Species of the neotropical genusColignoniuare 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, andColignonia(3 spp) with a 5‐lobed perianth.C. pentopterais described as new.C. biumbellatais reduced to subspecific status underC. parviflora. C. acutifolia, originally described by Heimerl as a variety ofC. glomerata, is referred toC. parvifloraas 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.Colignoniaseems most closely related toMirabilis, Commicarpus, Boerhaaviu, andPison
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