Noel H. Holmgren in Flora of North America (vol. 4)
monoecious or dioecious, herbage densely tomentose, hairs stellate.
erect, not jointed or armed; basal branches woody, flowering branches herbaceous.
alternate, petiolate; blade linear to narrowly lanceolate, not fleshy, base truncate, margins entire, revolute, apex blunt.
axillary clusters or small spikes.
unisexual; staminate flowers with bractlets absent, perianth 4-parted, stamens 4; pistillate flowers enclosed in 2 partially connate, slightly keeled, densely hirsute bractlets with free tips hornlike, perianth absent, stigmas 2, elongate.
ovate, flat utricles; pericarp free, thin
vertical, ovate; seed coat brown, covered with white hairs; embryo annular, perisperm copious.
Species within checklist: