Fls unisexual or seldom perfect; cal minute, 4-lobed or irregularly erose, or none; cor in our spp. none; stamens mostly 2; ovary bilocular, with 2 ovules per locule; fr a 1-seeded samara, the wing chiefly or wholly distal; trees with deciduous, pinnately compound lvs, the fls in dense fascicles, short racemes, or panicles, from the axils of the previous season. 65, N. Hemisphere.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.