Geitonogamy

Geitonogamy (from Greek geiton (γείτων) = neighbor + gamein (γαμεῖν) = to marry) is a type of self-pollination.^[1] Geitonogamous pollination is sometimes distinguished from the fertilizations that can result from it, geitonogamy.^[2] If a plant is self-incompatible, geitonogamy can reduce seed production.^[3]

In flowering plants, pollen is transferred from a flower to another flower on the same plant, and in animal pollinated systems this is accomplished by a pollinator visiting multiple flowers on the same plant. Geitonogamy is also possible within species that are wind-pollinated, and may actually be a quite common source of self-fertilized seeds in self-compatible species.^[4] It also occurs in monoecious gymnosperms.^[5]

Empirical work shows that geitonogamy is seldom a marginal process: in many flowering plants it represents a sizeable share of all pollen transfer and its incidence rises steeply as the number of simultaneously open flowers on a plant increases. Field experiments and pollen-movement models indicate that a plant with ten open flowers may experience about 13% geitonogamous pollen receipt, whereas a display of fifty flowers can push that figure beyond 45%; at the same time, pollen export per flower drops sharply as self-delivery soaks up the grains that would otherwise reach neighbouring individuals.^[6]

Because pollen retained within the parent plant earns little or no male fitness and may interfere with female success, geitonogamy carries measurable costs. In self-incompatible species experimental precedence of self-pollen has reduced subsequent seed set by up to 40%, whereas in self-compatible taxa any level of inbreeding depression means that seeds sired through geitonogamy are, on average, less fit than outcrossed progeny. These effects are especially pronounced in large, many-flowered clones, helping to explain selection for traits—such as staggered flowering, directional nectar gradients or architectural arrangements that guide pollinators away from older female-phase flowers—that reduce successive visits to blossoms on the same individual.^[6]

See also

• Plant reproductive morphology
• Self-fertilization
• Autogamy Depression