[Plant-education] Re: Introductory Botany

Janice M. Glime jmglime at mtu.edu
Mon May 29 17:32:45 EST 2006

David raises the question of why dioecious plants don't have more asexual 
reproduction.  Perhaps they just aren't old enough.  In bryophytes, 
dioecious plants are more likely to have asexual reproduction than are 
monoecious ones.  Longton did an interesting study on reproduction and 
rarity in British mosses and found:

1.  a higher proportion of monoecious than of dioecious species is rare
2.  a higher proportion of species not known to produce sporophytes than 
species producing them is rare
3.  absence of sporophytes is more prevalent among dioecious than 
monoecious species
4.  a higher proportion of monoecious species producing sporophytes than 
of dioecious species is rare

Several recent studies have questioned the evolutionary benefits of 
sexual reproduction.

Longton, R. E.  1992.  Reproduction and rarity in British mosses.  Biol. 
Conserv. 59: 89-98.

  Janice M. Glime, Professor
  Department of Biological Sciences
  Michigan Technological University
  Houghton, MI 49931-1295
  jmglime at mtu.edu
  FAX 906-487-3167 

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