Ischaemum aristatum L.

no known common names


Info

Subfamily: Panicoideae
Genus etymology: Ischaemum = "to stop bleeding" [Greek] referencign supposed medical uses
Species etymology: aristatum = "possessing a bristle" [Latin] refering to the awned lemmas
Photosynthetic type: C4 (warm season)
Nativity: naturalized - accidental
First recorded in Hawaiʻi: 1994

Map

 Distribution of Ischaemum aristatum in Hawaiʻi.

Inflorescence

Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence
Ischaemum aristatum Inflorescence

Plant

Ischaemum aristatum Plant
Ischaemum aristatum Plant
Ischaemum aristatum Plant

Spikelets

Ischaemum aristatum Spikelets
Ischaemum aristatum Spikelets

Node

Ischaemum aristatum Node

Description

Perennial. Culms loosely tufted, erect or geniculately ascending, 40–80 cm tall, simple or branching, nodes glabrous. Leaf sheaths glabrous or pilose; leaf blades linear lanceolate, 5–25 × 0.4–1 cm, glabrous or thinly pilose, margins smooth becoming scabrid toward apex, base attenuate or contracted, apex acuminate; ligule 2–3 mm. Racemes terminal, paired, appressed back to back, 4–7 cm; rachis internodes clavate, triquetrous, scabrid or ciliate along outer angle, inner angles glabrous or shortly ciliate. Sessile spikelet oblanceolate to obovate, 5.5–8 × 2–2.3 mm; lower glume leathery with rounded flanks below middle, herbaceous, broader and 2-keeled above, 5–7-veined, keels narrowly to broadly winged, wing margin scabrid; upper lemma awnless or shortly awned; awn well developed or imperfect, up to 1.2 cm. Pedicelled spikelet dorsally compressed, resembling sessile, asymmetrical, 2-keeled, keels winged, one wing incurled. Fl. and fr. Jul–Oct. 2n = 56, 72.
(Description source: Wu, Z.Y., Raven, P.H. & Hong, D.Y. (eds.). 2006. Flora of China. Volume 22. Poaceae. Missouri Botanical Garden Press, St. Louis. 733 pp. )

Habit Perennial; caespitose; clumped loosely. Rhizomes short. Culms decumbent, or prostrate; 30-80 cm long; 1.2-2 mm diam. Culm-internodes terete, or channelled; 4-12(-25) cm long; smooth; distally glabrous. Culm-nodes glabrous, or pubescent. Lateral branches lacking, or sparse; arising from lower culm. Leaves cauline. Leaf-sheaths outer margin glabrous, or hairy. Ligule an eciliate membrane; 3-4 mm long; scarious; brown; truncate. Leaf-blades linear, or lanceolate; 5-30 cm long; 4-10 mm wide. Leaf-blade surface glabrous, or pilose; sparsely hairy. Leaf-blade margins smooth, or scabrous. Leaf-blade apex acuminate. Inflorescences Inflorescence composed of racemes. Racemes 2; paired; appressed back to back; 4-7 cm long; 5-8 mm wide. Rhachis fragile at the nodes; angular; scaberulous on margins; glabrous on margins, or pubescent on margins. Rhachis internodes columnar; 3-4 mm long; flat and forming a U or V shape with the pedicel in rear view. Rhachis internode tip transverse; cupuliform. Spikelets in pairs. Fertile spikelets sessile; 1 in the cluster. Companion sterile spikelets pedicelled; 1 in the cluster. Pedicels columnar; glabrous, or puberulous. Sterile Companion sterile spikelets well-developed; male; ovate; 4-6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes; muticous, or 1-awned; with 0-3 mm long awn. Spikelets Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate, or rhomboid; dorsally compressed; 5-8 mm long; 2-2.3 mm wide; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous; base truncate; inserted. Companion sterile spikelets well-developed; male; ovate; 4-6 mm long; shorter than fertile; separately deciduous. Companion sterile spikelet glumes chartaceous; keeled; muticous. Companion sterile spikelet lemmas 2; enclosed by glumes; muticous, or 1-awned; with 0-3 mm long awn. Fertile Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets obovate, or rhomboid; dorsally compressed; 5-8 mm long; 2-2.3 mm wide; falling entire; deciduous with accessory branch structures. Spikelet callus glabrous; base truncate; inserted. Glume Glumes dissimilar; exceeding apex of florets; firmer than fertile lemma. Lower glume elliptic; 1 length of spikelet; coriaceous; much thinner above; 2-keeled; keeled above; keeled laterally; winged on keel; winged broadly; winged above; 5 -veined. Lower glume primary vein scabrous. Lower glume lateral veins obscure; with cross-veins; intercarinal veins distinct; intercarinal veins 3 in number. Lower glume surface convex. Lower glume apex dentate; 2 -fid. Upper glume lanceolate; 1 length of spikelet; coriaceous; 1-keeled; keeled above; 5 -veined. Upper glume primary vein scabrous. Upper glume apex acute. Florets Basal sterile florets male; with palea. Lemma of lower sterile floret ovate; hyaline; acute. Fertile lemma elliptic; hyaline; without keel. Lemma apex lobed; 2 -fid; awned; 1 -awned. Principal lemma awn from a sinus; straight, or geniculate; 1-10 mm long overall; clearly exserted from spikelet, or not or scarcely exserted from spikelet; without a column, or with twisted column. Palea 1 length of lemma. Flowers Anthers 3; 2.5 mm long. Distribution Africa: western Indian ocean. Asia-temperate: China and eastern Asia. Asia-tropical: India, Indo-China, Malesia, and Papuasia. Pacific: southwestern, northwestern, and north-central.
(Description source: Clayton, W.D., Vorontsova, M.S., Harman, K.T. and Williamson, H. (2006 onwards). GrassBase - The Online World Grass Flora. Available at https://powo.science.kew.org )