The classification of the legume family proposed here addresses the long‐known non‐monophyly of the traditionally recognised subfamily Caesalpinioideae, by recognising six robustly supported monophyletic subfamilies. This new classification uses as its framework the most comprehensive phylogenetic analyses of legumes to date, based on plastid matK gene sequences, and including near‐complete sampling of genera (698 of the currently recognised 765 genera) and ca. 20% (3696) of known species. The matK gene region has been the most widely sequenced across the legumes, and in most legume lineages, this gene region is sufficiently variable to yield well‐supported clades. This analysis resolves the same major clades as in other phylogenies of whole plastid and nuclear gene sets (with much sparser taxon sampling). Our analysis improves upon previous studies that have used large phylogenies of the Leguminosae for addressing evolutionary questions, because it maximises generic sampling and provides a phylogenetic tree that is based on a fully curated set of sequences that are vouchered and taxonomically validated. The phylogenetic trees obtained and the underlying data are available to browse and download, facilitating subsequent analyses that require evolutionary trees. Here we propose a new community‐endorsed classification of the family that reflects the phylogenetic structure that is consistently resolved and recognises six subfamilies in Leguminosae: a recircumscribed Caesalpinioideae DC., Cercidoideae Legume Phylogeny Working Group (stat. nov.), Detarioideae Burmeist., Dialioideae Legume Phylogeny Working Group (stat. nov.), Duparquetioideae Legume Phylogeny Working Group (stat. nov.), and Papilionoideae DC. The traditionally recognised subfamily Mimosoideae is a distinct clade nested within the recircumscribed Caesalpinioideae and is referred to informally as the mimosoid clade pending a forthcoming formal tribal and/or clade‐based classification of the new Caesalpinioideae. We provide a key for subfamily identification, descriptions with diagnostic charactertistics for the subfamilies, figures illustrating their floral and fruit diversity, and lists of genera by subfamily. This new classification of Leguminosae represents a consensus view of the international legume systematics community; it invokes both compromise and practicality of use.

The Eriocaulaceae are easily recognized because of the small unisexual flowers in long-pedunculate heads and spiraperturate pollen grains. Their monophyly has never been disputed but internal relationships within the family have not been broadly explored and genera are typically distinguished by few floral characters. Here, we present the first comprehensive phylogenetic study of Eriocaulaceae based on individual and combined molecular datasets, including the plastid psbA-trnH and trnL-F and the nuclear ITS. Results are largely congruent among DNA regions and support the internal dichotomy between the two subfamilies: Eriocauloideae and Paepalanthoideae. Eriocaulon and Leiothrix are strongly supported as monophyletic, whereas Paepalanthus, Blastocaulon, and Syngonanthus are not monophyletic. The phylogenetic nature of Actinocephalus is not resolved and Lachnocaulon, Mesanthemum, Philodice, Rondonanthus, and Tonina (monospecific) are represented in our analyses by a single species each. Based on our results, we suggest two principal generic realignments in the family. The first is the division of Syngonanthus in two genera: Syngonanthus s.str., including Philodice (conserving the former name against the latter), and Comanthera, which is being reinstated to include two sections segregated from Syngonanthus: S. sect. Eulepis and S. sect. Thysanocephalus. The second realignment suggested is the amalgamation of Actinocephalus, Blastocaulon, Lachnocaulon, and Tonina into Paepalanthus s.l. Three 'stat. nov.' within Paepalanthus are published (P. ser. Leptocephali, P. ser. Rosulati, and P. ser. Dimeri).

Chamaecrista Moench is a genus of caesalpinioid legumes with about 330 species mostly from the New World. The phylogeny of the genus was studied using sequence data from nuclear ITS and plastid trnL­F DNA spacers, representing all six sections of Chamaecrista. Separate and combined analyses recovered the same major clades with high bootstrap and posterior probabilities support, except for the subclades of representatives of sections Caliciopsis, Chamaecrista, and Xerocalyx. The monophyly of Chamaecrista was highly supported in all analyses. Sections Apoucouita and Xerocalyx were supported as monophyletic, sect. Absus was paraphyletic and subsect. Baseophyllum was resolved more closely related to species of sections Chamaecrista, Caliciopsis, and Xerocalyx than to subsect. Absus. The monotypic section Grimaldia was embedded within subsect. Absus. Section Chamaecrista was paraphyletic with respect to sections Caliciopsis and Xerocalyx. Our analyses suggest that the diversification patterns in Chamaecrista occurred through an initial shift from rainforest trees to a more diverse clade of savannah shrubs. Within the latter group, two main subclades were recovered: (1) a planaltine and high­mountain clade characterized by absence of extrafloral nectaries and the appearance of sticky glandular hairs; and (2) a mostly herbaceous clade with axillary fascicled inflorescences and reduced chromosome numbers. This last group is more diverse in open grassland areas and includes many colonizers of waste ground.