Cleistogamy or automatic self-pollination describes the trait of certain plants to propagate by using non-opening, self-pollinating flowers. Especially in peanuts, peas, and beans, this behaviour is most widespread in the grass family, though the largest genus of cleistogamous plants is actually Viola.
For genetically modified (GM) rapeseed, researchers hoping to minimise the admixture of GM and non-GM crops are attempting to use cleistogamy to prevent gene flow. However, preliminary results from Co-Extra, a current project within the EU research programme, show that although cleistogamy reduces gene flow, it is not at the moment a consistently reliable tool for biocontainment: due to a certain instability of the cleistogamous trait, some flowers may open and release genetically modified pollen.
The more common opposite of cleistogamy: "Closed-marriage", is called chasmogamy: "Open-marriage".
Source : http://en.wikipedia.org/wiki/Cleistogamy
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