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Further disintegration and redefinition of Clerodendrum (Lamiaceae): Implications for the understanding of the evolution of an intriguing breeding strategy

Citation

Yuan, YW and Mabberley, DJ and Steane, DA and Olmstead, RG, Further disintegration and redefinition of Clerodendrum (Lamiaceae): Implications for the understanding of the evolution of an intriguing breeding strategy, Taxon, 59, (1) pp. 125-133. ISSN 0040-0262 (2010) [Refereed Article]

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Copyright © 2010 by International Association for Plant Taxonomy

Official URL: http://www.botanik.univie.ac.at/iapt/s_taxon.php

Abstract

The genus Clerodendrum s.l. is polyphyletic. Although recent studies have resulted in C. subg. Cyclonema and C. sect. Konocalyx being removed to the resurrected genus Rotheca, and the unispecific genus Huxleya being sunk into Clerodendrum, it has been unclear whether Clerodendrum as currently circumscribed is monophyletic, particularly in relation to the American genera Aegiphila, Amasonia, and Tetraclea. This phylogenetic study employs four relatively fast-evolving chloroplast DNA regions, trnT-L, trnL-F, trnD-T, and trnS-fM, to clarify the generic boundaries of Clerodendrum and its relationship to allied genera. The results corroborate previous studies that there are three well-supported clades in the currently recognized Clerodendrum: an Asian clade, an African clade, and a Pantropical Coastal clade. The Asian clade and African clade are sister groups and together form a monophyletic group. However, the Pantropical Coastal clade is more closely related to the three American genera than it is to the other two Clerodendrum clades. In addition, a Caribbean species, C. spinosum, is found to be more closely related to the American genera than it is to any of the three major Clerodendrum groups. These results indicate that Clerodendrum as currently circumscribed is not monophyletic. We propose to separate the Pantropical Coastal clade and C. spinosum by reviving the genera Volkameria (including Huxleya) and Ovieda, respectively for these, and to restrict Clerodendrum to the Asian and African clades. Brief descriptions of the genera to be recognized are provided. All Neotropical ‘Clerodendrum’ taxa are referred to other genera, necessitating six new combinations, which are also provided, where required, for two other well-studied Old World Volkameria species; all names ever used in Ovieda are given their modern placings (two placed newly in synonymy). The study also sheds light on the evolution of an intriguing breeding strategy that avoids self-pollination or/and sexual interference. This strategy involves presentation of pollen and stigma in the centre of the flower in a sequential fashion by moving the filaments and style. It appears to have evolved in the common ancestor of Clerodendrum, Volkameria, Ovieda, Amasonia, Tetraclea, Aegiphila and Kalaharia, and still occurs in all of these taxa except Aegiphila, where it has been succeeded by a heterostylous system.

Item Details

Item Type:Refereed Article
Keywords:Aegiphila; breeding strategy; chloroplast DNA; Clerodendrum; Huxleya; Ovieda; phylogeny; Volkameria
Research Division:Biological Sciences
Research Group:Evolutionary Biology
Research Field:Plant Systematics and Taxonomy
Objective Division:Environment
Objective Group:Flora, Fauna and Biodiversity
Objective Field:Flora, Fauna and Biodiversity of environments not elsewhere classified
Author:Steane, DA (Dr Dorothy Steane)
ID Code:67512
Year Published:2010
Web of Science® Times Cited:18
Deposited By:Plant Science
Deposited On:2011-03-04
Last Modified:2011-05-13
Downloads:0

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