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Q.
Maturation of both androecium and gynoecium at the same time is called
NTA AbhyasNTA Abhyas 2020
Solution:
Plants have several contrivances for both Autogamy like:
Homogamy refers to the maturation of both, male and female reproductive organs at the same time, which is also known as simultaneous or synchronous hermaphrodism. Many flowers appear to be homogamous but may not be strictly functionally homogamous because male and female reproduction do not overlap. It can be used as a form of choosing a mate based on the characteristics wanted in a sexual partner. In flowers, homogamy is characterised by simultaneous maturation of anther and stigma. Self-pollination causes homozygosity; i.e, the same set of genes are received from each parent leading to possession of two exact forms of the same gene. Cleistogamy is a type of automatic self-pollination, supported or characterised by non-opening, self-pollinating flowers. This behaviour is widespread amongst grasses and largest genus of cleistogamous flowers is Viola. In cleistogamous flowers, the anther and stigma are close to each other and anther dehiscence and stigma receptivity is synchronised. Thus, cleistogamous flowers produce assured seed-set even in the absence of pollinators. Monocliny is the phenomenon of producing bisexual flowers, i.e, Both male and female reproductive parts are present in the same flower. Such flowers are also called hermaphrodite. But certain features such as non-synchrony in the maturation of the androecium and gynoecium, the difference in their position and arrangement, or incompatibility of self pollen, are some out-breeding devices to prevent self-pollination.
On the other hand, some common contrivances for allogamy like
Herkogamy is a strategy deployed by hermaphrodite angiosperms to reduce the sexual interference between androecium and gynoecium. Two forms of herkogamy are-
Approach herkogamy- In bisexual flowers, anther is placed below the stigma so that upon dehiscence, the pollen does not come in contact with the stigma, or the pollinators come in contact with the stigma before removing anther from pollen. This is a common feature to prevent in-breeding.
Reverse herkogamy- In this type of herkogamy, stigma is placed below the anther. This type of herkogamy facilitates greater pollen export than the former. This arrangement is common amongst Lepidopteran pollination.