Contributions to the Pollen morphology of the family Compositae

The pollen morphology of 24 species of Compositae belonging to 18 genera was examined by light and scanning microscopy. The present data confirms the eurypalynous nature of the family. Delimitation of the genera on the basis of pollen characters is less marked. Pollen grains usually radially symmetrical, isopolar rarely apolar; tricolporate, often porate. Shape commonly oblate-spheroidal to prolate-spheroidal, with some suboblate to subprolate types. Tectum echinate to echinolophate, often non-echinate. Tectum in-between the spines or spinules is sub-psilate, or perforated to striate. On the basis of the exine pattern, 4 distinct pollen types are recognized viz., Pollen type-I: Dicoma tomentosa, Pollen type-II: Eclipta prostrata, Pollen type-III: Echinops echinatus and Pollen type-IV: Launaea nudicaulis. Within the pollen types, pollen characters are significantly sufficient for characterization of the species. An interesting correlation observed is that the taxa having spiny capitula have a mostly non-echinate or spinulose tectum with very thick exine (7-25 ?m).