Micromorfologia e anatomia da lâmina foliar do complexo Saccharum (Poaceae - Andropogoneae)

Abstract

In a broad sense, the genus has about 40 species and is related to other genera due to morphological similarities and phylogenetic proximity between them, composing the Saccharum complex. The genera that compound the group are: Erianthus, Lasiorhachis, Miscanthidium, Miscanthus, Narenga, Saccharum, Sclerostachya and Tripidium. Sugarcane (Saccharum officinarum), of great importance for the world economy, is included in the genus Saccharum. This study aimed to investigate the micromorphology and comparative leaf anatomy of Saccharum and related genera, in order to contribute with data to the taxonomy of the group. Anatomical analyses of the median leaf region were performed under an optical microscope for 41 species from all genera within the Saccharum complex. The samples were obtained from herbarium material and prepared according to standard methods of plant anatomy. Micromorphological analysis was conducted using a scanning electron microscope (SEM). Histological slides were photographed to record the results using a light microscope with an attached digital camera. Features such as the presence of microtrichomes, prickles, and short cells were observed in all analyzed species. However, the genera exhibited distinct patterns in some characteristics, such as the arrangement of buliform cells, number of layers and nature of the bundle sheath, and the presence of colorless cells just below the epidermis. Additionally, anatomical differences were observed within Erianthus between species from South America and those from North America. For the Old World species, there was considerable variation in anatomical characteristics among the species. Lasiorhachis and Tripidium, despite being phylogenetically distant from the other genera in the Saccharum complex, share many anatomical characteristics with them. This study demonstrates that micromorphology and leaf anatomy are of great importance in assisting the delimitation of taxa within the Saccharum complex.