Coleus leaf trichomes SEM.jpg

''Coleus'' is a genus of annual or perennial herbs or shrubs, sometimes succulent, sometimes with a fleshy or tuberous rootstock, found in the Old World tropics and subtropics. The relationship among the genera ''Coleus'', '' Solenostemon'' and ''Plectranthus'' has been confused. ''Coleus'' and ''Solenostemon'' were sunk into ''Plectranthus'', but recent phylogenetic analysis found ''Plectranthus'' to be paraphyletic with respect to other related genera in the subtribe Plectranthinae. The most recent taxonomic treatment of the genus resurrected ''Coleus'', and 212 names were changed from combinations in ''Plectranthus'', ''Pycnostachys'' and ''Anisochilus''. ''Equilabium'' was segregated from ''Plectranthus'', after phylogenetic studies supported its recognition as a phylogenetically distinct genus.

''Coleus'' are cultivated as ornamental plants, particularly '' Coleus scutellarioides'' (syns. ''Coleus blumei'', ''Plectranthus scutellarioides''), which is popular as a garden plant for its brightly colored foliage.

Other species that produce root tubers are cultivated for food, including ''Coleus esculentus'', ''Coleus rotundifolius'' and ''Coleus maculosus'' subsp. ''edulis''.

Taxonomy

The genus ''Coleus'' was first described by João de Loureiro in 1790. Using morphological characters as a guide, it was distinguished from ''Plectranthus'' (first described by Charles L'Héritier in 1788) by having its four stamens fused together rather than free to the base. In 1962, J.K. Morton noted that fused stamens were more widespread than previously thought, and accordingly merged ''Coleus'' into ''Plectranthus'', while maintaining ''Solenostemon'' and some other genera as distinct., cited in Most sources followed Morton in submerging ''Coleus''; some kept ''Solenostemon'' distinct, although others submerged it into ''Plectranthus'' along with ''Coleus''.

A preliminary study of the tribe Ocimeae in 2004 showed that the subtribe Plectranthinae was monophyletic, with two main clades: one containing the type species of ''Coleus'' and including ''Solenostemon'', the other containing the type species of ''Plectranthus'' along with some other genera, so that ''Plectranthus'' when broadly defined was not monophyletic. A more detailed study in 2018 reached similar conclusions, and suggested that ''Coleus'' (including ''Solenostemon'') should be recognized again, ''Plectranthus'' more narrowly defined, and a new genus, '' Equilabium'' erected for a clade of former ''Plectranthus'' species mainly from tropical Africa. The many new binomial combinations needed to implement this approach were provided in 2019.

Phylogeny

Paton et al. in 2019 published a summary cladogram for the subtribe Plectranthinae, based on a study in 2018.
In the version below, the three genera accepted by Paton et al. that formed part of ''Plectranthus'' s.l. are highlighted.

Species

Paton et al. (2019) listed 294 species of ''Coleus'', many transferred from ''Plectranthus''. , ''Plants of the World Online'' listed 301. Species include:
*'' Coleus amboinicus'', syn. ''Plectranthus amboinicus''
*'' Coleus argentatus''
*''Coleus australis''
*'' Coleus barbatus'', syn. ''Plectranthus barbatus''
*'' Coleus caninus'', syn. ''Plectranthus caninus''
*''Coleus cataractarum''
*'' Coleus comosus'', syn. ''Plectranthus ornatus'' (sold as "''Coleus canina''" or "scaredy cat plant")
*''Coleus cremnus''
*''Coleus dissitiflorus''
*''Coleus esculentus'', syn. ''Plectranthus esculentus''
*''Coleus fredericii'', syn. ''Plectranthus welwitschii''
*''Coleus graveolens''
*''Coleus maculosus''
*''Coleus neochilus''
*''Coleus rotundifolius'', syn. ''Plectranthus rotundifolius''
*'' Coleus scutellarioides'', syns ''Coleus blumei'', ''Plectranthus scutellarioides''
*''Coleus socotranus'', syn. ''Plectranthus socotranus''
*''Coleus unguentarius'', syn. ''Plectranthus unguentarius''

Image gallery

Image:IndianBorage.jpeg, '' Coleus amboinicus''
Image:Starr_020114-0030_Plectranthus_parviflorus.jpg, ''Coleus australis''
File:Gardenology.org-IMG 3002 rbgs11jan.jpg, ''Coleus neochilus''
File:Leaves of Coleus in Monsoon in West Bengal, India.jpg, Cultivars in Monsoon, West Bengal, India

References

Sources

*

External links

EcoPort on ''P. rotundifolius''
(synonym of ''Coleus rotundifolius'')


(synonym of ''Coleus rotundifolius'')
* ttp://ecoport.org/perl/ecoport15.pl?searchType=entityDisplay&entityId=8753 EcoPort on ''P. esculentus'' (with tuber photo)(synonym of ''Coleus esculentus'')

Lamiales Newsletter on ''P. esculentus''
(synonym of ''Coleus esculentus'')

Little-known African Tubers
(discusses ''C. rotundifolius'' and ''C. esculentus'')

{{Taxonbar, from=Q17114803

Lamiaceae genera