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Copyright of Willdenowia is the property of Botanischer Garten & Botanisches Museum Berlin-Dahlem, Freie Universitat Berlin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

After synonymization of Araujia and Morrenia (Asclepiadoideae, Apocynaceae), there are 12 Araujia spp., with the Chaco region, including Argentina, Bolivia, Brazil and Paraguay, as their centre of diversity. If recognized independently, neither genus is monophyletic, but consensus on this circumscription remains unclear. Therefore, to improve our understanding of the taxonomy of Araujia and Morrenia and their relationships, this research aimed to (1) find new characters based on leaf morphology and anatomy and (2) investigate how these characters are distributed in the most recent phylogenetic tree for the group. Leaves of four Araujia spp. and six Morrenia spp. were obtained from field trips and herbarium material and analysed using scanning electron and light microscopy, herbarium specimens and images. Although leaf morphoanatomical features vary across these genera, results support inclusion of Morrenia in Araujia. This outcome agrees with previous phylogenetic studies in which Araujia and Morrenia emerged as clades with high bootstrap support (100%). Our results also indicate that leaf morphoanatomical features support fewer inclusive clades in the phylogeny of Araujia-Morrenia, a finding that should be useful in future taxonomic studies. Finally, we present a previously unpublished species key. [ABSTRACT FROM AUTHOR]

Copyright of Rodriguésia is the property of Revista Rodriguesia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Neotropical Biology / Revista de Biologia Neotropical is the property of Journal of Neotropical Biology / Revista de Biologia Neotropical and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)