Oaks of the World

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  Quercus wislizeni
Author A.DC 1864 Prodr. 16(2): 67
Synonyms agrifolia Newb. not Née
wislizeni f. extima Jeps. 1909
Local names Interior live oak; Sierra live oak;
Range California; Mexico; 300 - 1900 m; introduced in Europe in 1874;
Growth habit usually a shrub, but may reach 20 m, with trunk to 1.5 cm in diameter; numerous branches; broad open crown;
Leaves 2.5-5 x 1.2-3 cm; evergreen; leathery; flat (i.e. not rolled under), elliptic or oval lanceolate; apex more or less pointed; base obtuse, or sometimes cordate; margin entire or with small, awn-shaped teeth (to 16); both sides hairless; dark lustrous green above; yellowish green beneath; petiole 3-20 mm long, hairless or weakly pubescent;
Flowers male flowers in March-April, on 3-6 cm long catkins;
Fruits acorn 2-4 cm long, 0.8-1.4 cm wide; narrowly ovoid and gradually tapered at apex; hairless; sessile; both sides of cup slightly pubescent; cup enclosing 1/3 to 1/2 (sometimes 2/3) of nut, with flat, pointed scales free at their tip.

Bark, twigs and

bark blackish, deeply fissured, with scaly ridges; twigs brown, hairless or slightly pubescent, stiff, 1.5-3 mm in diameter; terminal bud reddish brown, ovoid, 3-9 mm long, hairless or with some hairs near apex;
Hardiness zone, habitat hardy; occurs on arid slopes; all types of soils; slow-growing;
Miscellaneous -- A. Camus : n° 298;
-- Sub-genus Quercus, section Lobatae, Series Agrifoliae;
-- Discovered by Adolf Wislizenus (1810-1889) = physician of St Louis, of German origin, botanist and friend of G. Engelmann;
-- Related to
Q.kelloggii and to Q.agrifolia (with which it forms hybrids)
-- Resembles Q.parvula, but the latter has stalked acorns and dull upper surface of leaves; Q.parvula deserves a species rank;

Subspecies and

--- var. frutescens Engelm. 1878 Trans. Acad. Sci. St. Louis 3: 396
= Q. wislizeni subsp frutescens (Engelm.) E.Murray 1983
shrub 2-4 m tall, multiple trunks, with smaller leaves (3.8 cm max.), oval, shiny green on both sides;
South California, Mexico (Baja Califofornia del Norte).
For Keuter & Manos 2017, the North-South variations of Q. wislizeni are insufficient to justify the taxonomic rank of variety.

--- Q.parvula Greene 1887 : see this word

--- Q.x morehus = kelloggii x wislizeni (= "Oracle Oak") : see this word