THE TAXONOMIC VALUE OF EPIDERMAL CHARACTERS IN THE LEAF OF HETEROMORPHA AND SOME RELATED GENERA (APIACEAE)

All 17 species of Heteromorpha Cham. & Schltdl. (sensu Humbert 1956), air three species of Polemannia Eckl. & Zeyh. and the monotypic Polema nniopsis B.L. Burb were investigated for leaf epidermal characters. St omatal type was anomocytic, with an exception in only one Madagascar s pecies, H. betsileensis. The distribution and density of stomata (on b oth leaf surfaces) are diagnostic for some species. The number, size a nd outline of normal epidermal cells are different in juvenile and adu lt leaves and these differences vary between species. Seven trichome t ypes are recognized which, when combined with dispersion pattern, also serve to characterise the various species and forms.