-(Distribution and anatomical characterization on the foliar colleters of Prestonia coalita (Vell.) Woodson (Apocynaceae)). A structural study on the foliar colleters of Prestonia coalita (Vell.) Woodson was conducted in order to establish their number and positions, to describe their structure, to determine in which stage of leaf development secretion starts and to comprove the presence of mucilage in its secretion. Each node presented 14-18 intrapetiolar colleters, whose differentiation occurs in the early stages of leaf development, and secretion occurs in leaf primordia with 5-8 mm length. Colleters are constituted by a long head that includes a central core of parenchymatous cells, surrounded by one layered palisade secretory epidermal cells, and a short stalk devoid of any epidermal secretory cells. Multicellular hairs and vascular tissue were observed only in intermediary colleters, which correspond with modified stipules. These structures' identification as colleters is confirmed by the presence of mucilage in secretion. The stipular nature of most colleters is confirmed, while only central colleters are originated from leaf axil.RESUMO -(Distribuição e caracterização anatômica dos coléteres foliares de Prestonia coalita (Vell.) Woodson (Apocynaceae)). Um estudo estrutural dos coléteres foliares de Prestonia coalita (Vell.) Woodson foi realizado com a finalidade de definir o número e a posição ocupada pelos coléteres, caracterizar a sua estrutura, determinar o estádio de desenvolvimento da folha em que eles se encontrem em fase secretora e comprovar a presença de mucilagem na secreção por eles produzida. Em cada nó, 14-18 coléteres intrapeciolares são observados; sua diferenciação ocorre nos estádios iniciais do desenvolvimento foliar e a atividade secretora em primórdios com ca. 5-8 mm de comprimento. Os coléteres são constituídos por uma longa cabeça, formada por um núcleo central de células parenquimáticas rodeado por epiderme uniestratificada secretora em paliçada, e um curto pedúnculo, no qual as células epidérmicas não secretoras apresentam formato cúbico a retangular. Tricomas multicelulares tectores e tecido vascular estão presentes apenas nos coléteres intercalares, que correspondem às estípulas modificadas. A identificacão destas estruturas como coléteres é comprovada devido à presença de mucilagem na secreção. A natureza estipular da maioria dos coléteres é confirmada, enquanto apenas os centrais são originados na região axilar da folha.
-(Leaf anatomy as subsidy to the taxonomy of Forsteronia G.Mey. species (Apocynaceae) in cerrados of São Paulo). The foliar anatomy of four cerrado species of Forsteronia was investigated in order to determine characters that could help to identify individuals collected in vegetative stage. Specimens of F. pubescens A.DC., F. thyrsoidea (Vell.) Müll.Arg., F. australis Müll.Arg., and F. glabrescens Müll.Arg. were collected in Moji-Guaçu and Itirapina cities (São Paulo state, Brazil).Results support the use of foliar features to achieve determination of individuals in vegetative state. Forsteronia australis differs from F. glabrescens in two macromorphological and four anatomical characters: 1. petiole outline in transverse sections; 2. occurrence of phloem strand above the petiole's midvein; 3. occurrence of secretory hypoderm in the petiole; 4. occurrence of trichomes in the domatia; 5. occurrence of secretory idioblasts and the aspect of their secretion; 6. axilar colleter type. F. pubescens is distinguished from F. thyrsoidea by eight characters: 1. petiole outline in transverse sections; 2. occurrence of phloem strands above the petiole midrib; 3. midvein shape; 4. position of secretory idioblasts in the petiole; 5. mesophyll type; 6. occurrence of crystal idioblasts; 7. occurrence of secretory idioblasts around main vascular bundle; 8. occurrence of axilar branched colleters. This is the first work describing domatia anatomy and sessile and branched colleters in vegetative organs of species of Apocynaceae. The characters described herein have taxonomic significance and are useful to identify Forsteronia species, thus contributing to a better delimitation of similar species found in cerrado vegetation of São Paulo.
Anemopaegma is a monophyletic lineage included in the tribe Bignonieae. The genus is taxonomically problematic, especially in the Anemopaegma arvense species complex, a group whose taxa have been delimited on the basis of leaf external morphology. Here we study the leaf anatomy of all three species and nine varieties currently included in this species complex (A. acutifolium DC., A. arvense (Vell.) Stellf. ex de Souza and A. glaucum Mart. ex DC.) in search for additional characters that may help circumscribe taxa within this group. For comparison, this study also investigated the leaf anatomy of two species that are morphologically similar to representatives of the species complex but currently placed outside it (A. album Mart. ex DC. and A. scabriusculum Mart. ex DC.). All taxa were analyzed using standard anatomical procedures and light microscopy. In addition, leaves of A. acutifolium and Anemopaegma album were analyzed with scanning electron microscopy (SEM). Overall, stomata position, composition of the vascular system of the petiole, midrib, lateral veins and margin constitution represented the most important anatomical features for the recognition of the species and varieties. The study also demonstrated that A. scabriusculum presents leaf anatomical traits that differ from those encountered in species of the Anemopaegma arvense complex, corroborating earlier anatomical and molecular phylogenetic results and indicating that A. scabriusculum is indeed best placed outside the A. arvense species complex. Leaf anatomical data also support the synonymization of some varieties of A. mirandum with A. arvense, as well as varieties of A. glaucum into this species.
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