Evolution 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. They are therefore often called microspecies. In some genera, it is possible to identify and name hundreds or even thousands of microspecies, which may be grouped together as species aggregates, typically listed in floras with the convention "Genus species agg." (such as the bramble, Rubus fruticosus agg.). In some plant families, genera with apomixis are quite common, for example in Asteraceae, Poaceae, and Rosaceae. 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 reported to occur in about 10% of globally extant ferns. Among polystichoid ferns, apomixis evolved several times independently in three different clades.
EvOLutiON 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. tHEY aRE tHerEfORe oFten caLled miCRospecIEs. in some gEnErA, iT is poSSiblE to identiFy ANd naMe HUndREds or eveN tHOusANds of mIcrospecieS, Which may bE grouped toGethEr aS sPecies aggrEgatEs, typicallY listeD IN fLorAs wiTh the COnVeNtioN "GenuS sPecIES aGg." (suCH As tHE BramblE, ruBus frUticosus agg.). iN sOMe plaNT families, genera wIth apOMIxis are quItE CoMmOn, for ExamPle in AsterAcEAe, poaceaE, aNd roSAceAe. 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 rEpoRted To occur IN ABOut 10% of GlObaLly Extant ferns. among PoLysTichOid fernS, aPOMIxIs eVOLved several times independentlY in tHREe diFfereNT cLades.