Скачать или смотреть Cleistogamy & geitonogamy

∆ Cleistogamy is a type of self-pollination where a flower remains permanently closed, and pollination occurs internally without the need for external pollinators. This process ensures reproduction under unfavorable conditions but leads to reduced genetic variation.

• Examples of cleistogamous flowers are found in plants like the grass family, peas and peanuts.

Key characteristics

✓ Closed flowers: Cleistogamous flowers remain permanently closed, so their reproductive parts are never exposed.

✓ Self-pollination (autogamy): Pollination occurs inside the unopened flower. Pollen from the anthers is transferred directly to the stigma of the same flower.

✓ Non-showy petals: Because they do not need to attract external pollinators, these flowers have small, inconspicuous, and often colorless petals.

✓ Synchronized maturation: The anthers and stigma mature at the same time and are located very close to each other inside the bud.

✓ Assured seed set: The enclosed structure guarantees that pollination and fertilization will occur, producing seeds even when pollinators are unavailable.

✓ Energy efficiency: Plants save the energy and resources that would otherwise be used to develop showy petals, nectar, and large quantities of pollen to attract pollinators.

• Plants that exhibit cleistogamy include peas, peanuts, and violets, as well as many grasses, such as barley and oats. Many plants, like those in the Commelina and Oxalis genera, produce both cleistogamous (closed) and chasmogamous (open) flowers.


∆ Geitonogamy is the transfer of pollen from one flower to another flower on the same plant, which is considered a type of self-pollination, although it functionally resembles cross-pollination because it requires a pollinating agent like wind or animals. This process results in genetically similar offspring, much like autogamy (self-pollination within the same flower).


Key characteristics

✓ Process: Pollen is transferred from the anther of one flower to the stigma of another flower on the same plant.

✓ Pollinating agents: It depends on external agents like wind or pollinators (e.g., insects, birds) to move the pollen, making it functionally similar to cross-pollination.

✓ Genetic outcome: Genetically, it is identical to self-pollination because the pollen and stigma belong to the same individual, leading to less genetic diversity in the offspring.

• Plants that exhibit geitonogamy

1. Monoecious plants: Plants that have both male and female flowers on the same individual, such as maize, often exhibit geitonogamy.

2. Plants with unisexual flowers: These plants are also susceptible to geitonogamy because they have separate male and female flowers on the same plant.

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