Trisetum Flavescens (L.) Beauv. (T. Pratense Pers., Avena Flavescens L.)

Abstract

A perennial grass producing small loose tufts, 20130 cm high. Culms are slender and unbranched, erect or less frequently spreading; 2-5-noded, sometimes hairy near the nodes, but otherwise smooth and shiny; nodes sometimes brown. Leaves mid-green, thin and softly hairy, on both surfaces, or lower hairless, with numerous slightly raised ribs. The lower sheaths are often densely hairy and rounded on the back. Ligule short, 0.5-2 mm long, membranous and fringed. Leaves up to 18 cm long and 1-4 mm wide and narrow to a fine point. Culm leaves usually 3, uppermost to 16cm long and 5.5mm wide. Panicles narrow, erect and dense to 17 cm long, golden green, greenish or purple at first, then gleaming golden yellow. Branches many, 27-55, in 8-11 whorls, often flexuous. Rhachis purple and rough. Pedicels 1-4mm long, the shorter ones at each node with spikelets almost to the base. Panicles with a wide range of spikelet numbers from 35-305. Spikelets linear-elliptical at first, then narrowly oblong-wedge-shaped; 4-7.5mm long, 2-3-(4) flowered, breaking up at maturity beneath each lemma. Glumes membranous and shiny, finely pointed and roughly keeled; unequal, upper glume elliptic, 3-nerved, 3.5-7mm long; lower glume narrowly lanceolate, 1-nerved, 2-4.5 mm long. Lemmas narrowly lanceolate, narrowing to 2-5 fine teeth at the tip, 36 mm long, 5-nerved, minutely hairy, purple apart from the membranous margins and tips. Awn arising from about halfway down the back of the lemma, 39 mm long, bent at the middle and twisted when dry. Awns with minute upward-pointing teeth. Paleas slightly shorter than the lemmas, 3-5.5 mm long, very thin and whitish, narrowing to a blunt point. The spikelet axis is shortly hairy, to 1 mm long. Lodicules 1 mm long and pointed. Grain narrow, 2-3 mm long and very firmly enclosed by the palea and lemma. Mean caryopsis oven-dry weight 0.2 mg. Root system a dense mass of gingery-brown fibrous roots, relatively unbranched in the upper parts, densely branched and with downy sheaths in the lower. Upper parts of roots to 1 mm diameter. Shortly creeping at the edges of the tufts with very short, hard rhizomes, 1.5 mm in diameter. Native. This is a complex species and the division into the three subspecies in Flora Europaea is tentative. Subspecies flavescens occurs throughout the range of the species. Subspecies splendens has been recorded from southern Italy, Sicily, Sardinia and the southern part of the Balkan peninsula, whilst subspecies purpurascens is recorded from the Carpathians and the Alps.