FAGACEAE

OAK FAMILY

John M. Tucker

Shrub or tree, monoecious, deciduous or evergreen
Leaves simple, alternate, petioled; margin entire to lobed; stipules small, generally deciduous
Staminate inflorescence: catkin or stiff spike; flowers many
Pistillate inflorescence 1–few-flowered, generally above staminate inflorescence; involucre in fruit generally cup-like or lobed and bur-like, bracts many, generally overlapping, flat or cylindric
Staminate flower: sepals generally 5–6, minute; petals 0; stamens 4–12+
Pistillate flower: calyx generally 6-lobed, minute; petals 0; ovary inferior, style branches generally 3
Fruit: acorn (nut subtended by scaly, cup-like involucre) or 1–3 nuts subtended by spiny, bur-like involucre; nut maturing in 1–2 years
Seed generally 1
Genera in family: 7 genera, ± 900 species: generally n hemisphere. Wood of Quercus critical for pre-20th century ship-building, charcoal for metallurgy; some now supply wood (Fagus, Quercus ), cork (Q. suber ), food (Castanea , chestnut).

QUERCUS

OAK

Evergreen or deciduous
Leaf: stipules small, generally early deciduous
Staminate inflorescences: catkins, 1–several, slender, on proximal part of twig
Pistillate inflorescence axillary among upper leaves, short-stalked; flower generally 1
Staminate flower: calyx 4–6-lobed, minute; stamens 4–10
Pistillate flower: calyx minute, generally 6-lobed; ovary enclosed by involucre
Fruit: acorn, maturing in 1–2 years; nut enclosed by cup-like involucre with thin or tubercled scales
Chromosomes: 2n=24 for all reports
Species in genus: ± 600 species: n hemisphere, to n South America, India
Etymology: (Latin: ancient name for oak)
Many more hybrids have been named but are not included here. Reproduction of many species declining.

Native

Q. douglasii Hook. & Arn.

BLUE OAK

Tree 6–20 m, deciduous; trunk bark checkered into thin scales, grayish
Leaf 3–6(8) cm; petiole 3–9 mm; blade oblong to obovate, tip generally rounded, margin ± entire, wavy, or slightly lobed, upper surface dull, bluish green, lower surface puberulent, pale bluish green
Fruit maturing in 1 year; cup 12–20 mm wide, 6–10 mm deep, cup- to bowl-shaped, scales slightly tubercled; nut 20–35 mm, ovoid, tip pointed, shell glabrous inside
Ecology: Dry slopes, interior foothills, woodland
Elevation: < 1200 m.
Bioregional distribution: Inner North Coast Ranges, Cascade Range Foothills, Sierra Nevada Foothills, Tehachapi Mountain Area, n San Joaquin Valley, San Francisco Bay Area, Inner South Coast Ranges, Western Transverse Ranges (n slope). Hybridizes with Q. garryana, Q. john-tuckeri, Q. lobata.
Horticultural information: DRN, SUN: 1, 2, 3, 7, 8, 9, 11, 14, 15, 16, 18, 19, 20, 21, 22, 23, 24 &DRY: 4, 5, 6, 10, 17.