Chu Gelin in Flora of North America (vol. 4)
prostrate or ascending, diffusely branched, terete, not jointed or armed, not fleshy.
alternate, petiolate; blade rhombic-ovate to suborbicular, base abruptly short-cuneate, margins repand-dentate, apex rounded or acute, sparsely covered with inflated unicellular trichomes (scurfy when dry).
staminate and pistillate flowers in mixed clusters in axils of nearly all leaves.
perianth segments usually 4; stamens usually 4; rudimentary ovary present.
perianth segments becoming marginally connate, 4-lobed; stigmas 2, filiform.
utricles, enclosed by enlarged, compressed perianth; pericarp appressed to seed, thinly membranous.
vertical, ovate to triangular-ovate; seed coat reddish brown, thick, membranous; embryo subannular, surrounding perisperm.
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Species within checklist: