Anatomical contributions to plant taxonomy I. Floral and vegetative anatomy of Eliaea from Madagascar and Cratoxylum from Indo-Malesia (Guttiferae)

The floral and vegetative anatomy of the closely allied guttiferous genera Cratoxylum (Indo-Malesia) and Eliaea (Madagascar) is described. Although the two taxa have many features in common, differences are substantial enough to recognize them as distinct genera, as appears from the following survey: Cratoxylum Ovary with 12 or more ovules Ovary with 3(or 4) incomplete true septa Styles and filaments glabrous Secondary xylem with scarcely pitted fibres Vessels solitary and in radial multiples Silica bodies present in ray cells of wood Eliaea Ovary with 6(—8) ovules Ovary with 6(or 8) incomplete septa, three being true, three false Styles and filaments mostly villous Secondary xylem with densely pitted fibretracheids Vessels almost exclusively solitary Silica bodies absent The vascularization and insertion of the hypogynous scales in both genera favours the view that these structures may be interpreted as staminodial derivatives. In some species of Cratoxylum a further differentiation into taxa of lower rank is suggested by the presence or absence of abaxial epidermal papillae on the leaves; this is related to geographical distribution. Floral and xylem specialization of Cratoxylum and Eliaea are discussed. The xylem structure of Eliaea shows more primitive features than that of Cratoxylum, but the flowers seem to be more specialized. The possible implications of these findings for plant geography are discussed. In Cratoxylum the section Isopterygium (C. arborescens and C. glaucum) is very different in its wood anatomy from the other representatives of Cratoxylum. This difference (concerning parenchyma distribution) is correlated with the evergreen habit in the section Isopterygium. The other sections of Cratoxylum are deciduous. A comparison with some data from literature about other groups with deciduous and evergreen members is made.