Iochroma is a genus of about 34 species of shrubs and small trees found in the forests of South America. They range from Colombia to Argentina or when certain species are excluded (see below) from Colombia to Peru. Their hummingbird pollinated flowers are tubular or trumpet-shaped, and may be blue, purple, red, yellow, or white, becoming pulpy berries. The cupular calyx is inflated in some species. The leaves are alternate, simple, and entire.
Iochromas are cultivated as flowering ornamentals and in cooler zones (zones 7-8/9) make useful patio shrubs for summer display or conservatory plants. The majority are not frost hardy and must be overwintered under protection. In warmer zones (zones 9-10) they can be used as landscape plants. They are commonly trained as standards (topiary) to control their size and shape. Iochroma flowers attract hummingbirds (Americas only) and bees to gardens.
Like many plants in the Solanaceae, Iochroma species contain phytochemicals with potential pharmaceutical value but the genus has not been exhaustively studied in this respect. Iochroma fuchsioides is taken by the medicine men of the Kamsa Indians in the Colombian Andes for difficult diagnoses the unpleasant side effects lasting several days (Schultes & Hoffman 1992). A variety of withanolides (Alfonso et al. 1993) and hydroxycinnamic acid amides (Sattar et al. 1990) have been isolated from Iochroma species.
The family Solanaceae is further divided into subfamilies, tribes and subtribes. Iochroma is in the subtribe Iochrominae along with the genera Acnistus, Dunalia, Eriolarynx, Saracha, and Vassobia.
The genus Iochroma is not completely known. Several of the species listed here are known to have resulted from hybridisation in the wild and there is extensive synonymy which is not recorded here. Recent research indicates that some of the species listed here are not Iochroma (see notes) although changes in nomenclature have not formally been published. There are also known to be undescribed species.
The genus is currently divided into 3 sections.
- Iochroma albianthum S. Leiva
- Iochroma australe Grisebach (see notes)
- Iochroma ayabacense S. Leiva
- Iochroma calycinum Bentham
- Iochroma confertiflorum (Miers) Hunziker
- Iochroma cornifolium Miers
- Iochroma cyaneum (Lindley) M. L. Green
- Iochroma edule S. Leiva
- Iochroma fuchsioides Miers
- Iochroma gesnerioides (Humboldt, Bonpland & Kunth) Miers
- Iochroma grandiflorum Bentham
- Iochroma loxense Miers
- Iochroma nitidum S. Leiva & V. Quipuscoa
- Iochroma peruvianum (Dunal) J. F. Macbride
- Iochroma piuram S. Leiva
- Iochroma sagasteguii sp. nov ined.
- Iochroma salpoanum S. Leiva & P. Lezama
- Iochroma schjellerupii S. Leiva & Quipuscoa
- Iochroma squamosum S. Leiva & V. Quipuscoa
- Iochroma stenanthum S. Leiva, V. Quipuscoa & N. W. Sawyer
- Iochroma tingoense sp. nov ined.
- Iochroma tupayachianum S. Leiva
- Iochroma umbellatum (Ruiz & Pavon) D'Arcy
- Iochroma cardenasianum Hunziker (see notes)
- Iochroma parvifolium (Roemer & Schultes) D’Arcy (see notes)
- Iochroma warscewiczii Regel
Iochroma australe is not an Iochroma but an Eriolarynx. Occurring in Bolivia and Argentina this is the southernmost species of Iochroma and its removal from the genus affects the geographic range as indicated above.
Iochroma cardenasianum is not an Iochroma and not a member of the tribe Physaleae (incl. subtribe Iochrominae) but the tribe Datureae.
Iochroma parviflorum is not an Iochroma but a Dunalia.
Iochromas as ornamentals
Several forms of Iochroma (some wild collected, some garden hybrids) have been given cultivar names. Some of the cultivars have been assigned to species but others, mainly hybrids, have not. There may be some synonymy in this list.
- Iochroma australe ‘Andean Snow’
- Iochroma australe ‘Bill Evans’
- Iochroma australe ‘Sunrise’
- Iochroma calycinum ‘Vlasta’s Surprise’
- Iochroma cyaneum ‘Album’
- Iochroma cyaneum ‘Apricot Belle’
- Iochroma cyaneum ‘Indigo’
- Iochroma cyaneum ‘Karl Hartweg’
- Iochroma cyaneum ‘John Miers’
- Iochroma cyaneum ‘Royal Blue’,
- Iochroma cyaneum 'Royal Queen' = I. cyaneum 'Indigo'
- Iochroma cyaneum ‘Sky King’,
- Iochroma cyaneum ‘Trebah’
- Iochroma cyaneum ‘Woodcote White’
- Iochroma gesnerioides ‘Coccineum’
- Iochroma gesnerioides var. flavum
- Iochroma ‘Ashcott Red’
- Iochroma ‘Burgundy Bells’
- Iochroma ‘Frosty Plum’
- Iochroma ‘Ilie’s Plum’
- Iochroma ‘Plum Beauty’
- Iochroma ‘Plum Delight’
- Iochroma ‘Purple Haze’
- Iochroma 'Ruby Red' (I. cyaneum 'Royal Blue' x I. 'Sunset')
- Iochroma ‘Sunset’
- Iochroma ‘Wine Red’
- Shaw, J. M. H. (1998) A Review of Iochroma in Cultivation. New Plantsman 5(3): 154-192.
- Smith, S. D. and Baum D. A. (2006) Phylogenetics Of The Florally Diverse Andean Clade Iochrominae (Solanaceae). American Journal Of Botany 93(8): 1140–1153.
- Sattar, E. A., Glasl, H., Nahrstedt, A., Hilal, S. H., Zaki, A. Y. and El Zalabani, S. M. H. (1990). Hydroxycinnamic acid amides from Iochroma cyaneum. Phytochemistry 29 (12) : 3931 - 3933.
- Alfonso, D., Bernardinelli, G. and Kapetanidis, I. (1993). Withanolides from Iochroma coccineum. Phytochemistry 34 (2) : 517 - 521.
- Schultes, R. E. and Hoffman, A. (1992). Plants of the Gods. Their sacred, healing and hallucinogenic powers. Healing Arts Press, Rochester, Vermont. p. 46.
Constantine, D. R. (2008): Iochroma - an annotated list of the species and cultivars