Parsimony analyses of morphology, restriction sites of the cpDNA, sequences from the nuclear, ribosomal internal transcribed spacer (ITS), and the chloroplast gene rbcL were performed to asses tribal and generic relationships in the subfamily Ixoroideae (Rubiaceae). The tribes Vanguerieae and Alberteae (Antirheoideae) are clearly part of Ixoroideae, as are some Cinchonoideae taxa. Pavetteae should exclude Ixora and allies, which should be recognized as the tribe Ixoreae. Heinsenia, representing Aulacocalyceae, is part of Gardenieae, as is Duperrea, a genus earlier placed in Pavetteae. Posoqueria and Bertiera and the taxa in the subtribe Diplosporinae should be excluded from Gardenieae. Bertiera and three Diplosporinae taxa are part of Coffeeae, while Cremaspora (Diplosporinae) is best housed in a tribe of its own, Cremasporeae. The mangrove genus Scyphiphora, recently placed in Diplosporinae, is closer to Ixoreae and tentatively included there. The combined analysis resulted in higher resolution compared to the separate analyses, exemplifying that combined analyses can remedy the incapability of one data set to resolve portions of a phylogeny. Twenty-four new rbcL sequences representing all five Ixoroideae tribes (sensu Robbrecht) are presented.

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Heterogeneous DNA substitution rates were found in the 18S-26S nuclear ribosomal DNA internal transcribed spacer (ITS) and external transcribed spacer (ETS) regions of Sidalcea (Malvaceae), a putatively young genus of annuals and perennials. The majority of comparisons revealed that the annual species had significantly higher molecular evolutionary rates than the perennials, whereas rates were consistently homogenous between obligate annual species. These findings led us to conclude that generation time or possibly another biological factor distinguishing annuals and perennials has influenced rates of molecular evolution in SIDALCEA: The congruence of relative-rate test results across both spacer regions reinforced the association between life history and rate of rDNA evolution across lineages of checker mallows. Evolutionary rate variation within perennials mainly involved three basally divergent lineages. The faster rate in one lineage, Sidalcea stipularis, compared with other perennials may be the result of genetic drift in the only known, small, population. The other two basally divergent lineages had slower evolutionary rates compared with the remaining perennials; possible explanations for these differences include rate-reducing effects of a suffrutescent (rather than herbaceous) habit and seed dormancy.

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