WETZEL, SABINE B., ALAN PATON, KONRAD BACHMANN, AND FRANK R. BLATTNER.* Institute of Plant Genetics and Crop Plant Research (IPK), D-06466 Gatersleben, Germany, Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK. - Phylogenetic studies within the genus Ocimum L. (Labiatae) based on ITS sequences of the nrDNA.
Ocimum L. is a genus within the Labiatae, which contains
several spices and medicinal herbs. The economically most important
species are O.basilicum, O.minimum,
O.americanum and the hybrid O. x
citriodorum, which are used for essential oil production and as
pot herbs. Species number is estimated between 30 and 160. A recent
revision of the genus based on morphology and cytology described 65
species native in the tropical areas of America, Africa and Asia
(Paton et al. 1999, in: Hiltunen and Holm Basil: the genus
Ocimum.) Some species were placed into synonymy, and the genera
Erythroclamys, Becium and Orthosiphon subgen.
Nautochilus were incorporated into the genus Ocimum.
Recently also the genus Plectranthus is suggested to be part of
To assess phylogenetic relationships of Ocimum
and related genera, the morphological hypothesis was tested with an
analysis of nrDNA internal transcribed spacer sequences (ITS).
Cladistic and phenetic analyses resulted in a paraphyletic genus
Ocimum with Plectranthus, Aeollanthus, Catoferia, and
Pycnostachys grouping within Ocimum. Plectranthus
is a monophyletic sistergroup of subg. Nautochilus,
Aeollanthus, which morphologically resembles
Plectranthus,is part of section Gratissima. Most
morphologically defined sections of Ocimum could be confirmed
by the molecular analysis. However, O.minimum, often
considered as a subspecies of Ocimum basilicum, is not
conspecific with O.basilicum and even groups outside of
Key words: ITS, Lamiaceae, Ocimum, phylogeny