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Jepson Interchange (more information)
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  • Up-to-date information about California vascular plants is available from the Jepson eFlora.

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. X macdonaldii Greene

MACDONALD OAK

Tree 5–15 m, deciduous; trunk bark scaly, grayish; twigs tomentose
Leaf 4–7 cm; petiole 3–10 mm; blade oblong to obovate, tip obtuse to rounded, margin 2–6(8)-lobed, lobes generally pointed, upper surface glabrous to sparsely hairy, green, ± shiny, lower surface densely appressed-stellate-hairy, ± pale green
Fruit maturing in 1 year; cup 10–20 mm wide, 6–10 mm deep, hemispheric, scales clearly tubercled, canescent; nut 20–35 mm, conic-oblong to ovoid, tip acute, shell glabrous inside
Ecology: Slopes, canyons, woodland
Elevation: < 600 m.
Bioregional distribution: Channel Islands (except San Clemente Island).Considered by Greene as sp. but derived from hybrids between Q. berberidifolia and Q. lobata ; perhaps other species involved; needs further study
Horticultural information: DRN, SUN: 5, 7, 8, 9, 10, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24.

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