Columnea is a large genus of flowering plants in the family Gesneriaceae, the same family that includes African violets and gloxinias. Estimates of its size vary by source — Wikipedia reports about 200 species, Plants of the World Online accepts 228, and the specialist Gesneriad Reference Web puts the total "somewhere around 300" — but all sources agree that it is among the largest genera of neotropical Gesneriaceae. The genus was published by Carl Linnaeus in Species Plantarum (1753), crediting the earlier work of the French botanist Charles Plumier, and was named for the 16th-century Italian botanist Fabio Colonna (Latinized as "Fabius Columnus").
Most Columnea are epiphytic herbs or small shrubs that grow on the bark and branches of trees in humid, tropical forest. Their stems are often pendent or trailing, suiting the lifestyle of a plant rooted in a layer of moss or detritus on a horizontal limb. The leaves are typically arranged in opposite pairs, often unequal in size, and in many species the underside or the bracts are flushed with red — a colour cue tied to pollination.
The genus is best known for its showy flowers, which are tubular or oddly shaped, usually large, and brightly coloured in shades of red, orange, and yellow. The corolla is two-lipped and frequently hooded; in some species the gibbous swelling at the base of the tube and the protruding lip have inspired common names such as "flying goldfish plant" and "goldfish vine." These flowers are pollinated chiefly by hummingbirds — the Gesneriaceae account on Wikipedia specifically names Columnea alongside Asteranthera and Sinningia as classic examples of bird-pollinated, red-flowered Gesneriaceae.
Columnea is native to the American tropics and the Caribbean, ranging from Mexico south through Central America and the Greater and Lesser Antilles to much of tropical South America, including Colombia, Ecuador, Peru, Bolivia, the Guianas, Venezuela, and northern, north-eastern and south-eastern Brazil. Several species — including C. crassifolia, C. hirta, C. microphylla, C. glabra, and the popular C. × banksii hybrid — are widely cultivated as houseplants and hanging-basket subjects, with C. × banksii holding the Royal Horticultural Society's Award of Garden Merit. The genus is bordered by several segregate genera that have at times been split off; POWO currently treats 18 of these — among them Dalbergaria, Collandra, and Bucinellina — as heterotypic synonyms of Columnea.
Etymology
The genus was established by Carl Linnaeus in Species Plantarum (1753), drawing on the earlier work of the French botanist Charles Plumier — reflected in the standard authority citation "Plum. ex L." The name commemorates the Italian botanist Fabio Colonna (1567–1640), whose surname was Latinized as "Fabius Columnus." Colonna is regarded as one of the earliest authors to apply systematic illustration to plant taxonomy, and Linnaeus's choice tied the new genus to that early-modern botanical tradition.
Distribution
Columnea is restricted to the Neotropics. Plants of the World Online records the genus as native from Mexico through tropical America and the Caribbean, covering Belize, Bolivia, northern, north-eastern and south-eastern Brazil, Colombia, Costa Rica, Cuba, the Dominican Republic, Ecuador, El Salvador, French Guiana, Guatemala, Guyana, Haiti, Honduras, Jamaica, the Leeward Islands, central, Gulf, north-eastern and south-eastern Mexico, Nicaragua, Panama, Peru, Puerto Rico, Suriname, Trinidad and Tobago, Venezuela, and the Windward Islands. Diversity is concentrated in the wet montane forests of the northern Andes (Colombia, Ecuador, Peru) and in the Central American mountains.
Ecology
The great majority of Columnea species are epiphytes, growing on tree trunks and branches in humid tropical and montane forest. Their pendent, often slender stems and unequal opposite leaves are characteristic of this lifestyle. Flowers are predominantly pollinated by hummingbirds: the Wikipedia treatment of Gesneriaceae lists Columnea (together with Asteranthera and Sinningia) as a textbook example of bird pollination in the family, with two-lipped red flowers matched to the visual and morphological preferences of hummingbird visitors.
Cultivation
Columnea species and hybrids are popular ornamentals, particularly in hanging baskets where their trailing stems and brightly coloured flowers are shown to advantage. They are described as easy to grow under indoor or greenhouse conditions, requiring bright light, good air circulation and a free-draining growing medium that reflects their epiphytic habit. Specialist sources note that many species do well in ordinary home conditions. The hybrid Columnea × banksii has been recognised with the Royal Horticultural Society's Award of Garden Merit.
Taxonomy notes
Columnea Plum. ex L. was first published in Species Plantarum: 938 (1753) and belongs to the family Gesneriaceae (order Lamiales), within subfamily Gesnerioideae and tribe Gesnerieae. Estimates of the species total vary by source: Plants of the World Online accepts 228 species, the Gesneriad Reference Web cites "somewhere around 300," and the Wikipedia summary gives "approximately 200." POWO also treats 18 heterotypic genus-level names — among them Aponoa Raf., Collandra Lem., Dalbergaria Tussac and Bucinellina — as synonyms of Columnea, reflecting a long history of splits and lumps in the group. Both GBIF and POWO recognise the genus as accepted.
History
Linnaeus published Columnea in Species Plantarum (1753), explicitly building on the pre-Linnaean treatment of Charles Plumier — hence the authority "Plum. ex L." The genus has been treated since by numerous specialists, with several segregate genera (Dalbergaria, Collandra, Bucinellina, Trichantha and others) successively split off and later folded back in; POWO's current circumscription lists 18 such names as heterotypic synonyms.
