Jepson Flora Project: Jepson Interchange    

 
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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 acutidens Torr.

Shrub or small tree < 6(10) m, evergreen
Leaf 2–6 cm; petiole 3–7 mm; blade generally oblong to obovate, ± leathery, tip obtuse to short-toothed, margin wavy to irregularly toothed, teeth ± obtuse, upper surface shiny and green to dull and bluish green, lower surface ± densely puberulent, becoming glabrous, dull, pale green
Fruit: maturing in 1 year; cup 10–18 mm wide, 6–9 mm deep, bowl-shaped, scales ± tubercled; nut 20–25 mm, oblong to ovoid, tip ± obtuse, shell glabrous inside
Ecology: Slopes, chaparral, woodland
Elevation: < 1600 m.
Bioregional distribution: Peninsular Ranges. Hybrids, involving Q. cornelius-mulleri and Q. engelmannii , considered by Torrey as sp.

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