Yuccas are pollinated by the yucca moth. A nice introduction to this is given in this article: http://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/yucca_moths.shtml.
Just as there are many species of yucca, there are three genera and many species of the yucca moth. One genus, Tegeticula, is shown in this article with twenty species: http://en.wikipedia.org/wiki/Tegeticula. Another genus is Parategeticula. And there is a genus of false yucca moths, Prodoxus: http://pdfsb.com/yucca+moth+manual.
Side bar: In my own garden in Michigan I have many Yucca filamentosa, which are pollinated by the Tegeticula yuccasella. Y. filamentosa is classified as native or naturalized here, depending on what source of information you are reading. In any case, every year there is a period of intense yucca moth activity, some of which I have photographed and posted here: http://www.flickr.com/photos/mikesmode/sets/72157625733198704/detail/.
The National Center for Biotechnology Information has two abstracts on its web site that touch on the subjects of hybridization of yucca in nature and their pollinators:
- Abstract #1 entitled “Asymmetric hybridization and gene flow between Joshua trees (Agavaceae: Yucca) reflect differences in pollinator host specificity” located here: http://www.ncbi.nlm.nih.gov/pubmed/23190404.
- Abstract #2 entitled “Limiting cheaters in mutualism: evidence from hybridization between mutualist and cheater yucca moths” located here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1559949/
The full publications are available for download from the NCBI web pages listed above.
blog: [ M Hector ] 