Phylogenetic relationships in Buxaceae based on nuclear internal transcribed spacers and plastid ndhF sequences

Sequences of nuclear internal transcribed spacers (ITS) and plastid ndhF from 25 representatives of Buxaceae were analyzed separately and in combination to resolve phylogenetic relationships among and within genera; parsimony and maximum likelihood methods were used. The results of the two single-gene analyses were generally congruent, and the trees from the combined analysis were better supported. Two major clades were identified within the Buxaceae family: the clade of Pachysandra, Sarcococca, and Styloceras and the clade of Buxus and Notobuxus. Pachysandra and Sarcococca were two strongly supported monophyletic groups. The sister relationship between Sarcococca and the clade of Pachysandra and Styloceras was also strongly supported. American and Eurasian Buxus each formed a strongly supported clade. The controversial genus Notobuxus was embedded among African members of Buxus; B. hildebrandtii was sister to Notobuxus, with strong support. Relationships within Buxus and Sarcococca were only partially resolved.