Microlaena stipoides

Detailed description

Rhizomatous perennial with extravaginal branching, and much branched, multinoded stems of many cauline, often stiff hairy leaves, and often purpled spikelets on erectly branched narrow panicles. Branching extravaginal; rhizomes sometimes short; cataphylls chaffy. Leaf-sheath tight, short hairy or glabrous, overlapping node above, keel obscure. Ligule to 0.5 mm, finely erose, ciliate. Auricles 2, small, margin hairs (c. 3 mm) few. Collar short stiff hairy. Leaf-blade 5–25 cm × 2–5 mm wide, abaxially and adaxially abundantly stiff hairy sometimes more so abaxially, midrib prominent; margins with close-set, sharp teeth, retrorse below antrorse above, sometimes thickened, white, undulating. Culm to 85 cm, internodes many, glabrous, sometimes longitudinally grooved. Panicle 10–25 cm, narrow, slender, internodes short, branches erect to 5 cm, > internodes, rachis longitudinally grooved; branches and pedicels finely scabrid. Spikelets 25–35 mm, on slender finely scabrid pedicels; Ø lemmas often purple or purple-suffused. Glumes ± equal, 1-nerved, entire, often purple, margins ciliate, distant from Ø lemmas, < callus hairs; lower to 0.8 mm, upper to 1.5 mm. Callus 1–1.5–2 mm, clothed in hairs to 2 mm. Lower Ø lemma 12–20–30 mm, 5–7-nerved, scabrid, margin short (0.25 mm) hairy, awn > ½ lemma length. Upper Ø lemma 17–26–35 mm, prickle-toothed throughout or glabrous below and prickled above, 5–7-nerved, awn > ½ lemma length; callus hairs 0. ☿ lemma 5–7–9 mm, 5–7-nerved, shining, smooth except for teeth on upper ½ of keel, shortly awned (0.1–1.0 mm) from shortly lobed ciliate apex, margins hyaline; when cleistogamous often included by upper Ø lemma. Palea membranous, hyaline, produced into a mucro or becoming acute, apex ciliate; dimorphic, 4–6–8 mm in chasmogamous flowers, 2–3–4 mm in cleistogamous flowers. Lodicules 2, 1–2–2.7 mm in chasmogamous flowers occasionally hair-tipped, falling with caryopsis; 0 in cleistogamous flowers. Stamens 2–3–4; anthers 1.5–2.5–4.2 mm in chasmogamous flowers, (1)–2–3–4, 0.2–0.4–1.0 mm in cleistogamous flowers. Gynoecium: ovary 0.8–1.2 mm; stigma-styles 1.2–2.5–4.0 mm in chasmogamous flowers, 0.8–1.4–2.0 mm in cleistogamous flowers, stigma branches reaching ovary. Caryopsis laterally compressed, finely wrinkled, often falling free, 3.5–4.5–5.5 mm in chasmogamous flowers, 2–3.8–5.8 in cleistogamous flowers; embryo 0.6-1.0 mm. 2n= 48.