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POLLEN TUBE GROWTH WITHIN VEGETATIVE TISSUES OF CALLITRICHE (CALLITRICHACEAE)
Author(s) -
Philbrick C. Thomas
Publication year - 1984
Publication title -
american journal of botany
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.218
H-Index - 151
eISSN - 1537-2197
pISSN - 0002-9122
DOI - 10.1002/j.1537-2197.1984.tb14154.x
Subject(s) - biology , pollen , botany , stamen , pollen tube , pollination , vegetative reproduction , ovary , germination , rosette (schizont appearance) , double fertilization , apex (geometry) , sexual reproduction , immunology , endocrinology
Unisexual flowers of Callitriche heterophylla and C. palustris are of two types based on the degree to which they develop. Morphologically underdeveloped but functionally mature flowers occur on stems that grow completely submerged or stranded out of water. Under such conditions sexual reproduction is very unusual; pollen grains germinate in the intact anther and the pollen tubes grow down the filament, through vegetative tissue across to the pistillate flower and up into the ovary from the base. Pollen tubes may also grow through vegetative tissue to pistillate flowers across the stem at the same node, and up the stem from the staminate flowers at one node to pistillate flowers above. Morphologically mature flowers develop on stems when they reach the water surface and a floating rosette of leaves forms. In these flowers fertilization can take place via pollen tube growth through vegetative tissue as described above, or in the manner usually ascribed to angiosperms. Thus, depending upon the developmental form of the flower, fertilization takes place either with or without pollination. The current report represents the first description of pollen tubes traversing large segments of vegetative tissue within a plant to effect selffertilization.