Tanglehead [Heteropogon contortus (L.) Roemer & Schultes][Bayer code: none][CDFA list: B] Photographs Map of Distribution

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SYNONYMSCommon speargrass, black speargrass, Andropogon contortus L., Heteropogon hirtus Pers.

GENERAL DESCRIPTION:Densely tufted tropical/subtropical perennial grass, to 0.8 m tall. Tanglehead is widely distributed native plant of uncertain origin in the tropical and subtropical regions of the world. Except for one population in the Sonoran Desert, tanglehead is considered a noxious introduction in California. The fruits can become entangled in the wool of sheep and puncture their skin, lowering the quality of the wool and meat. However, it is utilized as forage grass for cattle in Australia, Africa, and Southwestern U.S, and for its fiber in India.

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SEEDLINGS:No information available.

MATURE PLANT:Culms typically erect, sometimes abruptly bent near the base (geniculate), branched near the top. Blades 6-24 cm long, 0.4-0.8 cm wide, flat or folded, with a few long hairs near the ligule. Ligules membranous, ~ 1 mm long, truncate, fringed along the upper margin. Sheaths open, flattened.


SPIKELETS/FLORETS:Summer. Infloresences spike-like, terminal, 4-8 cm long, with paired spikelets on 1 side. Spikelet pairs with 1 sessile and 1 short-stalked. Lower 1-4 spikelet pairs similar, staminate. Upper spikelet pairs dissimilar. Stalked spikelets staminate, lack awns, ~ 10 mm long, with membranous, nearly glabrous glumes and lemmas. Sessile spikelets bisexual, ~ 7 mm long, nearly hidden by the stalked spikelets, with 2 florets (1 vestigial)/spikelet. Florets elliptic, hard, dark brown, with long reddish-brown hairs at the base and awned from the lemma tip. Awns 5-12 cm long, reddish-brown, covered with very short hairs, bent once or twice, wavy, typically tangled. After dispersal, floret bases are sharp and can injure the skin, eyes, and mouths of livestock.

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HABITAT:Open sites, rocky slopes, washes, especially depressions or sites where excess water is available. Plants require some summertime moisture.

DISTRIBUTION:Native in the Sonoron Desert (ne Imperial Co.). At publication time, introduced populations that have been eradicated occurred in the southern Southwestern region (sw San Diego Co.). To 800 m (2600 ft).

PROPAGATION/PHENOLOGY:Reproduces by seed. Germination is typically uneven. Optimal germination occurs between 30-35º C, but is inhibited when nighttime temperatures are cool (between 15-20º C). Most seed remains dormant for about 1 year after maturation. Seed longevity in the field is not well documented, but it is presumed that seed is viable for 1-2 years.

MANAGEMENT FAVORING/DISCOURAGING SURVIVAL:Burning appears to increase seedling recruitment.

SIMILAR SPECIES:Florets of tanglehead closely resemble those of the needlegrasses (Nassella, Acnatherum, and Heterostipa). However, unlike tanglehead, these species have infloresences in widely spreading to narrow panicles.

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