In Microlicieae taxonomical delimitation of Lavoisiera, Microlicia and Trembleya is problematic. This study aims to fill this gap by identifying leaf characters that are useful for taxonomy of these genera. Species of Rhynchanthera were also included in this study for comparison, since it is an early‐diverging genus of the tribe. Diagnostic characters of Lavoisiera include sessile leaves with spongy parenchyma composed of isodiametric cells, and acute margins with supporting tissue. Trembleya is distinguished by petiolate, microphyllous, and hypostomatic leaves. The presence of depressions on the leaf surface and a homogeneous mesophyll is observed only in species of Microlicia. The leaf characters observed in Rhynchanthera, together with the available phylogenetic studies, were important to indicate evolutionary tendencies in the leaf structure within Microlicieae. Thus, our results indicate a tendency for reduction in leaf size within the tribe, in relation to both the petiole and the lamina. This reduction, which is more pronounced in Microlicia, results in a greater anatomical heterogeneity, due to variations in the organization of both vascular and fundamental tissues.

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Two new species of Microlicia from campos rupestres of Minas Gerais are described, illustrated and compared with their relatives. Microlicia crassa sp. nov. is similar to M. formosa, and M. maculata sp. nov. is similar to M. isophylla and M. tetrasticha. The trichomes covering both surfaces of the leaves of the two new species and their relative, M. isophylla may be characterized as sessile glands under a stereomicroscope, but anatomical studies revealed the presence of a short stalk. Microlicia crassa and M. maculata are assessed as 'Endangered', according to the IUCN categories and criteria.In campos rupestres in the surroundings of Diamantina municipality, in Minas Gerais state, Brazil, at least 36 species of Microlicia D. Don are known to occur, of which six are taxonomic novelties (Romero 2013). Recognition of these novelties has been made with caution, because the morphological characteristics used to define species are generally very slight, hindering delimitation from closely related species. In Melastomataceae, leaf anatomical characters, such as the morphology and type of trichomes and stomata, and the presence or absence of emergences and position of the palisade parenchyma have provided diagnostic characters for recognizing certain species of Leandra Raddi, Miconia Ruiz & Pav., Acisanthera P. Browne, Tibouchina Aubl. and Microlicia D. Don (Reis et al. 2005). Thus, we believe that leaf anatomical data may also provide support for the characterization of new species of Microlicia.As a result of ongoing studies on the genus Microlicia in campos rupestres of the Cadeia do Espinhaço, in Minas Gerais state, we here describe two new species, including anatomical data for both, as well as for M. isophylla, a closely related species. Material and methodsThis study was based on literature and on the analysis of Microlicia specimens from the herbaria at BHCB, HUFU, K, MBM, NY, P, RB, SPF, UB, UEC and US (acronyms according to Thiers 2014), and on field observations in Biribiri State Park, Diamantina, Minas Gerais, Brazil. For the anatomical study, leaves were fixed in 50% FAA (Johansen 1940) and then preserved in 70% ethyl alcohol. Leaf samples of Microlicia isophylla DC. were removed from specimens deposited in the HUFU herbarium (A. P. M. Santos et al. 414), and were hydrated in 5% NaOH (Anderson 1963) for 12 h. Five mature leaves from different nodes of an individual of each of both new species were collected. Young leaves were also studied to confirm the presence and type of trichome and/or emergence, because these structures may be damaged in mature leaves of some Microlicia species. The samples, which were previously dehydrated in an ethanol series (70, 90 and 100%), were embedded in historesin. Transverse and longitudinal sections were prepared using a rotary microtome with tungsten blades, at the median third of the expanded adult leaf lamina, subsequently stained with toluidine blue (O'Brien et al. 1964) and mounted on permanent histological slides. Anatomical images were obtained with a Zeiss photomicr...

Leaf ontogenesis is determinant for the establishment and regulation of its structural and functional properties, in addition to being an excellent tool for assignment to different groups of angiosperms. Even though the importance of leaf morphology and anatomy for taxonomic use is well known, few studies have addressed the processes of leaf ontogeny in Melastomataceae. Herein, we sought to define the ontogenetic steps of leaf of Trembleya phlogiformis, highlighting the indumentum, to understand the main functional traits. Shoot apex, young and fully expanded leaves were processed by usual light microscopy procedures. At the first node, leaf primordia are densely covered with trichomes and emergences. The adaxial layer of ground meristem gives rise to the palisade parenchyma, the procambium originates from median layers of ground meristem and the spongy parenchyma develops from abaxial layers of ground meristem. The differentiation of isobilateral mesophyll on leaves of T. phlogiformis, a common feature in Microlicieae, comes from ground meristem stratification. However, T. phlogiformis stands out by showing in the leaf mature spongy parenchyma cells with irregular shapes. The leaf ontogeny reveals distinct mechanisms of cell differentiation and may be important for the establishment of functional adaptive traits.

Abstract—Vriesea is one of the genera of Bromeliaceae with the highest morphological diversity, including species of difficult recognition, many of them forming complexes, such as the Vriesea oligantha alliance. Morphological and anatomical comparative studies of vegetative and reproductive organs proved to be useful to solve such species complexes, besides indicating adaptive radiation. We analyzed comparatively the anatomy of roots, leaves, peduncles, and peduncle bracts of different populations found in rocky fields of Minas Gerais and Bahia, Brazil, with a taxonomic goal. In all the individuals studied the roots are composed of a velamen, a heterogeneous cortex, and a polyarch vascular cylinder, features that are common in the family. The leaves are covered by peltate trichomes and exhibit a hypodermis on both sides of the blade and a chlorenchyma composed of arm cells forming air lacunae between the collateral vascular bundles. The presence of subepidermal fiber strands in the leaves differentiates the populations of Minas Gerais from those of Bahia. The peduncle has an atactostele with compactly arranged cells in the cortex and pith. The peduncle bracts exhibit a greater number of peltate trichomes on the abaxial surface and secretory channels occur in the mesophyll. A cluster analysis (UPGMA) based on leaf morphology and tank channel diameter generated a dendrogram with four main clusters, which correspond to V. lancifolia, V. oligantha, and V. pseudoligantha, plus another taxon. Intraspecific variations in the color and margin shape of leaves and peduncle bracts are interpreted as adaptive responses to environmental factors, mainly luminosity.

Rocky outcrops represent the diversity center of vascular desiccation tolerant (DT) plants. Vegetation in this environment is exposed to an extended dry season and extreme conditions due to rocky soils and high sun exposure. In this study, we demonstrated that Pitcairnia burchellii, a bromeliad from rocky outcrops, tolerates intense desiccation for about 90 days due to strategies as accumulation of compatible osmolytes and antioxidant substances together with leaf morphological changes. In dehydrated plants, an increase in antioxidant activity was observed and the vacuolization of parenchyma cells was accompanied by proline accumulation in leaves and rhizomes. Precursors related to phenylpropanoid pathway increased significantly during plant dehydration. Accordingly, increases in anthocyanin and phenolic contents as well as lignin deposition were observed in leaves of dehydrated plants. Cell divisions and a decrease in stored starch were observed in the rhizomes indicating starch mobilization. Anatomical analyses revealed the presence of a more developed water-storage tissue in dehydrated leaves. During desiccation, leaves curl upwards and the adaxial V deep water-storage tissue is supported by two larger lateral vascular bundles. Cell wall folding and an increased proportion of arabinose-containing polymers was observed in leaves under dehydration, suggesting increasing of cell wall flexibility during desiccation. Such biochemical and morphological changes are consistent with the ability of P. burchellii to tolerate intense desiccation and behave as a resurrection species.

We here establish the Hohenbergia capitata complex composed of three species endemic to the Atlantic Forest, in the State of Bahia, Northeastern Brazil. When compared with other Hohenbergia species endemic to the Atlantic Forest, the complex is recognized by the small size of the plants (shorter than 1 m tall when flowering), lanceolate leaf blades, inflorescence with main axis short and congested branches, concentrated on the apical portion of the inflorescence (creating a capitulate shape), primary branches short pedunculate (short stipes), basal primary bracts sub-orbicular, large flowers (over 3 cm long) with spatulate petals with a cuspidate apex. Within this complex, we describe H. nidularioides sp. nov., a critically endangered species from the southern coastal region of Bahia, only known from a small fragment of Restinga forest in Una municipality. This species is very similar to H. capitata but differs by the nidular aspect of the inflorescence, which is only short-pedunculate and more or less hidden inside the rosette. In addition to the taxonomic treatment, we provide illustrations, the geographic distribution, taxonomic comments, and anatomical comparison of the species in the H. capitata complex.

Delimitation of genera and species in Bromeliaceae is often problematic, for example in the Neoregelia bahiana complex which is distributed throughout the rocky fields of the Espinhaço Range, Brazil. Considering that the anatomical characterisation of different organs is potentially important for taxonomic and ecological interpretation of this complex, we analysed roots, stems (stolon), leaves, inflorescence axes (peduncle) and pedicels in individuals from different populations. In all the studied individuals, the roots are composed of velamen, a heterogeneous cortex, and a polyarch vascular cylinder with sclerenchymatous pith. The stolon features a parenchymatous cortex and collateral vascular bundles randomly distributed in the vascular cylinder. This organ may increase in diameter by the formation of new vascular bundles and a multi‐layered cork. The leaf blade has epidermal cells with U‐shaped thickened walls and peltate scales occur on the adaxial surface. The mesophyll consists of mechanical and water‐storage hypodermis and a heterogeneous chlorenchyma. The inflorescence axis and the pedicel have a parenchymatous cortex and vascular bundles randomly distributed in an aerenchyma. Some variable leaf characters, such as presence of air lacunae in the mesophyll, are related to the size of the individuals and were interpreted as phenotypic variations related mainly to sunlight incidence. In contrast, leaf characters such as lamina shape, distribution of the peltate scales, and number of cell layers forming the water‐storage hypodermis distinguish the populations of the Serra do Cabral and one population of the Diamantina (Minas Gerais) from the remaining studied populations, suggesting the existence of more than one taxon.