Remarks.—The description has been drawn from ample material from this single tree.
CARYA BUCKLEYI var. ARKANSANA Sargent. (× 1/2.)
Trees or shrubs with simple, petioled, alternate (in pairs on the older branches of Betula) leaves; staminate flowers in long drooping catkins, 1-3 in the axil of each bract, the pistillate in short lateral or terminal aments; fruit a nut or samara.
| Staminate flowers solitary in the axil of each bract, without a calyx, pistillate flowers with a calyx; nut wingless. | |
| Bark of tree smooth; staminate aments in winter enclosed in bud scales; nut exposed, its subtending bract more or less irregularly 3-cleft | [1 Carpinus.] |
| Bark of older trees shreddy; staminate aments in winter naked; nut enclosed in a bladder-like bract | [2 Ostrya.] |
| Staminate flowers 3-6 in the axil of each bract, with a calyx, pistillate flowers without a calyx; nut winged. | |
| Winter buds sessile; stamens 2; fruit membranous and hop-like; fruiting bract deciduous at the end of the season when the nut escapes | [3 Betula.] |
| Winter buds stalked; stamens 4; fruit woody and cone-like; fruiting bracts woody and persisting after the nuts escape | [4 Alnus.] |