Epidermal structure in the ligules of four species of the genus Poa L. (Poaceae)

The structure of the abaxial epidermis of the ligules of mid- and upper-culm leaves of the grasses Poa annua, P. nemoralis, P. pratensis and P. trivialis as seen by light microscopy is described. Amongst the structural elements found were long cells, short cells and unicellular prickle hairs over the surface, with unicellular hairs and papillate cells on the free edges of the ligules. Ligules of upper-culm leaves of some plants of P. trivialis L. contained vascular tissue with associated green (chlorenchyma) regions and stomata-like structures. The value of ligule characters in grass identification and classification is briefly discussed.