Pollen morphology of genus Rubus L., Part II. Introductory studies on the Malesian species of subgenus Micranthobatus

Abstract

The results of studies on pollen morphology of 6 Malesian Rubus species are presented (R. clementis, R. cordiformis, R. diclinis, R. megacarpus, R. novoguineensis and R. royenii var. ikilimbu). The examination has been made by SEM for the first time and also by LM. Detailed descriptions of the pollen grains are given. The pollen grains are small, isopolar and trizonocolporate. Ornamentation is generally classified as striate, although with some modifications. A striate-reticulate pattern has been observed in only one species (R. cordiformis). A rugulate-striate pattern represents R. novoguineensis. The typical striate patterns differed in form, width and orientation of the muri are observed in R. clementis, R. diclinis, R. megacarpus, R. royenii var. ikilimbu. The tectum perforations are clearly observed in R. clementis, R. diclinis, R. megacarpus, R. royenii var. ikilimbu. The relation between the species has also been disscused. Pollen morphological studies confirmed partly the systematic concept. Rubus megacarpus, R. cordiformis, R. novoguineensis show completely different patterns and can not be regarded as closely related species; Rubus clementis has its own striate pattern, which resembles the pollen morphological type of R. lucens (not included in this study). Rubus diclinis and R. royenii var. ikilimbu have almost the same type of pollen morphology.