contortus (L.) Roemer & Schultes][Bayer code: none][CDFA list: B] Photographs Map
SYNONYMSCommon speargrass, black speargrass, Andropogon
contortus L., Heteropogon hirtus Pers.
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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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
and UNDERGROUND STRUCTURES:Fibrous.
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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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).
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.
FAVORING/DISCOURAGING SURVIVAL:Burning appears to increase seedling recruitment.
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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