facultative xenogamy, plant mating systems, thrips pollination, Verbena
Because their flowers can be cross- and/or self-pollinated Verbena stricta, V hastata and V urticifolia are facultatively xenogamous. We suggest the flowers can be cross-pollinated because I) the fruit set of caged plants was substantially lower than that of open-pollinated plants, i.e. pollinators were necessary for typical fruit set and 2) the flowers of each species attracted a diverse array of hymenopteran, dipteran and lepidopteran pollinators that were capable of moving pollen between plants. Self-pollination was low due to the spatial separation of anthers and stigmas and/or an angled corolla that decreased the likelihood of pollen dropping from the anthers onto the stigma. However, the limited ability of flowers to self-pollinate was supplemented by the intrafloral movement of pollen by thrips. In addition, both the pollen-ovule ratios and pollination efficiencies of these species were consistent with those of other facultatively xenogamous species, and the available data were consistent with each species being self-compatible. Finally, we discuss a protocol for distinguishing between self-pollination and the intrafloral movement of pollen by thrips.
Journal of the Iowa Academy of Science
© Copyright 1990 by the Iowa Academy of Science, Inc.
Cruden, Robert W.; Baker, Kristina K.; Cullinan, Thomas E.; Disbrow, Karen A.; Douglas, Kelly L.; Erb, John D.; Kirsten, Kenneth J.; Malik, Mary L.; Turner, Elizabeth A.; Weier, Jonathon A.; and Wilmot, Sherry R.
"The Mating Systems and Pollination Biology of Three Species of Verbena (Verbenaceae),"
Journal of the Iowa Academy of Science: JIAS: Vol. 97:
, Article 15.
Available at: http://scholarworks.uni.edu/jias/vol97/iss4/15