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Dioecious shrubs or trees, often slender and flexuous, often from a sub-terranean caudex; branching alternate. Leaves mostly deciduous, alternate, simple, often narrow, mostly denticulate, the costa prominent with numerous lateral veins; petiole mostly present; stipules mostly present, deciduous or per-sistent, sometimes foliaceous; buds with an indurate, deciduous scale and a hyaline membranous covering. Inflorescences dense spikes or racemes (aments, catkins), terminal on axillary shoots, lax or erect, subtended by basal leafy bracts; pedicels short, elongating in fruit, subtended by a bracteole. Male flowers with 1-2 short glands above the bracteole or a disc, the stamens 2-8, the filaments free or basally united, sometimes pubescent, the anthers rotund, 2-thecate, longitudinally dehiscent; female flowers with short glands above the bracteole or surrounding the ovary, the ovary sessile or stalked, 1-loculed, the style short or elongate, the stigmas 2-4, short, digitate. Fruit a small, 2-4-valved capsule, the valves somewhat leathery, apically dehiscent and recurving; seeds numerous, lenticulate, long-pilose, the embryo erect with 2 large cotyledons and a short epicotyl, the endosperm nuclear.
Trees or shrubs deciduous, rarely evergreen (if shrubs, then erect, ascending procumbent, creeping, or cushion-shaped); pith terete. Branches terete. Terminal bud usually absent; budswith single scale. Leaves alternate, rarely subopposite or opposite; stipules small, free, deciduous or persistent, developed mainly on vigorous branchlets; petiole short; leaf bladevariously shaped, often long and narrow. Flowering precocious, coetaneous, or serotinous; catkins upright or spreading, rarely pendulous; bracts entire, persistent or caducous.Flowers entomophilous or anemophilous, each with 1 or 2 glands: 1 abaxial (dorsal) or absent and 1 adaxial (ventral), i.e., abaxial gland between bract and stipe, adaxial gland betweenstipe and rachis. Male flower: stamens 2-many; filaments free or partly to completely connate, usually exceeding bracts; anthers 2-loculed (rarely 4-loculed if filaments connate), openinglengthwise. Female flower: ovary 2-loculed, sessile or stipitate; style 1, short, slender, or absent, entire or 2-cleft; stigmas 1 or 2, lobed or entire. Capsule 2-valved. Seeds mostly green orgray-green, small, surrounded by fine hairs.
Dioecious trees or shrubs. Growth-mode in flushes. Leaves simple, spirally arranged, mostly elliptic to linear, often deciduous. Stipules mostly caducous, sometimes wanting. Catkins terminal, on short, caducous, axillary axes (bearing dwarfed leaves in Mal. spp.). Flowers about spirally arranged along the rhachis of the catkin, each subtended by a membranous, entire bract. Perianth absent. Disk variable in shape, often consisting of 2 median lobules, or only one adaxial (in extra-Mal. spp. rarely more in a whorl, or cupular). Stamens (1-)2-15, in Malaysian spp. free or nearly so; anthers dehiscing longitudinally. Ovary more or less stipitate, 1-celled, consisting of 2 carpels; style more or less distinct, lobed. Ovules several, anatropous, basal, inserted amidst a mass of gradually developing, 1-celled hairs on 2 marginal placentas in the lower part of the ovary; the hairs arising both from the funicle and surrounding tissue. Capsule 2-valved, valves recurving. Seeds small, pushed out together with the hairs, without endosperm; testa thin.
Trees or shrubs, sometimes prostrate and rooting at nodes; bark rough and fissured or smooth. Winter buds with 1 outer scale. Lvs usually alternate, rarely opposite, entire or shallowly toothed; petiole usually short; stipules sometimes 0 or inconspicuous, sometimes conspicuous, usually caducous, especially on strong vegetative shoots; lamina generally lanceolate or elliptic to obovate, often with glandular margin. Small lvs often present at base of lateral shoots. Catkins erect or pendulous, appearing before, with, or after lvs. Fls entomophilous, each subtended by an entire bract. Perianth reduced to 1-2-(4) glands, more rarely these united to form a basal semi-annular lobed ring. ♂ fls with (1)-2-(12) stamens; anthers usually yellow, sometimes red. ♀ fls with 1 short or very short style and 2 stigmas. Capsule 2-valved, usually maturing well after lf maturity. Seeds nearly always numerous, very small or minute.
Catkins mostly ascending or spreading, seldom drooping, developing before, with, or less often after the lvs, their scales mostly entire, sometimes erose or shallowly toothed at the tip; fls with a single short and broad to slender and elongate ventral protuberance called a gland, or the staminate fls of some spp. also with a dorsal gland; stamens typically 2, seldom only 1 (by fusion of 2), or in some spp. 3–8; stigmas 2, entire or more often bifid; capsules 2-valved; shrubs or less often trees, sometimes depressed and mat-forming; winter-buds covered by a single nonresinous scale. 300+, mainly N. Temp. Taxonomy complicated by hybridization.
Trees or shrubs; twigs mostly under 2 mm diam.; winter buds with a single, non-sticky outer scale. Leaves rarely more than 5 cm wide, linear to elliptic, oblong or spathulate, rarely orbicular or cordate, sub-entire to serrulate or denticulate; petiole usually less than ¼ length of lamina. Flowers of both sexes subtended by an entire or serrulate floral bract and 1 or 2 small, tongue-like (1 rarely cup-shaped) nectaries. Stamens 1–15 (mostly 2, 3 or 5); filaments free or connate. Ovary 2-(rarely 3)-carpellate; stigma entire or 2-lobed, sessile or on a slender style; ovules 4 to many Capsule 2-valved. Seeds with silky hairs.
Trees or shrubs, rarely ± herbaceous. Buds with one outer scale. Leaves narrow. Flowers often appearing before leaves; disc of 1–2 fleshy glands (nectaries). Male flowers with 2–many stamens; anthers ovate or oblong. Female flowers with style divided into 2 entire or bifid stigmas. Capsule 2-valved.
Flowers often appearing before the leaves; disk of 1–2 fleshy glands (nectaries).
Female flowers with style divided into 2 entire or bifid stigmas.
Male flowers with 2-many stamens; anthers ovate or oblong.
Trees or shrubs, rarely somewhat herbaceous.
Ovary 2-merous seeds covered with hairs.
Buds with one outer scale.
Flowers often precocious
Shrubs or small trees
With narrow leaves
Leaves narrow.
