Hymenachne amplexicaulis 'Olive' *

Hymenachne amplexicaulis* (Rudge) Nees. Mex. Pl. 2: 51, 67 (1886).

Classification. (GPWG 2001) : Subfamily Panicoideae. Paniceae.

Basionym and/or Replacement Name:  Panicum amplexicaule Rudge, Pl. Guian. 1: 21, pl. 27 (1805).

Type of Basionym or Protologue Information: T: Rudge s.n., Guianas (?). IT: mis. Nees ab Esenb., Brazil, British Giuana (LE-TRIN-0576.01). riliq. specimina Martinicensia Sieber s.no 266. T: Martin s.n., French Guiana? (BM). T: British Guiana.

Key references (books and floras): [2002] D.Sharp & B.K.Simon, AusGrass, Grasses of Australia, [2008] S.W.L.Jacobs, R.D.B.Walley & D.J.B.Wheeler, Grasses of New South Wales (281).

Illustrations: [2008] S.W.L.Jacobs, R.D.B.Whalley & D.J.B.Wheeler, Grasses of New South Wales, 4th edn (281).

Habit. Perennial. Culms decumbent, stature robust to moderate, 200–350 cm tall, spongy. Mid-culm internodes solid. Mid-culm nodes glabrous. Leaf-sheaths glabrous on surface. Ligule an eciliate membrane, 1–2.5 mm long. Leaf-blades lanceolate, 15–33 cm long, 12–28 mm wide. Leaf-blade surface glabrous.

Inflorescence. Inflorescence solid, a panicle. Panicle linear, 10–40 cm long, 1–2 cm wide.

Spikelets. Spikelets pedicelled. Fertile spikelets 2-flowered, the lower floret barren (rarely male), the upper fertile, comprising 1 basal sterile florets, comprising 1 fertile floret(s), without rachilla extension, lanceolate, dorsally compressed, 3–4 mm long.

Glumes. Glumes dissimilar, thinner than fertile lemma. Lower glume ovate, hyaline, without keels, 3 -nerved. Upper glume lanceolate, 2.8–3.9 mm long, membranous, without keels, 5 -nerved. Upper glume apex awned. Florets. Basal sterile florets 1, barren, without significant palea. Lemma of lower sterile floret 100 % of length of spikelet, membranous, 5 -nerved.

Fertile lemma 2.5–3.5 mm long, without keel, 3 -nerved. Palea 2 -nerved, without keels. Anthers 3.

Continental Distribution: Australasia, North America, and South America.

Australian Distribution: Northern Territory, Queensland.

Northern Territory: Darwin & Gulf. Queensland: Cook, Leichhardt, North Kennedy, South Kennedy.

Notes. Introduced relatively recently as a "ponded pasture" species in Qld and N.T., but spreading fairly rapidly as an aquatic weed.

AVH 2011


Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith