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Shrub 1–3 m (var. parvula) or tree to 17 m (var. shrevei, var. tamalpaisensis). Leaves evergreen, 3–16 cm long, oblong, lanceolate or ovate, upper surface olive-green and glabrous, lower surface dull olive-green and glabrous, six to eight secondary veins on each side of the midrib, margins entire, rarely dentate, apex acute to acuminate; petiole 0.2–1 cm long. Cupule bowl-shaped, 1.2–1.5 × 0.6–1 cm, tomentose inside; scales flat, rather thin. Acorn barrel-shaped to ovoid with an abruptly tapered apex, 3–4.5 cm long. Flowering in late spring, fruiting the year after flowering (USA). Tucker 1993. Distribution USA: California. Var. parvula occurs on Santa Cruz Is. and in a few sites in Santa Barbara Co.; var. shrevei (C.H. Mull.) Nixon from the Santa Lucia Mts. north to the San Francisco Bay Area; var. tamalpaisensis S.K. Langer in the vicinity of Mt. Tamalpais. Habitat Woodland and chaparral in canyons and on slopes below 1000 m asl. USDA Hardiness Zone 8. Conservation status Endangered. Illustration NT745. Taxonomic note This species is often confused with Q. wislizeni A. DC. (Bean: B521) and was treated as a synonym of it by Nixon (1997). However, it can be distinguished by its larger leaves (3–16 cm vs. 2–5 cm long), distinctive leaf undersides (dull olive-green vs. shiny yellow-green) and acorns (abruptly tapered vs. gradually tapered). Quercus parvula is more typical of wetter areas in the coastal fog belt; in contrast, Q. wislizeni is typical of arid slopes in the interior. While hybrids of the two species do occur naturally (in the San Francisco Bay Area), the characters that distinguish the species do not change when they are grown together outside their native habitats, and interspecific hybridisation is not uncommon in oaks (Nixon 2002).
Quercus parvula is in cultivation in specialist oak collections, and has reached 3.6 m after 10 years of growth at the Hillier Gardens. A similarly sized specimen at Chevithorne Barton was fruiting heavily in August 2006, with clusters of acorns on the previous year’s shoots. The cupule almost entirely covers the acorn. The leaves are a glossy dark green, with sparse and irregular teeth. This is perhaps not a prepossessing tree, with evergreen foliage reminiscent of several Mexican species, but it is interesting as one of few Californian red oaks, and if judged by the limited sample seen, is vigorous and hardy in cultivation.