The present paper, devoted to the genus Nerium L. covers taxonomic and other aspects of the wild oleander and of the oleander cultivars.
The ﬁrst section deals with the wild oleander and includes a revision of the genus. A precursor of the revision of Nerium L. was published by Leeuwenberg in 1984 and has been completed by the present author under Leeuwenberg’s supervision. The study is based on several hundreds of herbarium specimens, most of them well prepared and richly provided with flowers and/or fruits. The genus Nerium L. is considered to be monotypic, its single species being Nerium oleander L.
A distribution map of the naturally occurring Nerium oleander L. is included. The ﬂower of Nerium oleander L. features a pistil with a highly differentiated pistil head. An experiment executed to pinpoint the location of the stigmatic area is described and the pollination mechanism is discussed. Oleanders are known as poisonous and medicinal plants. Bisset discusses the phytochemistry of Nerium L.in the second section.
The third section deals with the cultivated oleander. An inventory of the oleander cultivars has been compiled by the present author, resulting in a tentative checklist of oleander cultivars. Oleander cultivars vary in form, colour and scent of the ﬂowers, and in habit. Several cultivars have variegated leaves. Oleanders are very popular ornamental plants and commonly cultivated in tropical and subtropical countries as a garden shrub and elsewhere as a pot plant. The history of the oleander in cultivation is discussed. The phytochemistry chapter was written by N. G. Bisset; F. J. J. Pagen authored the other chapters.