Small gnarly shrubs or half-shrubs or herbs, rarely trees up to 8 m, in a few species the twigs thorny and microphyllous. Leaves in a spiral or rarely (sub)opposite, often herbaceous, sometimes leathery, more or less sessile with a tapering base, to c. 15 by 4 cm, but mostly smaller to sometimes almost needle-shaped, margin entire to incised, rarely thickened underneath, the teeth sometimes glandular. Stipules generally small and mostly caducous. Flowers generally solitary in the leaf axils, rarely in more or less reduced axillary cymes or dichasia up to several cm long or in raceme-like elongated monochasia, rarely in a terminal leafy panicle; Flower 0.3-2 cm, bisexual, but rarely cleistogamous, zygomorphic. Sepals subequal, small, more or less triangular, persistent, rarely the margin with deep incisions. Petals unequal, persistent, posterior ones small and straight, middle ones longer and falcate, anterior one extended to a lip, with a claw more or less deeply saccate to shortly spurred and distinct blade often hairy above. Ovary with 3 placentas bearing 3-24 ovules; Fruit subtended by the dried up flower, c. 1 cm in size, subglobose before maturity, capsular with 3 leathery valves. Seeds a few mm, ellipsoid, mostly with a small caruncula.
Africa: present Australasia: Madagascar: present New Caledonia: absent present New World: present Pantropical: tropical and subtropical regions of the world: present
Tropical and subtropical regions of the world, preferring a dry period. The number of species that will stand in a critical monograph is hard to estimate; there may be about 50 in the New World, some in Africa and Madagascar, some in Australia, a few woody ones in New Caledonia. The one Malesian species is palaeotropical (seems not to occur in New Caledonia) and possibly pantropical.
The literature cited under the genus refers chiefly to the most recent revisions in all parts of the world. The name was in 1905 conserved over Calceolaria LOEFL. 1758. The above description applies to the entire genus; it was largely based on SCHULZE. The specific description below was made on material from Malesia, where only part of the diversity of the species is represented.
MORTON - in Contr. U.S. Nat. Herb. 1944
SCHULZE - in Bot. Jahrb. 1936
B. & H. - in Gen. Pl. 1862: 117
DOMIN - in Bibl. Bot. 1928
H. PERR. - in Humb. Fl. Madag. 1959: f. 1: 2-11
BOERL. - in Handl. 1890: 65
SPARRE - in Lilloa. 1950: 4 pi.
BAILL. - in Bot. Médic. 1884: 841
MELCH. - in E. & P., Nat. Pfl. Fam., ed. 2, 21. 1925: 357
ROBSON - in Bol. Soc. Brot. 1958