1.8-2.4 cm long, at first yellowish pubescent, then glabrescent.

acorn cylindrical, 1-1.5 cm long X 1-1.2 wide, with apex truncate or slightly depressed; stylopodium 2 mm lon; solitary or paired, on a 1-1.5 cm long stalk; sessile; cup bowl-shaped, 8-10 mm high X 12-14 mm wide; cupscales with blackish, acuminate apex, pubescent both sides; acorn enclosed 1/3 or 1/2 by cup; basal scar 5-6 mm in diameter;

bark pale grey, with deep vertical furrows; young twig with stellate, appressed, yellowish-brown hairs, then glabrescent; some lenticels; bud broadly ovoid, 3-4 mm long X 2-3 mm wide;

-- Sub-genus Cerris, section Ilex
-- Very rare (2 trees known !), strongly threatened of extinction (IUCN Red List Category : CR)

-- Possible confusion with Q. marlipoensis and Q. engleriana (both from China), but Q. marlipoensis has larger leaves (12-22 cm x 6-11) with more lateral veins (16-20) and cupscales ovate; Q. engleriana has smaller cups (8.5-10 cm in diameter), acorns ovoid with pointed apex, cups bearing a smaller number of scales, scales ovate-lancéolate, buds narrow, young twigs yellowish-grey tomentose, infrutescences with more acorns (to 10).