A monograph of the genus Colignonia (Nyctaginaceae)

Species of the neotropical genus Colignoniu are perennial herbs, subshrubs and lianas from 1 m to c. 15 m tall. The genus ranges from c. 5°N in Colombia to c. 28°S in Argentina and comprises six species. It occurs in the Andean montane rain forest and cloud forest, often in disturbed areas. The flowers are of two types and divide the genus into two sections, viz. Pterocarpae (3 spp) with a 3-lobed perianth, and Colignonia (3 spp) with a 5-lobed perianth. C. pentoptera is described as new. C. biumbellata is reduced to subspecific status under C. parviflora. C. acutifolia , originally described by Heimerl as a variety of C. glomerata , is referred to C. parviflora as a distinct variety of ssp. biumbellata . Several names are reduced to synonymy. The chromosome number 2 n = 34 is recorded for three species (Sect. Colignoniu ) and 2 n= 32 for three species (Sect. Pterocarpae ). The correlation between chromosome numbers and perianth type supports the subdivision of the genus. Considerable morphological variation, correlated with changes in temperature and altitude, was observed in the field and in plants under cultivation. Pollen morphology and relationships to other genera in the Nyctaginaceae are discussed. Colignonia seems most closely related to Mirabilis, Commicarpus, Boerhaaviu , and Pisoniella .