Iochroma
An annotated list of the species and cultivars
IntroductionIochroma is a genus in the Solanaceae comprising some 24 species. They are shrubs or small trees with alternate, simple, and entire leaves. With the exception of one outlying species they occur at relatively high altitude in the forests of eastern South America. In the current taxonomic arrangement the Iochroma range from Colombia to Argentina but after a likely taxonomic revision (see below) the slightly smaller range is from Colombia to Peru. There is one outlying species in the Galapagos. The tubular to trumpet-shaped flowers may be blue, purple, red, yellow, or white and there is often a range of flower colours within a species. The fruits are berries usually containing sclerosomes as well as seeds, which are presumed to facilitate bird dispersal.
The genus is not completely known and is likely substantially to be revised in future. Several of the species listed here are known to have resulted from hybridisation in the wild. Recent research (Smith & Baum 2006) indicates that some of the species listed here are not Iochroma although changes in nomenclature have not formally been published pending further research. There are also known to be undescribed species.
The genus is currently divided into 3 sections, section Iochroma, section Lehmannia and section Spinosa. However, Smith and Baum (2006) have shown that in section Iochroma, the commonly cultivated Iochroma australe from Argentina and Bolivia is not an Iochroma but an Eriolarynx. Similarly in section Spinosa they have shown that neither species is an Iochroma; Iochroma cardenasianum belonging not in the tribe Iochrominae but in the tribe Datureae while Iochroma parviflorum is a Dunalia, not an Iochroma.
Only six species are known to be in cultivation, Iochroma australe, Iochroma calycinum, Iochroma cyaneum, Iochroma fuchsioides, Iochroma gesnerioides and Iochroma grandiflorum. The most variable species in cultivation is Iochroma cyaneum of which 11 forms have been given cultivar names. A number of other cultivars have not been identified to species; some are known to be hybrids of garden origin.
last updated 11/09/2008
last updated 11/09/2008