Genus of about 150 species of mainly evergreen, epiphytic orchids from the US, Mexico, and the West Indies. They have fleshy pseudobulbs, which are rounded or elongated, and usually 2 narrowly oblong to strap-shaped or linear to elliptic, fleshy or leathery leaves. Attractive, variable, often fragrant flowers are produced from the apexes of the pseudobulbs, in late spring and summer, but often intermittenly throughout the year.