Polystachya (Orchidaceae)

Evolutionary studies are usually based on dichotomously branching phylogenetic trees. Russell et al. (pp. 37–56) use DNA data from several plastid and low-copy nuclear genes to generate phylogenetic networks of Polystachya, showing reticulate evolution. One group of allotetraploid species has a recent history of long-distance dispersal and multiple hybrid origins; another shows considerable morphological diversity on Madagascar and the Comoros.