Pollen grains in Palmae

The paper gives an account of Palmae pollen grains, which usually have a smooth sporoderm but rarely are spiny or warty. The sporoderm is spiny in the Pandanaceae and smooth in the Sparganiceae, families closely related to the Palmae. The classification of the Palmae into subfamilies as given by Drude (1889) and Moore (1960) has been taken as standard, and the characteristics of pollen grains in various genera belonging to these have been compared. Apart from shape, size, polysporic or unisporic nature of the pollen grains, single double nuclei at the time of shedding, it is thought that more reliable characteristics for classification and phylogeny are the number and nature of the colpi. There is a strong correlation in the primitive nature of monocolpate pollen grains among many species of Cocos, but not in all species believed to belong to that genus. For example, C. schizophylla has a triradiating colpus, considered to be primitive. This agrees with the view expressed by Beccari (1917) and Beccari and Pichi-Sermolli (1956) regarding the redistribution of species of this genus. That Nipa is a distinct, isolated member of the Palmae is supported by its non-colpate pollen grains. In the closely related tropical palm, Phytelephas macrocarpa, pollen grains are monocolpate. These two members thus seem to be unrelated, a conclusion further supported by morphology, anatomy, and embryology. Palynologically and anatomically, Nipa shows affinities with the related families Pandanaceae, Aroideae, and Cyclanthaceae