Heteropogon contortus (L.) P.Beauv.
ex Roem. & Schult.
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Common name
Spear Grass
Bunch Speargrass
Black Speargrass
Derivation
Heteropogon Pers., Syn. Pl. 2: 533 (1807); from the Greek heteros
(different) and pogon (beard), alluding to the difference between the
awnless male and awned female spikelets.
contortus- Awns hygroscopic and so twisted when dry.
Published in
Syst. Veg. 2: 836 (1817).
Habit
Perennial, tufted. Young shoots intravaginal. Culms erect, 30100 cm tall,
1.53 mm diam. Mid-culm internodes solid. Mid-culm nodes black, glabrous.
Lateral branches branched or fastigiate. Leaves cauline. Ligule a fringe of
hairs, 1 mm long. Collar glabrous or pilose. Leaf-blades flat or conduplicate,
330 cm long, 28 mm wide. Leaf-blade surface ribbed. Leaf-blade apex
abruptly acute.
Inflorescence
Peduncle antrorsely scabrous above. Rames single,
erect, unilateral, 36 cm long. Rhachis fragile at the nodes, glabrous on
margins. Rame internodes linear. Rame internode tip oblique.
Spikelets
Spikelets appressed, in pairs, one sessile and fertile and the other (companion)
spikelet pedicelled. Pedicels oblong, semiterete, 20% of length of fertile
spikelet. Basal sterile spikelets well-developed, 634 in number. Basal
sterile spikelets larger than fertile. Basal sterile spikelet glumes smooth
on margins. Basal sterile spikelet lower glume muticous. Companion spikelets
developed, containing empty lemmas or male, asymmetrical, lanceolate, dorsally
compressed, 515 mm long, longer than fertile, separately deciduous. Companion
spikelet callus linear, 23 mm long. Companion spikelet glumes chartaceous,
eglandular, winged on margins, distinctly nerved, smooth or tuberculate, glabrous
or pubescent or pilose or villous, acute, muticous. Companion spikelet lemmas
2, enclosed by glumes. Fertile spikelets 2-flowered, comprising 1 fertile floret,
lower floret sterile, upper fertile, without rhachilla extension, linear, terete,
510 mm long, falling entire, deciduous with accessory branch structures.
Spikelet callus linear, 23 mm long, bearded, base pungent, attached obliquely.
Spikelet callus hairs red, 11.5 mm long, 20% of length of spikelet.
Glumes
Glumes dissimilar, with lower wider than upper, firmer than fertile lemma. Lower
glume linear, 100% of length of spikelet, hyaline or coriaceous, dark brown,
59-nerved. Lower glume surface puberulous or pubescent or pilose. Lower
glume apex obtuse. Upper glume linear, 4 mm long, coriaceous, 3-nerved. Upper
glume apex muticous.
Florets
Basal sterile floret 1, without significant palea. Lemma of lower sterile floret
linear, 100% of length of spikelet, hyaline, 2-nerved, erose. Fertile lemma
linear, 35 mm long, membranous, 1-nerved. Lemma apex entire, 1-awned.
Median (principal) awn apical, geniculate, 5080 mm long overall, with
a twisted column. Column hirtellous. Palea absent or minute. Anthers 3, 2.53
mm long. Stigmas 2.
Continental Distribution:
Europe, Africa, Temperate Asia, Tropical Asia, Australasia, Pacific, North America,
South America.
Australian Distribution:
Western Australia, Northern Territory, Queensland, New South Wales.
Western Australia: Gardner, Fitzgerald, Hall, Dampier, Canning, Fortescue. Northern Territory: Darwin & Gulf, Victoria River, Barkly Tableland, Central Australia North, Central Australia South. Queensland: Cook, Burke, North Kennedy, South Kennedy, Port Curtis, Leichhardt, Burnett, Wide Bay, Darling Downs, Moreton, Gregory North, Mitchell, Warrego, Maranoa. New South Wales: North Coast, Northern Tablelands, North-Western Slopes, Central-Western Slopes, North-Western Plains.
Classification. (GPWG
2001):
Panicoideae: Andropogoneae
Notes
A pantropic species. Very variable morphologically, particularly
the hairiness of the pedicelled spikelet. Readily eaten by stock although the
seed, with its pungent callus, presents a problem at maturity. Flowers all year.
Habit (photo)
© B. Carter