Malpighiales
Background
Malpighiales (rosids; fabids) are one of the few orders in the Angiosperm Phylogeny Group classification that is entirely new in its composition. It unites 28–37 plant families with about 700 genera and 16,000 species. Its members were formerly placed in Linales, Theales, Polygalales, Geraniales, Rosales, Malvales and several others (Angiosperm Phylogeny Group (APG) 2003. An update of the APG classification for the orders and families of flowering plants: APG II. Bot.J.Linnean>Soc. 141: 399-436. See also www.mobot.org/MOBOT/Research/APWeb). The largest families are Euphorbiaceae sensu stricto, Phyllanthaceae, Clusiaceae, Malpighiaceae, Salicaceae sensu lato (including willows and poplars) and Violaceae (including violets and pansies). Others include Erythroxylaceae (including the coca plant), Linaceae (including flax), Passifloraceae (passion flowers), Rafflesiaceae (including the world’s largest flower, Rafflesia arnoldii) and Rhizophoraceae (including mangroves). Traditionally, these families would not have been considered close relatives. Basal nodes in the phylogenetic tree of the order are poorly supported despite data from all three genomes (chloroplast, mitochondrial and nuclear) having been analysed; relationships between the constituent clades remain largely unresolved. Among the most surprising results is the position of the hitherto unplaced, highly modified aquatic Podostemaceae close to woody Clusiaceae, the strongly supported relationship of Erythroxylaceae and Rhizophoraceae, and the recent inclusion of holoparasitic Rafflesiaceae in Malpighiales without supported sister relationship. The order also contains the two largest polyphyletic traditional plant families: Euphorbiaceae sensu lato (now Centroplacaceae, Euphorbiaceae sensu stricto, Pandaceae, Phyllanthaceae, Picrodendraceae and Putranjivaceae) and Flacourtiaceae (now Achariaceae sensu lato and Salicaceae sensu lato).