Morphometric analysis of the Saccharum complex (Poaceae, Andropogoneae)

Abstract

Saccharum s.l. comprises 35–40 species, including sugarcane (S. officinarum), and is distributed in the tropics and subtropics. The term “Saccharum complex” refers to four related genera: Saccharum, Erianthus s.l. (including E. sect. Ripidium, or Tripidium), Narenga, and Sclerostachya. Miscanthus and Miscanthidium are also closely related to this group. The delimitation of these genera is contentious and largely unresolved, with most species recognized under Saccharum. This study aimed to assess the morphological variation of the Saccharum complex, especially Saccharum s.s. and Erianthus s.l., and contribute to clarifying their generic circumscriptions. To accomplish this purpose, 31 exomorphological characters (17 qualitative and 14 quantitative) were analyzed using cluster (UPGMA) and discriminant analyses. The existence of significant differences among groups was analyzed by a one-way MANOVA. The morphological evidence clearly indicated three groups: (1) Saccharum s.s. from the Old World, (2) Tripidium + some species of Saccharum s.l. sometimes recognized as Narenga, Miscanthus, or Miscanthidium (all taxa from the Old World), and (3) Erianthus s.s. from the New World. The results support that the native species from the New World (Erianthus s.s.) are morphologically different from the species of Saccharum s.s. often cultivated, suggesting that Erianthus should be accepted as a genus distinct from Saccharum. For the species of Tripidium, we provide the morphological traits that distinguish them from Saccharum s.s. and Erianthus s.s. and revalidate the recent differential recognition postulated by molecular works.