This purchase only includes chapter 18 of this title.
Cone thermogenesis and the production of volatile odors during the pollination period are almost ubiquitous in cycads. The incidence of both events at a time when insect pollinators are active has led to speculation about their functional role in cycad pollination. Most often, heating and odors are assumed to attract pollinators in the same way that they do in some ï¬‚owering plants. However, all the known cycad pollinators are phytophagous insects that mate, breed, and feed on cycads and have varying levels of host speciï¬?city within cycad genera. The function of cone thermogenesis and volatile odors therefore needs to be explained within the context of pollination systems that have evolved from cycadâ€“herbivore interactions in which insects may be preadapted to ï¬?nding their host plants and spending most of their life cycles associated with the host plant. In this paper, several possible models for the role of cone thermogenesis and volatile compounds in cycad pollination are given, with the expectations associated with each model. The limited available data indicate that these models are credible explanations of cycad pollination systems but are insufï¬?cient to refute or support any of the models.