Pollen-ovule Ratios in Milkweeds (Asclepiadaceae): an Exception that Probes the Rule

@inproceedings{Wyatt2000PollenovuleRI,
  title={Pollen-ovule Ratios in Milkweeds (Asclepiadaceae): an Exception that Probes the Rule},
  author={Robert E. Wyatt and Steven B. Broyles and Sara R. Lipow},
  year={2000}
}
Abstract Unlike most highly outcrossing flowering plants, milkweeds (Asclepiadaceae) have exceptionally low pollen-ovule ratios. We counted the number of pollen grains contained within a pollinium sac and the number of ovules contained within an ovary for 38 species of Asclepiadaceae. Across four tribes of the Asclepiadoideae, the number of pollen grains per pollinium varied from 14 to 445, and the number of ovules per ovary varied from 4 to 229. Nevertheless, the pollen-ovule ratio was… Expand
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