Linnaeus, Sp. Pl. 1: 204. 1753, name conserved.
perennial or annual.
0.4-2 m, pilose or puberulent.
elliptic, ovate, or broadly ovate to orbiculate, obovate-orbiculate, or broadly rhombate, 1-20 × 2-6 cm, adpressed-pubescent abaxially and adaxially.
to 30 cm; bracts mem-branous; bracteoles long-aristate, spinose; wings attached at sides and base.
tepals 4 or 5, length 3-7 mm; pseudostaminodes with margins fimbriate at apex, often with dorsal scale.
± cylindric, 2-4 mm, apex truncate or depressed.
Varieties 6 (2 in the flora): se United States, Mexico, West Indies, Central America, South America, Eurasia, Africa.
is a variable, pantropical species divided into six varieties (C. C. Townsend 1974), two of which occur in the flora. The variety with a long perianth and acuminate leaves has long been called var.
; the variety with a short perianth and blunt leaves, var.
. However, A. Cavaco (1962) showed that the type of var.
must be the type of the species
, thus var.
is a homotypic synonym of var.
. Townsend made the combination
for plants previously called var.