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)
Ecuador (Galápagos Islands) Santa Cruz Group	Santa Cruz 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
El Salvador El Salvador	El Salvador (Republic of)	native	Swallen, Jason R./McClure, F. A. (1955) (p. 78)
Guatemala Guatemala	Guatemala (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)
Nicaragua Nicaragua	Nicaragua (Republic of)	native	Swallen, Jason R./McClure, F. A. (1955) (p. 78)
Perú Perú	Perú (Republic of)	native	Swallen, Jason R./McClure, F. A. (1955) (p. 78)

Additional information:
Additional online information about Cenchrus pilosus is available from the Hawaiian Ecosystems at Risk project (HEAR).

Information about Cenchrus pilosus as a weed (worldwide references) may be available from the Global Compendium of Weeds (GCW).

Taxonomic information about Cenchrus pilosus may be available from the Germplasm Resources Information Network (GRIN).

References:

Charles Darwin Foundation. 2008. Database inventory of introduced plant species in the rural and urban zones of Galapagos. Charles Darwin Foundation, Galapagos, Ecuador.

Charles Darwin Research Station. 2005. CDRS Herbarium records.

Hitchcock, A. S. 1927. The grasses of Ecuador, Peru, and Bolivia. Contr. U. S. Natl. Herb. 24(8).

Swallen, Jason R./McClure, F. A. 1955. Flora of Guatemala. Grasses of Guatemala. Fieldiana: Botany. Vol. 24, Part II. Chicago Natural History Museum. 390 pp.