POLLEN MORPHOLOGICAL STUDIES ON TWO SOLANACEOUS GENERA: BRUGMANSIA PERS. AND DATURA L.

The exomorphological features of the pollen grains of five taxa of DaturaL. and six taxa of BrugmanisaPers. (Solanaceae) from Kerala and Tamil Nadu, India, have been studiedin detail. The two genera are closely related withBrugmansiabeing formerly included under Datura and later given a generic status. The pollen of both plant groups are also similar being 3-zonocolporate,large or medium andstriateor striato-reticulate, occasionally rugulate. The transverse or longitudinal alignment of the mural subunits in the exine has been considered to be the major distinguishing feature between pollen of the two genera. But in the present study, longitudinal and/or diagonal orientation of mural subunits has been observed in two varieties of B. sanguinea. Hence mural subunit alignment cannot be depended upon as a unique distinguishing character between pollen of the two genera. Although microscabrae were reported earlier from some members in both genera,adequate attention seems to be lacking with regard to these bodies. In the present study,microscabrae were observed in all the eleven members studied and showed distinction between the two genera, being large, nodular and dense in single or more rows in Brugmansia and small, granular, sparse and irregularly scattered in members of Datura. On the basis of the present observations, two pollen types are proposed here for the two genera studied viz. Brugmansia -type and Datura –type.