Contemporary Circumscription Compared with A Utah Flora 4th ed.
Bio430
Fagaceae
No differences locally; Nothofagus (southern beeches of the Southern Hemisphere) are removed to their own family.
Key Features
Woody monoecious trees or shrubs with simple, alternate, minutely stipulate leaves; the tiny imperfect male flowers are in catkins or small heads, while the female flowers are in tiny cymes. The inferior ovary is mostly 3 carpellate, 3 locular, and with 2 ovules per locule; as in Betulaceae, all but one of the ovules aborts so that the fruit matures into a nut subtended or enclosed by an involucre of overlapping, sometimes spiny bracts (cupule).
California live oak
Castanea (chestnuts) - Nauvoo
Castanea dentata - fruit and male inflorescence (courtesy of Jim Hardin)
Quercus gambelii (scrub oak)
Young acorn with involucral bracts forming cupule
Section through an acorn, showing the involucral bracts (outermost), the pericarp, and the developing seed inside
Oak - male catkins
Oak- male catkins
Fagus (beech) - male inflorescence head and female cupule
Fagus - section through a young female cupule showing multiple nuts
Fagus - maturing female cupule
Fagus male inflorescences
Fagus cupule with nut inside
Fagus cupule with nut inside
Fagus (Beech) nut is three sided, from 3 fused carpels
Acorn in cupule (cupule = whorled, connate involucral bracts)
Acorn starting to germinate, with pericarp splitting along 3 lines (3 carpels)
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Acorn, mature, with 3 stigmatic lobes still apparent
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