Dichromanthus is a small genus of terrestrial orchids in the family Orchidaceae, order Asparagales. As currently delimited the genus is monophyletic and comprises four species. It belongs to the subtribe Spiranthinae, a group of ground-dwelling orchids widespread in the Americas.
The genus ranges from the southwestern United States — principally Texas and Arizona — southward through most of the major Mexican mountain ranges and continuing into Central America as far as Guatemala, El Salvador, and Honduras. Most species are widespread and locally common across this arc; the exception is Dichromanthus yucundaa, a narrow endemic confined to the Mexican state of Oaxaca.
Dichromanthus cinnabarinus (cinnamon-red spiral orchid) is perhaps the best-known member, its brilliantly coloured flowers in orange-red to cinnabar tones making it conspicuous in seasonally dry grasslands and open pine-oak forests. Dichromanthus aurantiacus is similarly showy, with orange flowers, and occupies a broadly overlapping range through much of Mexico into Honduras.
Distribution
Dichromanthus is native to the southwestern United States (Texas and Arizona), most Mexican mountain ranges, and extends into Central America through Guatemala, El Salvador, and Honduras. The narrow endemic D. yucundaa is restricted to the Mexican state of Oaxaca, while the remaining three species are widespread and locally common across this range.
Taxonomy Notes
The genus Dichromanthus belongs to the family Orchidaceae (order Asparagales) and is placed in the subtribe Spiranthinae. Several of its species were formerly placed in other genera (notably Spiranthes and Stenorrhynchos) before being transferred to Dichromanthus by Salazar, Soto Arenas, and Garay based on molecular and morphological evidence. The genus is currently considered monophyletic.
