Plants 0.5-7 cm. Stems 0 or 1-10, erect to prostrate; branches usually 0, sometimes proximal and/or distal. Leaves basal or cauline, sessile or petiolate, distal congested, larger than proximal (if present), largest 4-22(-32) × 0.5-4(-5) mm; petioles: lengths 0-1.5 times blade lengths, bases scarcely thickened, pliant to somewhat cartilaginous; capitular leaves 6-12 (rarely more) per glomerule or head, whorled, ± erect or distally spreading, unlike pistillate paleae. Heads terminal, borne singly or, rarely, in dense glomerules (3-7 mm diam.) of 2-8 mixed with leaves and, rarely, some borne singly in axils (then smaller), campanulate, 2-4 × 1.5-3.5 mm, heights 1-1.5 times diams. Receptacles distinct, 0.9-1.9 × 0.8-1.7 mm. Pistillate paleae in 2-5 series, spirally ranked, broadly spatulate, 1-3 mm. Staminate paleae surpassing pistillate, 1.6-3.2 mm, lengths 0.6-0.8 times head heights; apices spreading. Functionally staminate florets 2-5(-12); corollas 0.6-1 mm. Cypselae 0.6-1.6 mm.

The varieties of Hesperevax acaulis show enough geographic and ecologic segregation correlated with morphologic differences to warrant taxonomic recognition. Across west-central California, where all three are broadly sympatric, the varieties tend to occur in different habitats and/or elevation zones. Intermediate specimens are difficult to assign with confidence.