Leaf anatomy for delimiting Atlantic Forest species of Psidium (Myrtaceae)

Abstract

Leaf anatomical features are widely used to better understand angiosperm taxonomy. However, such information is scarce for the family Myrtaceae. Aiming to fill this knowledge gap, we studied anatomical and micromorphological leaf characters of ten species of Psidium: P. cattleyanum, P. cauliflorum, P. corynanthum, P. guajava, P. guineense, P. macahense, P. myrtoides, P. oligospermum, P. ovale and P. sartorianum. Uniseriate epidermis, paracytic stomata, secretory cavities, and adaxial hypodermis are common among the studied species and are typical characteristics of Myrtaceae. The presence of three or more layers of palisade parenchyma and the absence of sclerenchyma are diagnostic characters of P. guajava. The abaxial epidermis of Psidium cattleyanum and P. macahense possess curved walls. Psidium corynanthum and P. macahense are the only species with sinuous anticlinal walls on both sides of the epidermis, with all other species having straight or curved walls. Open bicollateral vascular bundles are present in all the studied species except P. guineense. With the exception of P. cauliflorum, all the studied species possess druses. The absence of collenchyma in the adaxial face is exclusive to P. ovale. The leaf anatomy of P. macahense, P. corynanthum, P. oligospermum and P. ovale are described for the first time here.

Key words
anatomical features; angiosperm; quantitative characters; UPGMA; taxonomy