The first anatomical and histochemical study of tough lovegrass (Eragrostis plana Nees, Poaceae)

Eragrostis plana Nees (Poaceae), known commonly as tough lovegrass, is the most abundant invasive plant found in the rangelands of Southern Brazil. This study is the first to document the anatomical and histochemical features of the leaves and roots of this grass. Five leaf blades and five roots were collected, fixed in formaldehyde, glacial acetic acid, ethanol 70° (FAA 70), sectioned, stained, and photographed under a light microscope. Anatomical analysis of the leaves was supplemented with observations under a scanning electron microscope. Manual cuts were made into fresh material, which was subjected to specific reagents to determine the lipid, phenol, tannin, lignin, alkaloid, and starch presence. The analyses revealed that the leaves are amphistomatic with paracytic stomata, and the epidermis has lignified cells, a Kranz structure, collateral vascular bundles of two sizes, tectors, unicellular and crystalline trichomes. The roots are polyarc with air gaps on the cortical parenchyma, U-thickened endodermal cell walls and a parenchymatic pith with starch storage cells. Leaves and roots contain lipids, phenols, lignins, and alkaloids; starch is only present in the roots. Anatomical and histochemical traits of tough lovegrass suggest that the plant has adapted to survive under biotic and abiotic stress, which enhances its performance in relation to native plants.   Key words: Anatomy, histochemistry, invasive.