Morpho-anatomical analysis of Aspidosperma olivaceum and A. polyneuron, Apocynaceae

The family Apocynaceae includes many medicinal species, such as Aspidosperma olivaceum Müll. Arg. and A. polyneuron Müll. Arg. The first, popularly known as "peroba-branca", is a source of indole alkaloids that are recognized for their antitumor activity. The second, known as "peroba-rosa", is used by some people for treating malaria. To contribute to the knowledge about Brazilian medicinal plants and potential vegetal drugs, a morpho-anatomical analysis of the leaves and stems of these tree species was carried out. The botanical material was fixed, sectioned and stained using standard techniques. Histochemical tests were performed and the material was also analyzed using a scanning electron microscope. Aspidosperma olivaceum and A. polyneuron are morphologically similar, both presenting alternate, simple, elliptic-lanceolate leaves. The leaves are hypostomatic with anomocytic stomata and have non-glandular trichomes. In the stem, there are peripheral phellogen, lignified fibers and some stone cells in the cortex and pith, as well as numerous gelatinous fibers near the phloem. Prismatic calcium oxalate crystals and laticifers are present in the leaves and stems. Unlike A. olivaceum, A. polyneuron also has cyclocytic stomata, predominantly unicellular non-glandular trichomes and a biconvex midrib with a sharper curve on the adaxial side. In addition, A. olivaceum differs because it has some idioblasts with phenolic content.