Oaks of the World

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  Quercus canbyi
Author Trel. 1924
Synonyms alamarensis C.H.Mull. 1942
graciliformis C.H.Mull 1934
graciliformis f. parvilobata (C.H.Mull.) C.H.Mull. 1940
graciliformis var. parvilobata C.H.Mull. 1934
graciliramis C.H.Mull. 1936 (A.Camus n° 393)
karwinskii Trel. 1924
Local names chisos oak; slender oak; canby oak; graceful oak;
Range Mexico (Nuevo Leon, Tamaulipas); Texas (Chisos Mountains ) ; from 0 to 2100 m in rocky canyons ; restricted area;
Growth habit 4-15 m tall, with trunk 20-50 cm in diameter; long flexible branches somewhat drooping;
Leaves 7.5-10 x 2-3 cm; semi-evergreen or lately deciduous; thick, leathery; lanceolate to narrowly elliptic; apex pointed, attenuate; base rounded or cuneate; margin thick, revolute, with 4 pairs of shallow bristle-tipped dentate lobes, or sometimes entire; shiny green, hairless above; dull, reddish-brown beneath with sometimes axil tufts; 4-8 vein pairs; petiole hairless, slender, flexible, 1-2 cm long;
Flowers April-May; male catkins 3-5 cm long; pistillate ones 0.5-1 cm long, 1 or 2-flowered;
Fruits acorn 1.5 cm, narrow; stalkless; singly or paired; cup very shallow covering 1/4 or 1/3 of nut; maturing in 1 or 2 years;

Bark, twigs and
buds

bark brown green, smooth, becoming dark grey, warty, sulcate; twig red brown, shiny, thin (1-2 mm in diameter), soon glabrous, with light lenticels; terminal bud red brown, ovoid, 1.5-5 mm, shortly ciliate;
Hardiness zone, habitat zone 7-8 ; prefers dry, rocky soils;
Miscellaneous -- A. Camus : n° 384;
-- Sub-genus Quercus, section Lobatae, sub-section Acutifoliae;
-- Threatened (IUCN Red List Category : CR)
Subspecies and
varieties 		--- Q.canbyi has been described as a variety of Q.graciliformis in the south of its range (North Mexico), and differs from the type in having acorns maturing in 1 year, less lobes (4 pairs instead of 5...), and a shallower cup. In fact, it seems that it is nothing but a geographical form...For today's Mexican Authors (Silvia Romero Rangel, 2006), the accepted name is Q.canbyi, and Q.graciliformis is the synonym...

--- Q.alamarensis : for today's Mexican Authors (Susana Valencia-Avalos, 2004), this taxon described by Muller is doubfull, maybe a hybrid or a morphological, isolated variation...

--- Q.langtry (Langtry Oak) ; first considered as synonymous for Q.gravesii in 1850, is currently defined as a member of the graciliformis-canbyi group; discovered near Langtry (Texas), it bears 2 years maturing acorns and a greater number of lobes (5-7 instead of 2-5); but more studies are necessary to precise the taxonomical place of this species; hardiness zone : 7;
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