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.
Western Hemisphere and Eurasia.
Genera 7, species 59 (2 genera, 17 species in the flora).
The fruit in Juglandaceae superficially resembles a drupe, with a hard "stone" surrounded by a soft, often fleshy husk. The husk, however, is not part of the fruit wall (it develops from the involucre and calyx), and the fruit is actually a nut (T. S. Elias 1972; W. E. Manning 1978).
The morphology and classification of the family were discussed by W. E. Manning (1978). The female inflorescences and fruits show considerable variation in Latin American and Eurasian taxa.
|1||Branchlets with solid and homogeneous pith; distal leaflets largest; staminate catkins in sessile or pendunculate fascicles, stamens 3-10(-15) per flower; fruits with husks completely or partially dehiscent, nuts smooth, verrucose, or rugulose.||Carya|
|1||Branchlets with chambered pith; leaflets uniform in size or median leaflets largest; staminate catkins sessile, solitary, stamens 7-50 per flower; fruits with husks indehiscent, nuts grooved, ridged, furrowed, or smooth.||Juglans|