The Collaborative International Dictionary of English v.0.48:

Fiorin \Fi"o*rin\, n. [Cf. Ir. fiothran a sort of grass.] (Bot.)
   A species of creeping bent grass (Agrostis alba); -- called
   also fiorin grass.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Agrostis alba
    n 1: slender European grass of shady places; grown also in
         northeastern America and temperate Asia [syn: wood
         meadowgrass, Poa nemoralis, Agrostis alba]