Oaks of the World

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  Quercus percoriacea
Author Soepadmo 1966 Gard. Bull. Singapore 21: 382
Synonyms
Local names
Range Borneo (north Sarawak); to 1200 m;
Growth habit tall tree to 30 m.,  with trunk to 0.5 m in diameter;
Leaves 10-18 cm x 4-8; thick, strongly coriaceous; oval or elliptic; apex long acuminate; base rounded; margin entire, plane, undulate in the lower half, remotely crenate dentate at apical 1/2; glabrous and shining above; glaucous beneath from waxy coat and small stellate hairs, glabrescent; 10-12 vein pairs, prominent beneath, impressed above, parallel, forming an angle of 40-60° with the midvein; petiole 2-3.5 cm long, slightly grooved adaxially, glabrous;
Flowers male catkins 5-6 cm long, many-flowered, densely stellate tomentose; male flowers 3-4 together along rachis, perianth 5-6-lobed, 5-6 stamens; female inflorescences 1 cm with 2-4 flowers, tomentose; female flowers with perianth 4-5-lobed, hairy, ovary conical, 3-4 styles;
Fruits acorn 2 cm in diameter, ovoid to globose, apex depressed, with basal scar convex; cupule rather flat, covering 1/6 to 1/5 of nut, with 6-8 denticulate or not rings;  from June to July;

Bark, twigs and
buds

bark smooth, grey; twig grey, glabrescent, with lenticels; terminal bud ovoid to subglobose, 3 mm long, densely tomentose;
Hardiness zone, habitat primary "kerangas" (heath) forests on plateau sands; not hardy;
Miscellaneous -- Sub-genus Cerris, Section Cyclobalanopsis; 
-- Section Oidocarpa, sub-section Niveae (Menitsky).
-- Closely related to Q.nivea (if not identical ?);
-- Threatened (IUCN Red List Category : EN).

Subspecies and
varieties
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