Jan. 28, 2017

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Pussytoes are in the aster family.  That family has flower heads made up of many smaller individual flowers.  There are many pollination schemes among the species.  Some have both sexes in all flowers.  Some have some flowers in the same head that are separate sexes.  Some have the sexes in separate heads on the same plant.  And some like pussytoes have them on separate plants.  In the upper image, one can barely see the two-pronged white stigmas projecting from the finer bristles.  In the lower image, the anther tubes are easily visible because of the lack of bristles.  On both plants there in one pistil or stamen for each flower, and many flowers in each head.  This arrangement of separate sexes in plants assures cross pollination, which is believed to greater individual variation and stronger populations.  How then can we account for the fact that Parlin's pussytoes often shows up in entirely female populations, and those populations produce as much seed as others?  The female populations are able to produce seed asexually.  I'm guessing that a species that can employ both sexual and asexual reproduction has an advantage over other species.