SIZES OF NATURAL MICROGAMETOPHYTE POPULATIONS IN PISTILS OF PHLOX DRUMMONDII |
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Authors: | Donald A Levin |
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Institution: | Department of Botany, University of Texas, Austin, Texas, 78713 |
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Abstract: | The numbers of microgametophytes in the stigmas of the outcrossing Phlox drummondii were determined in 19 natural populations. Microgametophyte numbers per stigma ranged from 0 to over 40 in each population. The number of flowers per plant, distance to the nearest-neighbor, and number of plants within 1 m of the focal plants explained about 23% of the variation in microgametophyte numbers within 2 of the populations. The mean number per stigma across all populations was 14.34; and the mean number per population varied from 7.77 to 19.52. Given that there are 3 ovules per flower, there was an average of 4.73 microgametophytes per ovule. Sixty-nine percent of all pistils contained more than 3 microgametophytes, thereby presenting an opportunity for intergametophytic competition. |
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