The World Flora Online

Trees or rarely shrubs, monoecious, evergreen or deciduous. Stipules usually early deciduous. Leaves alternate, sometimes false-whorled in Cyclobalanopsis. Inflorescences unisexual or androgynous with female cupules at the base of an otherwise male inflorescence. Male inflorescences a pendulous head or erect or pendulous catkin, sometimes branched; flowers in dense cymules. Male flower: sepals 4-6(-9), scalelike, connate or distinct; petals absent; filaments filiform; anthers dorsifixed or versatile, opening by longitudinal slits; with or without a rudimentary pistil. Female inflorescences of 1-7 or more flowers subtended individually or collectively by a cupule formed from numerous fused bracts, arranged individually or in small groups along an axis or at base of an androgynous inflorescence or on a separate axis. Female flower: perianth 1-7 or more; pistil 1; ovary inferior, 3-6(-9)-loculed; style and carpels as many as locules; placentation axile; ovules 2 per locule. Fruit a nut. Seed usually solitary by abortion (but may be more than 1 in Castanea, Castanopsis, Fagus, and Formanodendron), without endosperm; embryo large.

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Trees or shrubs , evergreen or deciduous, shrubs sometimes rhizomatous. Winter buds sessile, with few to many imbricate scales (2 valvate scales enclosing imbricate scales in Castanea ); terminal bud present or absent. Leaves alternate, spirally arranged, simple; stipules deciduous (usually), distinct, scarious; petiole present. Leaf blade lobed or unlobed, pinnately veined, margins serrate, dentate, or entire; surfaces usually pubescent, at least when young, sometimes with scales. Inflorescences unisexual or androgynous catkins; staminate and androgynous catkins spicate or capitate, rigid, flexible, or lax, consisting of few- to many-flowered clusters, bracts present or absent; pistillate catkins rigid or flexible, with 1-several spicately arranged, rarely solitary, terminal cupules bearing 1-3(-15 or more) pistillate flowers. Staminate flowers bracteate, bracts often caducous; sepals (3-)4-6(-8); stamens (3-)6-12(-18 or more); petals absent; anthers 2-locular, dehiscing by longitudinal slits, pollen sacs contiguous; pistillode often present and indurate, or vestigial as central tuft of trichomes. Pistillate flowers: calyx of 4-6 distinct or connate sepals; petals absent; pistil 1, 3(-6 or more)-carpellate; ovary inferior, locules as many as carpels; placentation axile; ovules pendulous, 2 in each locule, all but 1 in each pistil usually aborting; styles as many as carpels, distinct to base; stigmas dry; staminodes present or absent. Fruits nuts, sometimes winged, 1-seeded, subtended or enclosed individually or in groups of 2-3(-15) by scaly or spiny, multibracteate cupule; seed coat membranous; endosperm none; embryo straight, as long as seed; cotyledons fleshy, starchy or oily.

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Fls tiny, inconspicuous, unisexual (the plants monoecious) or some of them perfect; staminate fls borne in catkins or heads, with 4–7 (most commonly 6) minute, scale-like tepals, these distinct or connate below, or sometimes almost obsolete; stamens (4–)6–12(–40), on slender filaments; pistillate fls 1–7(–15) together at the base of the staminate catkins or from separate axils, individually or collectively subtended by an involucre that develops into a cupule; ovary inferior, of (2)3 or sometimes 6(7–12) carpels, with 3–7 minute tepals around the summit, or these obsolete; styles as many as the carpels; locules as many as the carpels, but the septa sometimes not reaching the summit of the ovarian cavity; ovules 2 in each locule, pendulous, anatropous; fr generally a nut with a stony to leathery pericarp, subtended at the base or more or less enclosed individually or collectively by an accrescent cupule or hull that appears to be composed of numerous, imbricate, concrescent bracts; seed solitary, with large, straight, dicotyledonous embryo and without endosperm; anemophilous or sometimes secondarily entomophilous trees or shrubs with alternate, simple, entire to deeply lobed, pinnately veined leaves and deciduous stipules. 6–8/800.

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SELECTED REFERENCES

Elias, T. S. 1971b. The genera of Fagaceae in the southeastern United States. J. Arnold Arbor. 52: 159-195. Fey, B. S. and P. K. Endress. 1983. Development and morphological interpretation of the cupule in Fagaceae. Flora 173: 451-468. Forman, L. L. 1966. On the evolution of cupules in the Fagaceae. Kew Bull. 18: 385-419. Hjelmquist, H. 1948. Studies on the floral morphology and phylogeny of the Amentiferae. Bot. Not., Suppl. 2(1): 1-171. Nixon, K. C. and W. L. Crepet. 1989. Trigonobalanus (Fagaceae): Taxonomic status and phylogenetic relationships. Amer. J. Bot. 76: 828-841. Soepadmo, E. 1972. Fagaceae. In: C. G. G. J. Van Steenis, ed. 1950+. Flora Malesiana.... Series I. Spermatophyta. 11+ vols. in parts. Djakarta and Leiden. Vol. 7, part 2, pp. 265-403.

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