Pollen morphology of 79 species, one subspecies and eight varieties representing nine genera of tribe Alsineae and two of tribe Sperguleae was studied using light microscopy (LM) and scanning electron microscopy (SEM). Among them, 53 species and eight varieties (22 species of which are endemic to China) were reported for the first time. The results demonstrate that the number of pores, the pollen surface ornamentation and the density of microechini have important systematic significance. The surface ornamentation can be divided into three types, namely microechinate-perforate, microechinate-punctate, and microechinate-punctate-perforate. Pollen characteristics support: (i) isolation of Arenaria subgenus Odontostemma from Arenaria and reclassification of Arenaria subgenus Odontostemma to Odontostemma; (ii) isolation of Cerastium subgenus Dichodon from Cerastium and reclassification of Cerastium subgenus Dichodon to Dichodon; (iii) isolation of Minuartia subgenus Rhodalsine from Minuartia and reclassification of Minuartia subgenus Rhodalsine to Rhodalsine; (iv) isolation of Rhodalsine from tribe Alsineae and reclassification of Rhodalsine into tribe Sperguleae; and (v) isolation of Sagina from tribe Alsineae. In addition, the relationships of Arenaria subgenus Eremogone and Arenaria subgenus Eremogoneastrum to tribe Alsineae need to be further studied. Furthermore, pollen characteristics indicate that tribe Alsineae is more evolved than tribe Sperguleae.

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