The World Flora Online

Trees, rarely shrubs , deciduous, with gray or brownish bark. Terminal buds larger than lateral buds. Leaves alternate [or opposite], aromatic, usually odd-, rarely even-, pinnately compound; stipules absent; petiole present. Leaflets 3-23, margins serrate or entire. Inflorescences: staminate catkins solitary or fasciculate, pendulous, elongate, on reduced shoots arising on branches of previous year or at base of current year's growth; pistillate catkins solitary or few-flowered spikes [or many-flowered racemes]. Flowers unisexual, staminate and pistillate on same plants; bract 1, bracteoles (0-)2. Staminate flowers: calyx 2-6-lobed or absent; corolla absent; stamens 3-50; filaments very short or absent; anthers usually pubescent. Pistillate flowers: calyx 4-lobed or absent; corolla absent; ovary 1, inferior, usually 2-carpellate, 1-locular distally; ovule 1; stigmas 2, fleshy or plumose. Fruits large nuts [or samaras], nuts enclosed in dehiscent or indehiscent, fibrous-fleshy or hard involucres (husks), thus ± drupelike. Seeds 1; endosperm absent; cotyledons fleshy and oily, variously lobed.

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Trees or rarely shrubs, deciduous, semievergreen, or evergreen, monoecious or rarely dioecious; bark tight (or exfoliating). Branchlets with solid or chambered pith. Terminal buds subglobose or ovoid to oblong, naked or with scales. Stipules absent. Leaves alternate (or opposite), odd- or even-pinnate, sometimes trifoliolate, rarely simple; leaflets with glandular, peltate scales, often resinous and aromatic, particularly conspicuous abaxially on young leaves and twigs, margin serrate or rarely entire. Inflorescences pendulous or sometimes erect, lateral or terminal, on reduced shoots arising on branchlets of previous year (old growth) or on current year’s growth (new growth), of several types: androgynous panicle with male, lateral spikes and female, central spike; androgynous panicle with male, mainly lateral spikes and female, central spike male at apex; cluster of male spikes and solitary female spike; or solitary male and female spikes. Flowers unisexual, anemophilous, rarely entomophilous. Male flowers subtended by an entire or 3-lobed bract; bracteoles 2 or absent; sepals 0-4, adnate to receptacle when present; stamens 3-40(-100), inserted on receptacle; filaments short to nearly absent, free or united at base; anthers glabrous or pubescent, 2-loculed, dehiscing longitudinally. Female flowers with an entire or 3-lobed bracts; bracteoles 2 or 3 (or absent); sepals 0-4, adnate to ovary, free at apex; gynoecium of 2 carpels united into an inferior ovary, 1-loculed, but at base 2-4(-8)-loculed; style 1, short or elongate, rarely absent; stigmas 2, carinal or commissural, sometimes 4-lobed, plumose or fleshy; ovule 1, orthotropous. Fruiting spike elongate, and pendulous or short and erect, rarely conelike. Fruit a drupelike nut, 2-4(-8)-chambered at base, with a dehiscent or indehiscent husk, or a 2- or 3-winged or disc-winged nutlet. Seed solitary, without endosperm. Cotyledons 4-lobed, much contorted. Germination hypogeal or epigeal. 2n = (28), 32, (64).

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Fls tiny, unisexual, borne in unisexual (seldom bisexual) catkins, the bracts, bractlets, and tepals variously connate and adnate and subject to diverse morphological interpretations; staminate catkins commonly (including our genera) elongate, drooping, borne on the twigs of the previous year, or at the base of the current year’s growth; staminate fls solitary in the axils of the bracts of the catkin, each with usually 4 tepals adnate to the 2 bractlets, with which they form a common structure, or the tepals (or both tepals and bractlets) obsolete; stamens 2–many; filaments short; pistillate fls mostly in short, few-fld catkins terminating the twigs of the season, or solitary and terminal, each fl subtended by a variously developed set of ± connate bracteoles and a single primary bract, these collectively often forming a minute, perianth-like involucre; ovary inferior, with 1–4 calyx-teeth toward the summit (or the calyx-teeth obsolete, as in Carya), mostly bilocular (or 4-locular by the intrusion of "false" partitions) below, unilocular above, the partition not reaching the top of the cavity; styles 2, distinct or basally connate, often with plumose stigma; ovule solitary, erect, orthotropous, borne at the summit of the partition; fr a rather large, sometimes samaroid nut, or ± drupe-like, the softer, fibrous husk (representing the ripened involucre) sometimes splitting to release the hard nut; embryo large, dicotyledonous; endosperm none; aromatic, anemophilous trees or shrubs with mostly alternate, pinnately compound, exstipulate lvs (ours deciduous) that are provided with small, resinous, peltate, basally embedded gland- scales. 7–8/60.

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SELECTED REFERENCES

Elias, T. S. 1972. The genera of Juglandaceae in the southeastern United States. J. Arnold Arbor. 53: 26-51. Manchester, S. R. 1987. The fossil history of the Juglandaceae. Monogr. Syst. Bot. Missouri Bot. Gard. 21: 1-137. Manning, W. E. 1978. The classification within the Juglandaceae. Ann. Missouri Bot. Gard. 65: 1058-1087. Stone, D. E. 1993. Juglandaceae. In: K. Kubitzki et al., eds. 1990+. The Families and Genera of Vascular Plants. 2 +vols. Berlin etc. Vol. 2, pp. 348-359.

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