On the pollination mechanism of some eurysaline potamogetonaceae

Abstract

The pollination mechanism in three eurysaline Potamogetonaceae was studied. These species were Zannichellia peltata Bertol., Ruppia megacarpa Mason and Lepilaena cylindrocarpa (Koernicke ex Walp.) Benth. In Zannichellia peltata pollination occurs underwater. When Ruppia megacarpa flowers, the pollen is released at the water surface and floats in clumps and the stigmata come in close contract with the floating clumps. The flowers are situated at the end of a fast-growing peduncle which spiralizes after flowering. As a consequence, the fruits develop underwater. In Lepilaena cylindrocarpa pollination also occurs at the water surface. Here, the stigmata are in close contact with the water surface. The anther is released from its peduncle and rises to the water surface where it dehisces and releases its floating pollen. The clumps of pollen are attracted by the somewhat depressed water surface around the neighbouring stigmata.