Stipa tirsa is a species of perennial grass native to Europe and temperate Asia. Culms are 40âÂÂ100 cm long; leaf blades are filiform, involute, and 1âÂÂ2 mm wide.
S. tirsa is a perennial, tuft-forming grass with culms 40âÂÂ100 cm tall. Leaf-sheaths are glabrous, ligules short (0.2âÂÂ0.5 mm), and blades filiform, involute, 1âÂÂ2 mm wide, puberulous and hairy beneath, with attenuate tips. The inflorescence is a contracted, linear panicle subtended at the base by a leaf. Spikelets are solitary, pedicelled, and 50âÂÂ65 mm long, each with a single fertile floret and disarticulating at maturity. Glumes are lance-shaped (lanceolate), pointed (acuminate), membranous, and longer than the florets (50âÂÂ65 mm). The fertile lemma is elliptic, 18âÂÂ20 mm long, pubescent in lines, convolute around the inner bract (palea), and terminates in a single awn. The awn is bent twice (bigeniculate), 350âÂÂ500 mm long, with a twisted column and feathery (plumose) limb. The inner bract equals the lemma in length, 2-veined. Flowers have three small scales (lodicules), three smooth-tipped anthers, and two stigmas; the ovary is glabrous. The fruit is a grain (caryopsis) with adherent outer layer (pericarp) and a linear narrow scar (hilum).
According to Plants of the World Online, Stipa tirsa is native to parts of Europe and Asia, occurring from the Iberian Peninsula eastwards to Siberia.