Pollination
Pollination could be
of two types: self- and cross-pollination. Cross-pollination
can happen in both abiotic and biotic ways. Abiotic would be represented by
gravity, wind, or water; biotic would be performed by agents like insects,
birds, bats, or in some cases tree mammals like possums. Wind-pollination is
seen as being wasteful and unintelligent due to the fact that the plant needs
to produce so much more pollen without any precise targeting.
Adaptation to the
particular pollination agent results in different pollination syndromes. For
example, cup-shaped flowers are usually pollinated with mas-sive animals like
beetles and even bats. Funnel-shaped flowers as well as labiate flowers (with
lips), are adapted to flies and bees. Flowers with long spurs attract
butterflies and birds (like hummingbirds or sugarbirds).
Self-pollination often
exists like a “plan B”, in case cross-pollination is, for some reason,
impossible. Sometimes, self-pollinated flowers even do not open; these flowers
are called cleistogamous.
If pollination needs
to be avoided, apomixis will prevent it. Apomixis
requires reproductive organs, but there is no fertilization. One type of
apomixis is apospory when an embryo
develops from the maternal diploid tissue, but does not go through the meiosis
stage. In this process, asexual reproduction will have be-come vegetative.
Another type of apomixis would be apogamy
(parthenogene-sis) when embryo develops from an unfertilized gamete after
diploidization has occurred. Here, vegetative reproduction evolved from sexual
reproduction.
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