Everything about Apomict totally explained
In
botany,
apomixis (also called
apogamy) is
asexual reproduction, without fertilization. In plants with independent gametophytes (notably ferns), apomixis refers to the formation of sporophytes by parthenogenesis of gametophyte cells. Apomixis also occurs in flowering plants, where it's also called
agamospermy. Apomixis in flowering plants mainly occurs in two forms: In
agamogenesis (also called
gametophytic apomixis), the
embryo arises from an unfertilized egg that was produced without meiosis. In
adventitious embryony, a
nucellar embryo is formed from the surrounding nucellus tissue. Apomictically produced
seeds are genetically identical to the parent plant.
As apomictic plants are genetically identical from one generation to the next, each has the characters of a true
species, maintaining distinctions from other
congeneric apomicts, while having much smaller differences than is normal between species of most
genera. They are therefore often called
microspecies. In some genera, it's possible to identify and name hundreds or even thousands of microspecies, which may be grouped together as
aggregate species, typically listed in
Floras with the convention "
Genus species agg." (for example, the
bramble,
Rubus fruticosus agg.). Examples of apomixis can be found in the genera
Crataegus (hawthorns),
Amelanchier (shadbush),
Sorbus (
rowans and
whitebeams),
Rubus (brambles or blackberries),
Hieracium (
hawkweeds) and
Taraxacum (
dandelions). Although the
evolutionary advantages of
sexual reproduction are lost, apomixis does pass along traits fortuitous for individual evolutionary fitness.
A unique example of
male apomixis has recently been discovered in the Saharan Cypress,
Cupressus dupreziana, where the seeds are derived entirely from the
pollen with no genetic contribution from the female "parent" (Pichot, et al., 2000, 2001).
Further Information
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