Original Research

The genus Echium (Boraginaceae) in southern Africa

E. Retief, A. E. van Wyk
Bothalia | Vol 28, No 2 | a634 | DOI: https://doi.org/10.4102/abc.v28i2.634 | © 1998 E. Retief, A. E. van Wyk | This work is licensed under CC Attribution 4.0
Submitted: 03 October 1998 | Published: 06 October 1998

About the author(s)

E. Retief, National Botanical Institute, South Africa
A. E. van Wyk, National Botanical Institute, South Africa

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Abstract

The genus Echium L. (Boraginaceae) comprises about 60 species, mainly from Macaronesia. Europe, western Asia and North Africa. Two species E plantagineum L. and E. vulgare L. were introduced into southern Africa and have become naturalised. The species occur mainly as roadside weeds in the region. Echium is closely related to Lobostemon Lehm. (incl. Echiostachys Levyns), endemic in the southwestern Cape region. Pollen morphology shows a remarkable similarity between these genera, even suggesting that they could be merged. However, other characters, such as bilobed styles (Echium) versus undivided ones (Lobostemon) and the presence of an annulus, composed of a minute collar or 5-10 minute hairy lobules, at the bottom of the corolla tube inside (Echium), in contrast to hairs and/or scales at the base of the filaments (Lobostemon) contradict the pollen structure, and Echium and Lobostemon are therefore regarded as two separate genera. Significant taxonomic characters, an identification key, full descriptions, illustrations and distribution maps of E. plantagineum and E. vulgare are given.


Keywords

Boraginaceae; <i>Echium</i> L.; indumentum; <i>Lobostemon</i> Lehm.; phytogeography; pollen; relationships; southern Africa; taxonomy; weed

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Crossref Citations

1. Taxonomy of Echium (Boraginaceae) species from Cape Verde Islands
Maria M. Romeiras, Lia Ascensão, Maria C. Duarte, Maria A. Diniz, Maria S. Pais
Australian Systematic Botany  vol: 21  issue: 1  first page: 26  year: 2008  
doi: 10.1071/SB07016