Structure and functioning of anthers have been studied in Ficus carica L., F. sycomorus L. and F. religiosa L. Polleniferous figs of F. carica produce numerous male flowers with plenty of pollen (multistaminate type). Mature anthers contain a normal fibrous layer and open spontaneously. On the other hand, figs of F. sycomorus produce a comparatively small number of male flowers, their anthers have a degenerated endothecium and do not dehisce normally. In pollination (pollen loading and unloading) the great differences occurring in the organization of the androecium of F. carica and F. sycomorus may be seen to be associated with different behaviour patterns of their specific pollen vectors, the agaonid wasps Blastophaga psenes and Ceratosolen arabicus, respectively. While the pollinators of F. carica become passively coated with pollen on their exit from the native fig (topocentric pollination), the pollen vectors of F. sycomorus help in opening of the anthers and load the pollen purposively, by direct lifting of the pollen from the anthers on to special pockets on the body of the insect (ethodynamic pollination). Thus, in the context of pollination, the complementary nature of the characteristics of the two participants of fig symbiosis is evident.

SUMMARYThe anther collar, i.e. the distal part of the stamen filament, was studied in .S6 species belonging to 11 tribes of Asteraceae. In all the species, the structure of the collar differed considerably from that of the remaining part of the filament. Cells of the abaxial collar epidermis are large and have lignified walls. The cells of the adaxial epidermis are smaller and their walls, similar to epidermal cell walls in the remaining part of the filament, are devoid of lignin. Variation was noted in the shape and size of the collar and in the thickenings of the epidermal walls. Presence of lignin in the collar indicates that this part does not participate in contraction of the filaments in species with sensitive stamens. It is suggested that the differences in structure and shape hetween the abaxial and adaxial sides of the collar determine an outward orientation of the curvature in the more elastic lower portion of the filament. This curvature leads to the formation of openings through which an insect may insert its proboscis to probe for nectar.

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