Anatomia foliar como subsídio para a taxonomia de espécies de Forsteronia G. Mey. (Apocynaceae) dos cerrados paulistas

Abstract

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.) Mull.Arg., F. australis Mull.Arg., and F. glabrescens Mull.Arg. were collected in Moji-Guacu and Itirapina cities (Sao 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 Sao Paulo.