Hesperoyucca whipplei is pollinated solely by the California yucca moth (Tegeticula maculata), and the California yucca moth larvae feed only on developing seeds of H. whipplei: it’s an exclusive mutualistic relationship between yucca and moth, so if one of them die out the other one will also go extinct.
This is how it goes: The female moth works her magic at night time. She collects pollen from the stamens of the H. whipplei flowers, and rolls the pollen into a ball, and then she carries this ball with her as she finds a different flower. Here she lays her egg inside the flower’s pistil, before finally she inserts the ball of pollen into the stigmatic opening, pushing it down as far as she can. As a result the flower is pollinated and will develop seeds. That’s good planning because after it hatches, the California yucca moth larva feeds on some of these seeds. (Is it planning? I don’t know …evolution language is tricky.) But the larva won’t need all the seeds one flower produce, so there are many left to give the plant a good chance at propagating successfully.
Voilà, a new generation of moths and a new generation of chaparral yucca is on its way, supporting each other’s survival.
(I have written more about H. whipplei here.)
Other yuccas have similar symbiotic relationships with different species of yucca moths. The iconic Joshua tree — Yucca brevifolia — for instance, is pollinated by Tegeticula synthetica, whose larvae only feed on Joshua tree seeds.
Bibliography
- Kropotkin, Peter. Mutual Aid: A Factor of Evolution. New York: McClure, Phillips & Co., 1902.
- Riley, C.V. “The Yucca Moth and Yucca Pollination.” In Missouri Botanical Garden Annual Report Vol. 1892 (1892), pp. 99-158.
- Rundel, Philip W., and Robert Gustafson. Introduction to the Plant Life of Southern California : Coast and Foothills. Berkeley: University of California Press, 2005.