Malpighiales

The Malpighiales comprise one of the largest orders of flowering plants. The order is very diverse, with well-known members including willows, violets, aspens and poplars, poinsettia, corpse flower, coca plant, cassava, flaxseed, castor bean, Saint John's wort, passionfruit, mangosteen, and manchineel tree.

The order is not part of any of the classification systems based only on plant morphology and the relationships of its diverse members can be hard to recognize except with molecular phylogenetic evidence. Molecular clock calculations estimate the origin of stem group Malpighiales at around 100 million years ago (Mya) and the origin of crown group Malpighiales at about 90 Mya.

The Malpighiales contain about 36 families and more than 16,000 species, about 7.8% of the eudicots.

The Malpighiales include the following 36 families, according to the APG IV system of classification:

In the APG III system, 35 families were recognized. Medusagynaceae, Quiinaceae, Peraceae, Malesherbiaceae, Turneraceae, Samydaceae, and Scyphostegiaceae were consolidated into other families. The largest family, by far, is the Euphorbiaceae, with about 7500 species in about 300 genera. Changes made in the Angiosperm Phylogeny Group (APG) classification of 2016 (APG IV) were the inclusion of Irvingiaceae, Peraceae, Euphorbiaceae and Ixonanthaceae, together with the transfer of the COM clade from the fabids (rosid I) to the malvids (rosid II).

The phylogenetic tree shown below is from Xi et al. (2012). The study presented a more resolved phylogenetic tree than previous studies through the use of data from a large number of genes. They included analyses of 82 plastid genes from 58 species (ignoring the problematic Rafflesiaceae), using partitions identified a posteriori by applying a Bayesian mixture model. Xi et al. identified 12 additional clades and three major, basal clades.

The older phylogenetic tree shown below is from Wurdack and Davis (2009). The DNA sequences of 13 genes, 42 families were placed into 16 groups, ranging in size from one to 10 families. The relationships among these 16 groups were poorly resolved. The statistical support for each branch is 100% bootstrap percentage and 100% posterior probability, except where labeled, with bootstrap percentage followed by posterior probability.

Malpighiales is monophyletic and in molecular phylogenetic studies, it receives strong statistical support. Since the APG II system was published in 2003, minor changes to the circumscription of the order have been made. The family Peridiscaceae has been expanded from two genera to three, and then to four, and transferred to Saxifragales.