Oaks of the World

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  Quercus canbyi
Author Trel. 1924 Mem. Natl. Acad. Sci. 20: 188 1924.
Diagnosis here

alamarensis C.H.Mull. 1936 Diagnosis here
canbyi f. ascendens Trel. 1924
canbyi f. attenuata C.H.Mull. 1936
canbyi f. concolor Trel. & C.H.Mull. 1936
canbyi f. berlandieri Trel. 1924
canbyi f. karwinskii (Trel.) C.H.Mull. 1936
canbyi f. pedunculata C.H.Mull. 1936
canbyi f. setacea C.H.Mull. 1936
canbyi f. subovatifolia C.H.Mull. 1936
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) Diagnosis here
karwinskii Trel. 1924

Local names chisos oak; slender oak; canby oak; graceful oak;
Range Mexico (Coahuila, 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 4-10 x 1-4 cm; semi-evergreen or lately deciduous; thick, subleathery; lanceolate, elliptic, sometimes oval; apex pointed, bristle-tipped; base acute, obtuse or rounded; margin thick, slightly revolute, with 5-6 pairs of bristle-tipped, short teeth (from base to apex, or only on the apical 3/4) with shallow sinuses; dark lustrous green above, hairless or sometimes with shorts stellate hairs, and glandular ones, mostly along veins; dull, yellowish-green beneath, glabrous or with axil tufts of fascicled hairs; 5-7 vein pairs, mostly straight, flat above, slightly raised beneath; epidermis slightly papillose ; petiole hairless, slender, flexible, 1-2 cm long;
Flowers April-May; male catkins pubescent, 3-9 cm long, with 20-30 flowers with 5-6 stamens and glabrous anthers; pistillate ones 0.5-1 cm long, 1 or 2-flowered;
Fruits acorn 1-1.5 cm, ovoid; peduncle 2-5 mm long; singly or to 2 together; cup covering 1/2 of nut, with nearly flat scales; maturing in 1 year from August to October;

Bark, twigs and

bark brown green, smooth, becoming dark grey, warty, sulcate; twig red brown, shiny, thin (1 mm in diameter), soon glabrous, with rare, inconspicuous lenticels; terminal bud red brown, ovoid to conical, 1.5-3 mm, shortly ciliate;
Hardiness zone, habitat hardy zone 7; prefers dry, rocky soils;
Miscellaneous -- A. Camus : n° 384;
-- Sub-genus Quercus, section Lobatae, Series Erythromexicanae, Group Acutifoliae;
-- Confusion is possible with Q. albocincta, which has ovate or elliptic leaves, more veins pairs, longer teeth, longer bristle-tips and longer petioles.
-- Resembles Q. affinis but this species has coriaceous leaves, petiols shorter, 2-4 (-5) pairs of teeth, and the acorn matures in 2 years;

Subspecies and
--- 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;