Plants annual; tufted. Culms 20-90 cm, sometimes decumbent, often with many branches arising from the base. Sheaths strongly compressed-keeled; ligules 0.6-1.8 mm; blades 4-27 cm long, 1.5-5(7.5) mm wide, adaxial surfaces scabrous or sparsely pilose. Panicles 1.5-8(10) cm; fascicles 8.3-11.9 mm long, 3.5-6 mm wide, somewhat globose, medium- to short-pubescent; bristles 45-75; outer bristles numerous, shorter and thinner than the inner bristles, imbricate, mostly terete, reflexed; inner bristles 3.5-7 mm long, 0.5-0.9(1.4) mm wide at the base, irregularly placed, fused for 1/2 their length or more, forming a distinct cupule, the distal portions diverging at irregular intervals from the cupule, often grooved along the margins, purple-tinged. Spikelets 2-3(4) per fascicle, (4)5.8-7.8 mm. Lower glumes 0.8-3 mm; upper glumes 4-6 mm, 3-5-veined; lower florets often staminate; lower lemmas 4-6.5 mm, 3-7-veined; anthers 1.5-2 mm; upper lemmas 4-7(7.6) mm; anthers 0.7-1 mm, seemingly not well-developed at anthesis. Caryopses 2-3.8 mm long, 1.5-2.6 mm wide, ovoid. 2n = 34 (38).
Cenchrus longispinus grows in sandy woods, fields, and waste ground in southern Canada and the contiguous United States. Its range extends southwards to Venezuela. It is often confused with C. spinifex and C. tribuloides; see discussion under those species.
Annual herb, tufted 20 cm - 1 m tall
Leaves: alternate, two-ranked. Sheaths strongly compressed and keeled, hairy towards the apex. Ligules 0.5 - 2 mm long. Blades 4 - 27 cm long, 1.5 - 7 cm wide, linear, flat, parallel-veined, rough or sparsely soft-hairy on top.
Inflorescence: a terminal, spike-like, branched arrangement of "burs" (termed fascicles), 1.5 - 10 cm long.
Fruit: a caryopsis, indehiscent, enclosed within the persistent lemma and palea, 2 - 4 mm long, 1.5 - 2.5 mm wide, egg-shaped.
Culm: spreading or ascending, many-branched from base, 20 cm - 1 m long, round in cross-section, solid, knee-like, internodes hollow.
Spikelets: two to four per fascicle, stalkless, 5 - 8 mm long, oblong lance-shaped.
Florets: two per spikelet. Lower floret often male. Upper floret bisexual. Anthers three, 1.5 - 2 mm long (lower) or 0.5 - 1 mm long (upper). Stigmas red.
Fascicles: (the "burs" of the inflorescence) composed of many stiff, partially fused spines, stalkless, 8 - 12 mm long, 3.5 - 6 mm wide, somewhat spherical, hairy, enclosing spikelets.
Glumes:: Lower glumes 0.5 - 3 mm long, egg-shaped with a more or less pointed apex, one-veined. Upper glumes 4 - 6 mm long, egg-shaped, three- to five-veined.
Lemmas:: Lower lemmas 4 - 6.5 mm long, equaling their paleas, egg-shaped, three- to seven-veined. Upper lemmas 4 - 7 mm long, nearly equaling their paleas, egg-shaped with a tapering apex, obscurely veined.
Paleas:: Lower paleas purplish or tawny. Upper paleas egg-shaped with a tapering apex, obscurely veined.
Similar species: No information at this time.
Flowering: July to mid-September
Habitat and ecology: Common in sandy soil.
Occurence in the Chicago region: native
Notes: The "burs" of this species often adhere to shoe laces and clothing.
Etymology: Cenchrus comes from cenchros, a modified Greek name for Setaria italica (millet). Longispinus means long-spined.
Author: The Morton Arboretum
Common Name: mat sandbur
Duration: Annual
Nativity: Native
Lifeform: Graminoid
General: Loosely tufted, often prostrate and mat forming annuals; stems 10-40 cm long, branched at the base, sometimes rooting at the nodes, geniculate, glabrous, leafy.
Vegetative: Sheaths compressed-keeled, the collar sometimes puberulent, otherwise glabrous, margins scarious, sometimes extended as membranous auricles, sometimes diverging from the stem; ligule a dense fringe of hairs, 0.5-1.5 mm long, marginal hairs sometimes up to
Inflorescence: Panicle 3-6 cm long, bearing 4-12 burs, rachis geniculate, flattened and angled, scabrous to glabrous; bur urceolate to globose, the body 3-5 mm broad when pressed, enclosing 2 sessile spikelets and covered with 45-55 spines, upper spines large, flat, spreading to ascending.
Ecology: Found in open ground and waste places, a weedy plant in disturbed areas, often in sandy soil.
Notes: This plant has terrifically gnarly seeds. Distinguished from C. spinifex by having longer spikelets, more brisles, narrower inner bristles, and terete outer bristles.
Ethnobotany: Unknown
Etymology: Cenchrus is thought to be from Greek kenchros, millet, and longispinus means long spines.
Synonyms: Cenchrus carolinianus
Editor: SBuckley, 2010
Spreading or ascending annual 2-8 dm, usually branched; sheaths villous-ciliate distally; blades 6-18 cm נ3-7 mm; burs hairy, 8-12 נ3.5-6 mm (spines excluded), with numerous (mostly 45-75) retrorsely barbed, slender spines 3.5-7 mm, the lower spines relatively short and pointed downward; spikelets 2-3(4) per bur, 6-8 mm, exserted at the tip, visible down to the middle through the lateral cleft in the bur; 2n=34. A weed in sandy soil or disturbed habitats; Me. to Fla., w. to N.D., Oreg., Calif. and Tex.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
©The New York Botanical Garden. All rights reserved. Used by permission.
