Help—we're being invaded by myriads of strange creatures dropping from the sky. No, not aliens in flying saucers, but organisms so strange that many of us forget they're alive. Pollen of flowering plants fills the air, and each pollen grain represents a microscopic plant so small that it consists of only two living cells.
Not like any plant you've ever heard of? Well, here's your botany lesson for the day. Plants alternate generations between the plants we know and love with offspring, called gametophytes, so different as to be truly alien to our minds. It's as if our children looked like jellyfish, but our grandchildren were back to being like us.
The pollen grain encases the two-celled male gametophyte, while the
female of that generation, consisting of only seven cells, lies buried within the
flower. Upon lighting on the female parts, one of the male's two cells divides to
form two sperm which migrate to the female, fertilizing her and initiating the start of
the next generation—what you have always thought of as "the plant".
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.
Purves, W. K., D. Sadava, G. H. Orians, and H. C. Heller. 2001. Life, the Science of Biology. Sinauer Associates, Inc., Sunderland, MA. 1044 pp + unnumbered pp.
Palynology, University of Arizona