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.

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Tullasnella spp. have been found forming mycorhizal associations with plants of all Orchidaceae subfamilies, and they are one of the main symbionts in partially micoheterotrophic plants (Taylor et al. 2002). Little is known about mycorhizal fungi of Neotropical Orchidaceae, especially in Laeliinae that occur in distinct environments such as “Restingas”, Seasonal Forests and “Campos Rupestres” (Cruz et al. 2003, Britto et al. 1993, França et al. 1997, Withner 2000).