| Abstract: | Pollen grains of 30 species and 2 varieties from China, belonging to 5 genera (out
of 36 species in 5 genera) of Hydrocotyloideae and Saniculoideae, were examined with light
microscope and scanning electron microscope. 1.Six types of the pollen shape are recognized
in Hydrocotyloideae and Saniculoideae from China, and their evolutionary trend is from
rhomboidal→subspheroidal→ellipsoidal→subrectangular→superrectangular to equatorially-constricted. 2.Pollen grains of Hydrocotyloideae are mostly ellipsoidal with P / E ratio
1.07-1.6, the polar axis 22.5-46μm long, the equatorial axis 13.75-27.5μm long, and with
the size index 21.1-31.8.They are angulapeturate in the great majority, and the exine sculpture is recticulate under SEM. Those of Saniculoideae are mostly superrectangular or rectangular, with P/E ratio 1.3-2.1, the polar axis 35-65μm long, the equatorial axis 17.5-42.5μm long, and with the size index 28.2-49.7. They are planaperturate in the great majority and the exine sculpture is striate-reticulate or cerebro-reticulate under SEM. Therefore,
the latter might be more advanced than the former. 3.Pollen grains of Dickinsia Franch., endemic to China, are ellipsoidal,with P/E ratio 1.5,the polar axis 31.25-37.5μm long, the
equatorial axis 20-25μm, and with the size index 27.81. They are angulaperturate, and the
exine sculpture is cerebroid-reticulate under SEM. The genus is greatly similar to the members of Hydrocotyloideae in pollen morphology, which supports the treatment of the genus asa member of Hydrocotyloideae by Handel-Mazzetti (1933). |
