Expansion of female sex organs in response to prolonged virginity in Cannabis sativa (marijuana)
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Female flowers of Cannabis sativa in wild-growing populations and in hemp plantations are almost always well supplied with pollen. The style-stigma portion of the pistils of such plants was found to average only about 3 mm in length and to invariably be two-branched. By contrast, “buds” (congested female inflorescences), the standard form of marijuana now produced in the illicit and medicinal marijuana sectors, are protected against pollen. This report documents that in the absence of pollen, the style-stigma parts of virgin pistils expand notably, average over 8 mm in length, and tend to develop more than two branches and to increase in girth. From an evolutionary viewpoint, this expansion of pollen-receptive tissue is an apparent adaptation for increasing the probability of fertilizing the females when males are extremely scarce. From a practical viewpoint, the expanded presence of stigma tissues may be both advantageous and disadvantageous. The high-THC secretory gland heads of Cannabis tend to fall away from marijuana buds, significantly decreasing pharmacological potency, but many gland heads become stuck to the receptive papillae of the stigmas, reducing the loss. Although stigmas constitute a small proportion of marijuana, their distinctive chemistry could have health effects.
KeywordsCannabis sativa Hemp Marijuana Pollination Stigmas Styles
We thank Brenda Brookes and Tanya Antle for technical assistance.
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