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General: Walnut family (Juglandaceae). Small to medium-sized native trees with stiff upright branches and a wide-spreading crown, the young twigs, stems, and leaflets have hairs sticky-oily to the touch; terminal buds 12-18 mm long; bark brownish-gray, thick, shallowly divided into smooth or scaly plates. Leaves are pinnately compound, the leaflets (7-) 11-17, ovate to lanceolate or oblong-lanceolate, ± symmetric, mostly 5-11cm long, with finely toothed margins, terminal leaflet present, the lower surfaces densely covered with stellate hairs. Flowers are unisexual, female (pistillate) and male (staminate), but on the same tree (the species monoecious), usually not opening simultaneously on any individual tree; male flowers in slender catkins 6-14 cm long, the female flowers in terminal clusters of 6-8 flowers each. Fruit is an oblong-ovoid nut 4-6(-8) cm long, single or in clusters of 2-5, with a hard, thick, deeply furrowed shell enclosed by a thick husk with a sticky-glandular surface. The nuts usually remain on the tree until after leaf fall. The common name refers to the mature nut kernels, which are sweet and oily, like butter.