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The description of starch is an important aspect on several investigative studies: from the analysis of food adulteration and in the authenticity of common flours, to the development of hypotheses about the cultivation and domestication of plants in hominid populations as old as the Paleolithic. In Brazil, there’s a few data available on the microscopic description of starch, so this work aimed to analyze morphologically the starch granules in popular sources of starch obtained in specialized stores, markets, and fairs of three municipalities of the state of Rio de Janeiro and develop an identification key of them. The samples was analyzed by optical and scanning electron microscopy (SEM). Falsifications were found in three arrowroot flours of different brands and origins. Consequently, it reflects the contribution of starch granules microscopy analysis to indicate the importance of legitimate cultivation of arrowroot and other traditional crops of the Brazilian flora. Spherical, polyhedral and ovoid granules are frequent in the species studied, with round-triangular and campanulate granules specific for identifying false-arrowroot and cassava, respectively. The descriptions and misunderstands found in literature were updated. For example the distinction of lenticular granules from ellipsoids in wheat, barley, and rye. Finally, a starches identification key is proposed, together with an update of important data for its morphological description.

The genus Philodendron Schott comprises the following three currently accepted subgenenera: P. subg. Philodendron, P. subg. Pteromischum and P. subg. Meconostigma; however, these lack a well-defined classification. In the present study, we examined anatomically samples of adventitious roots in species of the group, so as to establish aspects relevant for taxonomic purposes. The anatomical analyses emphasised the characteristics of the steles in cross-sections of the root samples from regions near the apex to the most mature zones. A species of a closely related genus Adelonema, namely A. crinipes, was included in the study to clarify the results. Our results indicated notable differences in the species of the subgenus Meconostigma, mainly in terms of the presence (and variations) of a lobed stele, whereas the cylindrical stele stood out among the common characteristics in P. subg. Philodendron, P. subg. Pteromischum and the related species A. crinipes. Moreover, the characteristics shared by P. subg. Philodendron and P. subg. Pteromischum corroborated the phylogenetic hypothesis that these two taxa were more closely related to one another than to P. subg. Meconostigma.