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The seed micromorphology was studied in eight species of Xyris(Xyridaceae) with taxonomic purposes. The results show that the presence of longitudinal endotegmic ridges in the seed coat is a pattern for the genus and that the shape of these ridges differentiates among the species. The following characteristics are also useful to identify the species: shape and size of the seed, number of cell rows between the ridges, and the striation pattern of the seed coat. Based on these characteristics, a standard terminology is proposed to describe the seed coat in species of the genus. An identification key for the studied species is also provided.

Paepalanthussect. Diphyomenecomprises 18 species with a convoluted taxonomic history. Aiming to correlate anatomical structures with the systematics of this group and its relatives, we studied the anatomy of scapes, reproductive axis bracts, and leaves of 20 Paepalanthusspecies. Bracts and leaves show differences in epidermal cell thickening; mesophyll width; vascular bundle arrangement; presence or absence of a hypodermis; types of cells in the vascular bundle sheath extensions; margin shape and composition; and presence or absence of aquiferous parenchyma. Scapes differ in contour, rib number, and pith size. Some diagnostic characters found are presence of aquiferous parenchyma and absence of vascular bundle sheath extensions in leaves of P. urbanianus; vascular bundles decreasing in size towards the margin of leaves and bracts, and scapes with a triangular contour in P. flaccidus; scapes with nine ribs in P. acanthophyllusand ten in P. macer. All anatomical features are summarized in tables. These results aid in the identification and characterization of the species of P. sect. Diphyomene.They also support the current section circumscription, reinforcing the relevance of the anatomical characters in order to define natural groups.

Bulbophyllumsection Micranthaecomprises 12 species of rupicolous or epiphytic orchids occurring in forests or in open rocky fields in Cerrado/Atlantic Forest ecotones throughout South America. We examined the leaf anatomy of 14 species and compared them with molecular data (nrITS) in phylogenetic analyses. The leaves of Bulbophyllumsection Micranthaeare characterised by uniseriate epidermis, with periclinal external cell wall thicker than the internal, presence of epicuticular wax, stomata present only on the abaxial surface with suprastomatic chambers, and collateral vascular bundles associated with sclerenchyma fibres. Some of these characters are shared with other rupicolous Orchidaceae species, demonstrating adaptive convergence in xeromorphic habitats. We found some anatomical characteristics with phylogenetic value. Bulbophyllumsection Micranthaecan be separated into two lineages: those with needle-like leaves, or flat leaves. The analyses show that anatomical characters as well as molecular data may contribute to the development of phylogenetic hypotheses.

The morphological and anatomical leaf and scape differentiation ofLeiothrix crassifolia is analysed and classified into seven types (I, II, III, IV, V, VI, VII). The species has a relatively wide distribution in the campo rupestre of Minas Gerais in Brazil. Variation in the isolated populations on different mountain ranges is complex, does not follow a clear geographical pattern, and defies taxonomic classification.L. nubigena andL. obtusifolia are included inL. crassifolia.