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Meiogyne (Annonaceae) comprises 15 species of trees and shrubs distributed in India, Indomalaya and Australasia–Pacific. Previous molecular phylogenetic analyses, based on limited taxon sampling, have indicated that the small genus Fitzalania (2 spp.) is nested within Meiogyne. The centre of diversity of the Meiogyne–Fitzalania group lies in Australia (6 spp.) and New Caledonia (4 spp.); this is unique in Annonaceae, some of whose Australian and New Caledonian lineages have been hypothesised to have originated in situ from Gondwanan ancestors. Phylogenetic reconstructions based on chloroplast DNA sequence data of 19 accessions, representing 14 of the 17 species in the Meiogyne–Fitzalania group (ca. 8.6 kb) as well as 67 representatives of all major clades of Annonaceae (ca. 5.1 kb), were performed to clarify the phylogenetic relationships of Meiogyne and Fitzalania. The results show that Fitzalania is deeply nested within an Australasian–Pacific clade of Meiogyne species. The inclusion of species assigned to Chieniodendron and Oncodostigma in Meiogyne, as proposed in the most recent revision of Meiogyne, is also corroborated. Fossil–calibrated molecular divergence estimates under an uncorrelated–rates relaxed molecular clock model were used to investigate the timing of the crown group diversification. The Meiogyne crown group was inferred to have originated in the late Oligocene or Miocene, and initially diversified in continental Southeast Asia, western Malesia and the Philippines. All Australasian–Pacific taxa formed a single derived clade, and most diversification within this clade occurred in the late Miocene and Pliocene. A complex combination of factors such as fragmentation of once wider distribution areas due to climate fluctuations and subsequent vicariance, range expansion by dispersal to Pacific islands and subsequent differentiation, and ecological adaptation to local climatic and edaphic habitat conditions is hypothesised to underlie the diversification of Meiogyne in Australasia and the Pacific.

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Spiranthes (∼36 species, Orchidaceae) is a small genus with a global distribution. It has a center of diversity in North America with only a few species occurring in Asia. This study focuses on the Asian Spiranthes with an emphasis on understanding their biogeographic relationships and species delimitations using molecular markers. Our phylogenetic trees based on nuclear (ITS) and chloroplast (trnL-trnLF, matK and trnS-G) sequences from samples across their range in Asia revealed the Asian Spiranthes are monophyletic. Ancestral area optimization suggested that North America forms the ancestral region for the Asian Spiranthes rather than Europe suggesting that they originated from a single long-distance dispersal event. Our study also revealed the presence of a cryptic species S. himalayensis, which was discovered based on molecular data thus emphasizing the importance of wide geographical sampling in phylogenetic studies. Sequences of cloned ITS provided support for the hypothesis that natural hybridization between S. sinensis and the newly described S. himalayensis resulted in the allotetraploid S. hongkongensis, with S. himalayensis as the paternal parent. One of the species complexes known in Asia is the S. sinensis complex, which shows a wide occurrence and is known for local geographical variants. Some of these variants have been described as new species in Australia and New Zealand. Our studies show that all the sampled variants including the Australian and New Zealand species show monophyly despite having long branches. This suggests that there may be high rates of gene flow between the geographically distinct forms resulting in lack of species resolution within the S. sinensis complex.