Apomixis

apomicticapogamyagamospermyapomictic microspeciesapogamousandrogenesisapomictagamospeciesapogamouslyapomictically
In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization.wikipedia
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Plant reproduction

reproductionbisexualsexual reproduction
Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis.
a vegetative piece of the original plant (budding, tillering, etc.) and is distinguished from apomixis, which is a replacement for sexual reproduction, and in some cases involves seeds.

Parthenogenesis

parthenogeneticparthenogenicparthenogenetically
In plants with independent gametophytes (notably ferns), the term is still used interchangeably with "apomixis", and both refer to the formation of sporophytes by parthenogenesis of gametophyte cells.
In plants parthenogenesis is a component process of apomixis.

Cloning

cloneclonescloned
In flowering plants, the term "apomixis" is commonly used in a restricted sense to mean agamospermy, i.e. clonal reproduction through seeds.
The term clone is used in horticulture to refer to descendants of a single plant which were produced by vegetative reproduction or apomixis.

Rowan

rowan treeSorbusmountain ash
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
They are native throughout the cool temperate regions of the Northern Hemisphere, with the highest species diversity in the mountains of western China and the Himalaya, where numerous apomictic microspecies occur.

Whitebeam

AriawhitebeamsCommon Whitebeam
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
They are related to the rowans (Sorbus subgenus Sorbus), and many of the endemic restricted-range apomictic microspecies of whitebeam in Europe are thought to derive from hybrids between S. aria and the European rowan S. aucuparia; some are also thought to be hybrids with the wild service tree S. torminalis, notably the service tree of Fontainebleau Sorbus latifolia in French woodlands.

Amelanchier

serviceberryshadbushserviceberries
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
A major source of complexity comes from the occurrence of hybridization, polyploidy, and apomixis (asexual seed production), making species difficult to characterize and identify.

Asexual reproduction

asexualasexuallyreproduce asexually
In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization.
Examples are parthenogenesis and apomixis.

Botany

botanistbotanicalplant biology
In botany, apomixis was defined by Hans Winkler as replacement of the normal sexual reproduction by asexual reproduction, without fertilization.
This is one of several types of apomixis that occur in plants.

Rosaceae

rose familyrosaceousroses
In some plant families, genera with apomixis are quite common, for example in Asteraceae, Poaceae, and Rosaceae.
Compounding the problem is that apomixis is common in several genera.

Polystichum

Native sword fernspolystichoidPolystichum fuentesii
Among polystichoid ferns, apomixis evolved several times independently in three different clades.
Apomixis, the development of an embryo without the occurrence of fertilization, is particularly common among ferns.

Sorbus

mountain ashashashberries
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
The exact number of species is disputed depending on the circumscription of the genus, and also due to the number of apomictic microspecies, which some treat as distinct species, but others group in a smaller number of variable species.

Species

specificspecific namespecific epithet
Because apomictic plants are genetically identical from one generation to the next, each lineage has some of the characters of a true species, maintaining distinctions from other apomictic lineages within the same genus, while having much smaller differences than is normal between species of most genera.
When organisms reproduce asexually, as in single-celled organisms such as bacteria and other prokaryotes, and parthenogenetic or apomictic multi-celled organisms. The term quasispecies is sometimes used for rapidly mutating entities like viruses.

Species complex

species groupsuperspeciescryptic species
They are therefore often called microspecies.
Also, asexual reproduction, such as through apomixis in plants, may separate lineages without producing a great degree of morphological differentiation.

Plantlet

plantlets
Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis.
Apomixis

Rubus

blackberriesbramblesblackberry
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
As Rubus species readily interbreed and are apomicts (able to set seed without fertilisation), the parentage of these plants is often highly complex, but is generally agreed to include cultivars of blackberries, (Rubus ursinus, R. fruticosus) and raspberries (R. idaeus).

Bulb

bulbousbulbsbulbous plants
Thus "normal asexual reproduction" of plants, such as propagation from cuttings or leaves, has never been considered to be apomixis, but replacement of the seed by a plantlet or replacement of the flower by bulbils were categorized as types of apomixis.
Several members of the onion family, Alliaceae, including Allium sativum (garlic), form bulbils in their flower heads, sometimes as the flowers fade, or even instead of the flowers (which is a form of apomixis).

Meiosis

meioticsyzygymeiosis I
This definition notably does not mention meiosis.
Apomixis

Asteraceae

daisy familysunflower familydisc floret
In some plant families, genera with apomixis are quite common, for example in Asteraceae, Poaceae, and Rosaceae.
Many members of Asteraceae are pollinated by insects, which explains their value in attracting beneficial insects, but anemophily is also present (e.g. Ambrosia, Artemisia). There are many apomictic species in the family.

Citrus

citrus fruitcitrus fruitscitrus juice
Adventive embryony, also called sporophytic apomixis, sporophytic budding, or nucellar embryony: Here there may be a megagametophyte in the ovule, but the embryos do not arise from the cells of the gametophyte; they arise from cells of nucellus or the integument. Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis, Mangifera indica etc.
The taxonomy and systematics of the genus are complex and the precise number of natural species is unclear, as many of the named species are hybrids clonally propagated through seeds (by apomixis), and genetic evidence indicates that even some wild, true-breeding species are of hybrid origin.

Taraxacum

dandeliondandelionsdandelion greens
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
Many Taraxacum species produce seeds asexually by apomixis, where the seeds are produced without pollination, resulting in offspring that are genetically identical to the parent plant.

Garcinia

saptreeasam kandisGarcinia (''Garcinia gummi-gutta'')
Adventive embryony, also called sporophytic apomixis, sporophytic budding, or nucellar embryony: Here there may be a megagametophyte in the ovule, but the embryos do not arise from the cells of the gametophyte; they arise from cells of nucellus or the integument. Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis, Mangifera indica etc.
Garcinia species are evergreen trees and shrubs, dioecious and in several cases apomictic.

Crataegus

hawthornhawthornshawberries
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
Some botanists in the past recognised 1000 or more species, many of which are apomictic microspecies.

Nardus

matgrassmoor matgrassmat-grass
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
Apomixis is found to be common in this plant, with extensive colonies often proving to be a single clone.

Hieracium

hawkweedHieraciahawkweeds
Examples of apomixis can be found in the genera Crataegus (hawthorns), Amelanchier (shadbush), Sorbus (rowans and whitebeams), Rubus (brambles or blackberries), Poa (meadow grasses), Nardus stricta (Matgrass), Hieracium (hawkweeds) and Taraxacum (dandelions).
Since most hawkweeds reproduce exclusively asexually by means of seeds that are genetically identical to their mother plant (apomixis or agamospermy), clones or populations that consist of genetically identical plants are formed and some botanists (especially in UK, Scandinavia and Russia) prefer to accept these clones as good species (arguing that it is impossible to know how these clones are interrelated) whereas others (mainly in Central Europe and USA) try to group them into a few hundred more broadly defined species.

Cupressus dupreziana

See also androgenesis and androclinesis described below, a type of male apomixis that occurs in a conifer, Cupressus dupreziana.
Probably as a result of its isolation and low population, the Saharan cypress has evolved a unique reproductive system of male apomixis whereby the seeds develop entirely from the genetic content of the pollen.