The relationships among the members of the economically important subfamily Amygdaloideae (Rosaceae) are in need of a phylogenetic reappraisal. Sequences of the ITS regions of nrDNA and the ndhF gene of cpDNA were employed to reconstruct the phylogeny of the subfamily, and evaluate the traditional classification schemes of this group. The two data sets are congruent in several aspects: (1) the genera Prunus s.l. and Maddenia form a monophyletic group, with Maddenia being nested within Prunus; (2) Exochorda (traditionally placed in subfamily Spiraeoideae) is closely allied with the Amygdaloideae; (3) two major clades are recognizable within Prunus: one consisting of the subgenera Amygdalus and Prunus, and the other containing the subgenera Cerasus, Laurocerasus, and Padus (including Maddenia); and (4) a few members of the subgenus Cerasus (Prunus besseyi and P. tomentosa) are placed within the clade consisting of subgenera Amygdalus and Prunus, suggesting that subgenus Cerasus is polyphyletic. The two analyses differ in the placement of the core cherry group (subgenus Cerasus) and the position of Maddenia. The combined analysis has a higher resolution within Prunus and places Maddenia sister to Prunus s.l. Traditionally, Maddenia has been separated from Prunus because of the calyx lobes (10 as opposed to 5 in most Prunus) and unisexual flowers. This study suggests the need for further evaluation of the phylogenetic position of Maddenia.

Key words: Amygdaloideae, Prunus, Rosaceae, systematics, taxonomy