Prunus subg. Prunus is a subgenusofPrunus. This subgenus includes plums, apricots and bush cherries. Some species conventionally included in Prunus subg. Amygdalus are clustered with plum/apricot species according to molecular phylogenetic studies.[1][2] Shi et al. (2013) has incorporated subg. Amygdalus into subg. Prunus, thereby including almonds and peaches in this subgenus.[1] The species in this subgenus have solitary flowers or 2–3 in a fascicle.[1][3]
Shi et al. (2013) divide subg. Prunus into seven sections: sect. Amygdalus, sect. Armeniaca, sect. Emplectocladus, sect. Microcerasus, sect. Persicae, sect. Prunocerasus and sect. Prunus. They form three clades. The basal clade is sect. Emplectocladus which is sometimes treated as a subgenus. The other two clades are the Amygdalus-Persicae clade (sometimes treated as subg. Amygdalus) and the Armeniaca-Microcerasus-Prunocerasus-Prunus clade (subg. Prunus in a narrow sense).[1]
Prunus sect. Emplectocladus (Torr.) A.Gray is the sister group to all the other species in this subgenus,[1] and sometimes treated as a distinct subgenus, Prunus subg. Emplectocladus (Torr.) S.C.Mason. It includes six New World species.[4][5]
Prunus sect. Amygdalus (L.) Benth. & Hook.f. and the next section (Persica) sometimes constitute Prunus subg. Amygdalus (L.) Focke which is monophyletic, but the incongruence between nuclear and chloroplast DNA phylogenies blurs the boundary between the two sections somewhat.[2][6] The word『ămygdălus』is Latin for the almond nut.[7]
Prunus sect. Persica (Mill.) Nakai[a] includes peach species[8] as well as two species previously considered almonds (P. mongolica and P. tangutica).[2]
Species of the following sections were not presented in the results of Shi et al. (2013). Therefore, their relationship with the sections proposed by Shi et al. (2013) is unclear.
Prunus sect. Chamaeamygdalus (Spach) Dippel used to be included in the Amygdalus-Persica clade. However, molecular phylogenetic research indicates that it should be excluded from the Amygdalus-Persica clade.[2] The phylogenetic positions of the species in this section are still uncertain.
Prunus sect. Louiseania (Carrière) Yazbek includes two or three Asian species.[9] They are called flowering almond and morphologically close to wild almonds (sect. Amygdalus),[2] but they are more related to bush cherries (sect. Microcerasus) and apricots (sect. Armeniaca).[2][6][10][11][12][13][14][15][16] According to nuclearphylogenomic analyses, the type species of sect. Louiseania, P. triloba, is embedded in sect. Microcerasus and closely related to the P. prostrata, the type species of sect. Microcerasus. However, in the phylogenetic tree based on plastid genome, P. triloba together with P. tomentosa (also a member of sect. Microcerasus) and apricots is in a clade that is sister to the core part of sect. Microcerasus.[14][16] The incongruity is attributable to multiple hybridization events during the speciation of P. triloba, which probably involves species of sect. Amygdalus, sect. Armeniaca, sect. Microcerasus, sect. Prunus, and even subg. Cerasus.[14]
Prunus sect. Penarmeniaca S.C.Mason is the sister group to the New World section Prunocerasus and probably the Old World species P. tenella.[2] It includes two New World species.[4][17]
