Pacific Island Ecosystems at Risk (PIER)

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Cenchrus pilosus
Kunth, Poaceae
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Present on Pacific Islands?  yes

Primarily a threat at high elevations?  no

Habit:  grass

Description:  "Annual; caespitose. Culms 30-60 cm long. Leaf-sheaths keeled; smooth, or antrorsely scabrous. Ligule a fringe of hairs; 0.5-1.6 mm long. Leaf-blades 6-30 cm long; 4-11 mm wide. Leaf-blade surface glabrous; hairless except near base. Inflorescence a panicle. Panicle spiciform; linear; dense (internodes 1-2.5mm); 2-13 cm long; 0.8-2.7 cm wide. Primary panicle branches accrescent to a central axis; with sessile scars on axis. Panicle axis angular; scabrous; bearing deciduous spikelet clusters. Spikelets subtended by an involucre. Fertile spikelets sessile; 2-3 in the cluster. Involucre composed of bristles; connate into a cup below; with 2-4 mm connate; globose; 5-8 mm long; base obconical. Involucral bristles deciduous with the fertile spikelets; numerous; with an outer whorl of thinner bristles; inner bristles longer than outer; 3-6 mm long; flattened; flexible; smooth; pubescent; attenuate.  Spikelets comprising 1 basal sterile florets; 1 fertile florets; without rhachilla extension. Spikelets ovate; dorsally compressed; acuminate; 6-7 mm long; falling entire; deciduous with accessory branch structures. Glumes shorter than spikelet; thinner than fertile lemma. Lower glume ovate; 1-4 mm long; 0.2-0.5 length of spikelet; membranous; without keels; 1-veined. Lower glume lateral veins absent. Lower glume apex acute. Upper glume ovate; 3-6 mm long; 0.5-0.8 length of spikelet; membranous; without keels; 3-5-veined. Upper glume apex acute. Basal sterile florets barren; with palea. Lemma of lower sterile floret ovate; 4-7 mm long; 0.6-1 length of spikelet; membranous; 3-7-veined; acute. Fertile lemma ovate; 5-7.5 mm long; coriaceous; much thinner on margins; without keel; 3 -veined. Lemma margins flat. Lemma apex obtuse. Palea coriaceous. Anthers 0.9-1.8 mm long. Caryopsis with adherent pericarp.  (Grassbase).

"Annual; culms 10 cm to nearly 1 meter high, erect or decumbent at the base, simple or sparingly branching; blades rather thin,, flat, scabrous, or sometimes papillose-pilose, 10-40 cm long, 6-12 mm wide; spikes 2-14 cm long, dense, erect, usually long-exserted on relatively stout peduncles; body of bur about 5 mm thick, densely pilose, the bristles antrorsely scabrous, much exceeding the bur; spikelets usually 3. Spikelets short-pedicellate, dorsally compressed, the rachilla between the glumes elongate, the bearded base of the first glume adnate to it, forming a long slender callus; glumes narrow or broad, extending into long awns; sterile lemma short-awned or awn-tipped only; fruit subindurate, the lemma acuminate, pointed or awned, the margins thin, flat, not enclosing the summit of the palea" (Swallen, 1955; p. 78).

"A spreading, rather stout annual similar to Cenchrus echinatus, but usually decumbent and rooting at the lower nodes; burs larger than those of C. echinatus, the bristles antrorsely scabrous, the inner twice as long as the body of the bur" (Hitchcock, 1927; p. 78).

Habitat/ecology:  "Sand bars and rocky slopes at low altitudes" (Swallen, 1955; p. 78). "Open ground and cultivated soil" (Hitchcock, 1927; p. 78).

Propagation:  Seed (attaching burs).

Native range:  Mexico, El Salvador, Nicaragua, Colombia and Venezuela to Peru (Swallen, 1955; p. 78). Mexico to Ecuador (Hitchcock, 1927; p. 78).

Presence:

Pacific
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Ecuador (Galápagos Islands)
San Cristóbal Group
San Cristóbal Island introduced
invasive
Charles Darwin Foundation (2008)
Pacific Rim
Country/Terr./St. &
Island group
Location Cited status &
Cited as invasive &
Cited as cultivated &
Cited as aboriginal introduction?
Reference &
Comments
Central America
Central America (Pacific rim)
El Salvador (Republic of) native
Swallen, Jason R./McClure, F. A. (1955) (p. 78)
Central America
Central America (Pacific rim)
Guatemala (Republic of) native
Swallen, Jason R./McClure, F. A. (1955) (p. 78)
Central America
Central America (Pacific rim)
Nicaragua (Republic of) native
Swallen, Jason R./McClure, F. A. (1955) (p. 78)
Mexico
Mexico
Mexico (United Mexican States) native
Swallen, Jason R./McClure, F. A. (1955) (p. 78)
South America (Pacific rim)
South America (Pacific rim)
Perú (Republic of) native
Swallen, Jason R./McClure, F. A. (1955) (p. 78)


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This page was created on 18 JUN 2004 and was last updated on 13 MAR 2012.