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Aspidosperma (Apocynaceae) is composed of trees and shrubs; the genus includes 70 species, 42 of which occur in Brazil. The midwestern region has the second highest diversity, with 30 species, after the northern region, and Mato Grosso do Sul state has 15 species. This study provides macroscopic and microscopic wood features for ten species from A. section Aspidosperma and A. section Pungentia (Apocynaceae) from Mato Grosso do Sul state, Brazil. These characteristics can aid in the identification of Aspidosperma species because the nine species of these two sections have many morphological similarities; moreover, the wood of these species is economically important for timber production. Through macroscopic and microscopic analysis procedures, the characteristics of the wood and the organoleptic properties allowed recognition and distinction of the studied taxa. The characters of diagnostic value for recognition of the sections are vessel frequency and arrangement, and ray width. Individually, each species had a set of characteristics that allowed its identification: wood color; vessel arrangement; vessel length; ray visibility, ray composition and width; presence of crystals, starch grains and lipids in axial and/or ray parenchyma cells. The results may support conscientious exploitation by industries by facilitating the correct identification of the species, and will also help in the detection of illegal timber logging. [ABSTRACT FROM AUTHOR]

Petalostelma is a taxonomically neglected genus of Apocynaceae with only seven species of climbing plants and voluble subshrubs with the smallest flowers of Metastelmatinae (c. 6 mm in diam.), mainly characterized by rotate corolla and fleshy gynostegial corona, with or without an annular corolline corona. During the revision of the genus, we recognized three new species of Petalostelma, two of which had specimens misidentified as P. sarcostemma, a species originally known only from Argentina. Here, we describe and illustrate these new species – P. andinum, P. auriculatum and P. longipedunculatum – and compare them with the other species of Petalostelma that also have flowers without corolline corona. The three new species occur in the Andean dry forests of Bolivia, but P. andinum also occurs in Argentina and P. longipedunculatum in the Brazilian Cerrado. Additionally, the occurrence of P. sarcostemma is confirmed for Bolivia and reported for the first time in Brazil here. [ABSTRACT FROM AUTHOR]

Rhabdadenia (Apocynaceae) includes three species, Rhabdadenia biflora, Rhabdadenia madida, and Rhabdadenia ragonesei. These species are morphologically similar and phenotypically plastic in their vegetative organs and flower color, and despite recent taxonomic revisions of the genus, species identification and delimitation remains a challenge. In this study, we investigate leaf and stem anatomy of all Rhabdadenia species to establish unequivocal taxonomically diagnostic characters. We encountered distinct anatomical differences in (1) leaf characters, notably the stomata distribution, which is restricted to the main veins in R. ragonesei and spread across the entire lamina for the other two species; (2) the presence and form of papillae, which are dome type in R. biflora, cone type in R. madida, yet absent in R. ragonesei; (3) the number of layers of palisade parenchyma, which are two in R. biflora and one in both R. ragonesei and R. madida; (4) the shape of the vascular bundle in the midrib, which is concave-convex in R. ragonesei and convex-concave in R. madida and R. biflora; (5) the leaf blade margins, which are sharply arched downward in R. madida, slightly flexed in R. ragonesei, and straight in R. biflora. A dichotomous identification key is presented. This work enables unequivocal, rapid identification of Rhabdadenia species using leaf anatomy, even in the absence of reproductive parts. Our work also determined that Rhabdadenia is distinct within Apocynaceae by the presence of articulated anastomosed ramified laticifers, as opposed to the unarticulated laticifers that are typical of the family. [ABSTRACT FROM AUTHOR]

The article presents descriptions and illustrations of Barjonia furlanii (Asclepiadoideae, Apocynaceae), a new species from Serra da Canastra National Park, in the state of Minas Gerais, Brazil. It discusses the species' similarities to B. laxa, especially in its frondose thyrsoid inflorescence, compound corona, and linear leaves. It also cites the species' distinctions from B. laxa including much shorter pedicels, erect leaves, and partial inflorescences that alternate with 2-4 flowers.

Aspidosperma flaviflorum, is described as a new species from the submountain semideciduous forest in the municipality of Porto Murtinho in the state of Mato Grosso do Sul, Brazil. This new taxon is described and compared with the most morphologically similar species, A. quirandy and A. tomentosum. In its wood anatomy, A. flaviflorum is unique within the genus by the very scanty axial parenchyma and the lack of a line of axial parenchyma delimiting the growth rings. [ABSTRACT FROM AUTHOR]

• The venation pattern is of high diagnostic value in recognizing the species studied. • Both species exhibit adaptive xeromorphic characteristics in the Chaco Biome. • Both in Chaco, one more mesophytic, the other more xerophytic. Aspidosperma is one of the most representative genera in Apocynaceae in Brazil, composed of trees or small trees popularly known as perobas. The genus is distributed throughout tropical America, from Mexico to Argentina, with the exception of Chile. It comprises 80 species, 42 of which occur in Brazil, which is the center of diversity for the genus. Aspidosperma triternatum and Aspidosperma quebracho-blanco , name the Aspidosperma sect. Pungentia , section is easily distinguished from the others, even in the vegetative state, by grouping species that have leaves with pungent apexes, unique in the genus. However, A. triternatum and A. quebracho-blanco are difficult to distinguish due to the morphological similarities they present, such as the pungent apex of their whorled leaves and the yellowish white color of their flowers. Therefore, our objective was to develop a study to obtain leaf morphological using the usual methods of microscopy. The most important diagnostic characters useful for delimiting the species were: the number of pairs of secondary veins; the patterns of distance between these and the median and distal region, as well as the reticulation of these veins; the branching of the tertiary veins; the impression of the quaternary veins as well as their development and the shape of the areola; shape of epidermal cells; cuticular ornamentation pattern; types and distribution of trichomes; distribution of stomata; organization and number of cell layers in mesophyll. We have shown from the performed study that the species have remarkable morphological and anatomical differences which made possible a better circumscription of the group. [ABSTRACT FROM AUTHOR]