Heteropogon contortus (PROTA)

From PlantUse English
Jump to: navigation, search
Prota logo orange.gif
Plant Resources of Tropical Africa
Introduction
List of species


General importance Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svgGood article star.svg
Geographic coverage Africa Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svg
Geographic coverage World Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svg
Essential oil / exudate Fairytale bookmark gold.svgGood article star.svgGood article star.svgGood article star.svgGood article star.svg
Medicinal Fairytale bookmark gold.svgGood article star.svgGood article star.svgGood article star.svgGood article star.svg
Forage / feed Fairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svgGood article star.svgGood article star.svg
Auxiliary plant Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svgGood article star.svg
Fibre Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svgGood article star.svg
Climate change Fairytale bookmark gold.svgFairytale bookmark gold.svgFairytale bookmark gold.svgGood article star.svgGood article star.svg


Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult.


Protologue: Syst. Veg., ed. 15 bis, 2: 836 (1817).
Family: Poaceae (Gramineae)
Chromosome number: 2n = 20, 36, 39, 40, 44, 50, 58, 60, 70, 80, 90. Tropical genotypes are predominantly tetraploid, while subtropical ones range from tetraploid to enneaploid.

Synonyms

  • Andropogon contortus L. (1753),
  • Heteropogon hirtus Pers. (1807),
  • Heteropogon hispidissimus A.Rich. (1851).

Vernacular names

  • Speargrass, black speargrass, bunch speargrass, tangle grass, tanglehead grass, tanglehead, assegai grass, pili grass (En).
  • Herbe polisson, herbe barbue, herbe à moutons (Fr).
  • Flechinha (Po).
  • Kichoma mguu, kichoma nguo, kishona nguo, kishona (Sw).

Origin and geographic distribution

Heteropogon contortus is native to the tropics and subtropics of Africa, southern Asia, northern Australia and parts of Oceania. It is widely naturalized in tropical and subtropical regions of the Americas, East Asia and Oceania. It is grown in Australia, India, South America and the United States. In tropical Africa it is commonly found from Cape Verde, Mauritania and Senegal eastwards to Eritrea and Somalia and southwards to Angola, Mozambique, South Africa, and in the Indian Ocean islands.

Uses

Heteropogon contortus is used as thatch for huts and is commonly woven into mats. The cellulose content of the grass is quite high and it has been examined for pulping for paper manufacture, but with poor results. Heteropogon contortus is a good forage and fodder grass when young, but very troublesome to man and animals and even injurious to the latter after flowering because of the sharp-pointed seeds which may penetrate the skin and the membranes of the mouth and intestines. Also, the awns entangle with the fur of animals, especially the fleece of sheep. A second limitation to animal production is the wide fluctuation of herbage growth and quality between wet and dry seasons. The grass is mainly used as part of the natural savanna pasture. Young herbage can be conserved as hay or silage. Heteropogon contortus could be planted for erosion control and revegetation of degraded habitats. Zulu people in South Africa use the plant in the treatment of burns, wounds and rheumatism. The plant also is diuretic. In Benin a decoction of the inflorescence is a component of a medicine drunk against irritability. In Zambia bees have been observed visiting the plant for pollen.

Production and international trade

Heteropogon contortus is only used locally.

Properties

Tests in India showed that Heteropogon contortus grass can yield about 48% unbleached pulp using a soda pulping process with a kappa number of 22.0–27.2 without enzyme and 20.6–26.0 with enzyme. Handmade test pulp sheets with adequate strength properties were obtained from soda pulp.

As forage, the grass is palatable in the early vegetative stages, but intake and digestibility decline rapidly as it matures. By the end of the growing season, it is only eaten if supplemented with urea and molasses. In unimproved pasture the dry-matter protein content ranges from 10% in very young green material from the early flush of the growing season to about 5% during much of the growing season and to as low as 1% in dry forage by the end of the dry season. These levels are lower than those in species such as Panicum maximum Jacq. and Chloris gayana Kunth. Crude protein levels are not raised greatly by application of fertilizer nitrogen. Experiences from India showed that the crude protein content of a Heteropogon community was about 5% when untreated, and 5.8% when fertilized with nitrogen. Phosphorus levels in the dry matter range from 0.09–0.15%, and calcium from 0.23–0.30%. In plants at early bloom with 34% dry matter and 6.6% crude protein, acid detergent fibre (ADF) was 22% and neutral detergent fibre (NDF) 52%. In mature plants corresponding values were dry matter 42%, crude protein 4.4%, ADF 32% and NDF 64%. Digestibility varies similarly from 60% down to 40%. The sharply pointed and barbed seeds are an additional drawback.

A study conducted on indigenous grasses in Botswana showed that the dry matter content of hay made of various grasses was highest in Heteropogon contortus (78.4% in June and 85.7% in the rainy season in December). However, its crude protein content was lowest, and decreased from 4.9% in June to 1.3% in December. The study confirmed that during the dry season, the dry matter and fibre content (neutral detergent fibre and acid detergent fibre) increased, while the crude protein content of the grass decreased. Digestibility also decreased during the dry season. The mineral content of the grass was lower than average except for calcium.

Description

Tufted perennial grass 0.5–1.5 m tall, rather variable in habit; stems erect to geniculate at the base, often branched above, particularly at flowering, flattened towards the base, glabrous, smooth; nodes smooth and glabrous. Leaves basal and on the culm, green or bluish; leaf sheath smooth, compressed, keeled, striate, sometimes with a few hairs near the ligule; ligule a short, membranous rim; blade linear, 3–30 cm × 2–8 mm, folded in the lower part, becoming flat, slightly rough to the touch with a few long hairs particularly towards the base, apex blunt, almost canoe-shaped. Inflorescence a simple raceme of pairs of spikelets arranged in 2 rows, 3–8 cm long (excluding the awns), the outermost ones pedicellate and overlapping and enclosing the innermost sessile spikelets; at the base of the raceme the spikelets are similar and unawned, male or sterile, at the top the spikelets are dissimilar, comprising sessile, bisexual, awned spikelets and pedicellate, male or sterile, unawned spikelets; sessile spikelet 2-flowered, 5–10 mm long, with a pungent and bearded callus 2–3 mm long, glumes as long as spikelet, lower glume 5-veined, upper glume 3-veined, lower lemma c. 1/2 the length of the spikelet, sterile, without a palea, upper lemma stipe-like at the base and passing into a twisted awn 5–10 cm long, stamens 3, stigmas 2, purple; pedicellate spikelet unawned, 5–15 mm long, glumes sometimes hairy and enclosing reduced lemmas, the base of the spikelet bearing a callus 2–3 mm long; spikelets at the base of the raceme resembling the pedicelled spikelets. Fruit a caryopsis (grain), cylindrical, 3.5–4.5 mm long, grooved, whitish.

Other botanical information

Heteropogon is a member of the tribe Andropogoneae. It comprises 6 species and occurs throughout the tropics, extending to warm temperate regions. Heteropogon contortus is extremely diverse in habit and hairiness of the spikelets, and is adapted to a wide range of rainfall regimes. The narrowly cylindrical racemes of overlapping green spikelets, with stout brown intertwining awns emerging from the upper part, are very characteristic of this species. Heteropogon contortus is apomictic, producing seed with vegetatively formed embryos, but sexual reproduction also occurs. This has led to a considerable amount of localized variation, resulting in the proliferation of local species and varieties in the early botanical literature. An annual form has been described from India, but this could be a short-lived perennial form growing in a difficult environment.

Heteropogon melanocarpus (Elliot) Benth. (‘sweet tanglehead’) is an annual grass up to 2 m tall, occurring from southern China westward through tropical and subtropical Asia and tropical Africa to the tropical and subtropical parts of America. Like Heteropogon contortus it is used for grazing when young.

Growth and development

Heteropogon contortus is a relatively short-lived perennial. Grazing pressure influences survival of individual tussocks. Under light grazing, individual plants can live for several years.

Heteropogon contortus exhibits a high degree of embryo and seed-coat dormancy in freshly ripened seed. This declines over the dry season to a high level of germination at the first rains of the next wet season. Subsequently, the germination rate falls off rapidly with little or no survival beyond one year. Seeds which are burrowed into the soil are in a favourable environment for germination. In a stand there can be over 5000 seeds per square meter. Flower initiation is obligatory to facultatively short day, the former being characteristic of the tropical forms, which flower late in the wet season, and the latter of the subtropical forms which flower early to mid season. The late flowering forms have higher leaf yields and are more responsive to increased soil fertility.

Heteropogon contortus is largely dormant during the cooler, drier months. Vegetative growth begins when both temperature and soil moisture levels are adequate. In an area in south-western Zimbabwe where Heteropogon contortus is the dominant component of natural grassland, it was found to be very sensitive to the availability of soil moisture. Growth was vigorous after significant rainfall, but slowed or ceased after 2–3 dry weeks. When rain returned, rapid growth of green leaves resumed as tillers continued growth. Peak shoot yield varied greatly from year to year, and was attained near the end of the growing season as soil moisture was depleted. Shoot yields then declined, primarily as a result of litter fall. Plants tend to be weakly rooted late in the dry season. Heteropogon contortus uses the C4 photosynthetic pathway.

Ecology

As a typical member of the Andropogoneae, Heteropogon contortus is a savanna grass growing in seasonally warm wet and cooler dry climates. It is most abundant in the understorey of various woodlands and open forests such as Combretum-Terminalia woodland. Themeda triandra Forssk. and species of Bothriochloa, Eragrostis, Aristida, Chloris and Chrysopogon are common associates of Heteropogon contortus. It often forms nearly pure stands. It appears not to be dominant in undisturbed climax vegetation, but may become so through habitat disturbance such as heavy grazing and burning, particularly in Australia, India and Africa.

Heteropogon contortus tolerates light shade and often dominates the understorey of Eucalyptus woodlands in tropical and subtropical Australia, but is much less shade tolerant than Panicum maximum Jacq. It is most abundant where annual rainfall averages 600–1000 mm, and where there are marked wet and dry seasons, but is also found well outside these limits, such as on parts of the Big Island of Hawaii with an average annual rainfall of only 210 mm. It does not tolerate long periods of flooding, but can tolerate a few days’ inundation on otherwise well-drained soils. It does not tolerate high salinity. Heteropogon contortus occurs over a wide range of average annual temperatures, from 28°C near sea-level in Sri Lanka to 11°C at an altitude of 3800 m in Peru and 15.5°C at 1300 m in South Africa. Heteropogon contortus is moderately frost tolerant, although plants are usually mature by the time of the first frosts.

Heteropogon contortus grows on a wide variety of soils, ranging from sandy loam to clay loam and soil type plays only a minor role in determining distribution. It can grow on infertile sands and strongly layered soils but also on very fertile clay loams. It is much less common on some heavy clay soils, soils with poor drainage, under conditions of extremely low fertility and in saline situations. Heteropogon contortus generally prefers sandy loams with pH 5.0–6.0.

Propagation and planting

Heteropogon contortus can be propagated by seed or vegetatively. Seed cleaning is difficult because the awn and callus are not easily removed without damaging the seed, while without the removal of the awn and callus, sowing is difficult. Since commercial seed is scarce, most small-scale establishment has been vegetative using splits of mature plants. Seed should be sown no deeper than about 1 cm, preferably into a fine, firm and clean seedbed, and rolled after sowing. The 1000-seed weight is 7 g with awns, and 2 g without awns. Because fresh seed shows dormancy, seed should be stored for 6–12 months before sowing. In nature, the twisting action of the hygroscopically active awns and the sharp, barbed tip of the seed play an important role in pushing the seed into the soil. Disturbances increase recruitment of the seedlings. The optimum temperature for germination is 30–35°C, while germination is inhibited by night temperatures of 15–20°C. Seedlings do not compete well against better adapted species in recently cultivated, N-rich soils.

Management

In its natural state in savanna, Heteropogon contortus has a relatively short period of growth and adequacy for livestock nutrition. This causes a large part of the annual biomass production to become unusable and to be left as dry standing material. Commonly this material is burnt during or at the end of the dry season. This procedure leads to increasing dominance of Heteropogon contortus in the vegetation, especially in conjunction with grazing. Burning is also commonly used to maintain Heteropogon contortus pastures. Crops can be shredded or burned on an annual basis or once every 2–3 years. However, burning during the dry season may reduce nutrient availability.

Under continuous heavy grazing, Heteropogon contortus declines, and can be reduced to a minor component of pastures, particularly on poor soils or where high stocking rates are sustained through supplementary feeding. It is most susceptible to grazing in the early part of the wet season. One recommendation for long-term maintenance of Heteropogon contortus pastures is that utilization rates should not exceed 30%.

Although it is adapted to low-nutrient soils, an up to 8-fold improvement of livestock production from natural Heteropogon contortus pastures can be achieved by introducing tropical legumes such as Stylosanthes spp., or Macroptilium atropurpureum (DC.) Urban in the subtropical zones. This improvement comes from both increased carrying capacity and rate of growth of the livestock. However, care must be taken, especially in the more strongly seasonal tropics, to avoid overgrazing as a result of the increased stocking rates. Moderate levels of fertilizer application benefit growth and rapid establishment, but high levels of fertilizer nitrogen can kill plants. In India, application of 20 kg N/ha raised dry matter production from 3340 kg/ha to 4330 kg/ha, while 40 kg N/ha raised it to 5560 kg/ha. If sown with a legume, application of phosphate fertilizer can benefit the legume component, and reflect in improved animal performance. For rotational grazing, a forage height of 10–25 cm should be utilized. It is recommended that 15 cm is maintained as a minimum stubble height under continuous grazing. Heteropogon contortus does not develop seed if it is consistently grazed, and populations will decrease if grazing is too heavy. In Queensland (Australia), the carrying capacity of native Heteropogon contortus pastures is one animal to 3.5–4 ha in the southern area and to 8–10 ha in the north of the region. Cattle lose weight in the winter and spring and take 4–5 years to reach market weight.

Diseases and pests

Several smut diseases of the inflorescence have been reported on Heteropogon contortus. A recent revision placed them all in the genus Sporisorium. Ergot (Claviceps spp.) may affect seed production, particularly under cool, moist conditions. Leaf rust caused by Puccinia versicolor or Uromyces clignyi is common on more mature leaves. Heteropogon contortus acts as a collateral host for downy mildew caused by Peronosclerospora sorghi on sorghum and maize. Rice shoot fly (Atherigona oryzae) has been recorded as a pest of Heteropogon contortus.

Harvesting

Heteropogon contortus can be harvested with brush or beater harvesters to get hay-bales containing viable seed, which can be used for rehabilitation purposes. Since the panicles have a tendency to tangle when mature, harvesting can also be done easily with a ‘pili comb’

Yield

In India dry matter yields up to 5560 kg/ha have been reported.

Genetic resources

While Heteropogon contortus is mainly used in natural stands, a few named selections are available, such as ‘Rocker’ from Arizona and ‘Kahoolawe’ from Hawaii. Heteropogon contortus is not threatened with genetic erosion as it occurs widely over the world. Its genetic diversity is also preserved in germplasm collections, e.g. at the Southern Regional PI Station, Griffin, Georgia of the USDA/ARS National Genetic Resources Program, and in Indonesia, Ethiopia and Zimbabwe. A study using RAPD markers to assess genetic variation within and among Hawaiian populations, found 55 unique genotypes among 56 individuals sampled from six populations on Oahu and Hawaii. This diversity suggests frequent sexual reproduction in these populations. No African populations have been studied so far.

Breeding

There are no known breeding programmes of Heteropogon contortus. While there is considerable genetic variability for selection, there are two serious obstacles to breeding: it is apomictic and it has a most unpractical seed morphology for easy seed production.

Prospects

Heteropogon contortus will remain an important forage in natural grasslands, especially in Africa, Australia, and India. Because of the sharply barbed seed, risk of overgrazing and strongly seasonal growth, careful management is needed. Commercial seed production remains difficult. It is likely to remain a source of thatch and mat-making material of local importance.

Major references

  • Aganga, A.A., Omphile, U.J. & Mojaditlhogo, N., 2005. Composition and digestibility of indigenous grasses in the Hardveld of Botswana during the dry season. Archivos de Zootecnia 54: 587–598.
  • Carino, D.A. & Daehler, C.C., 1999. Genetic variation in an apomictic grass, Heteropogon contortus, in the Hawaiian Islands. Molecular Ecology 8: 2127–2132.
  • Clayton, W.D., Harman, K.T. & Williamson, H., 2002–. GrassBase - the online world grass flora. [Internet] Royal Botanic Gardens, Kew, United Kingdom.http://www.kew.org/ data/grasses-db/. March 2011.
  • Clayton, W.D. & Renvoize, S.A., 1982. Gramineae (part 3). In: Polhill, R.M. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. pp. 451–898.
  • Cook, B., Pengelly, B., Brown, S., Donnelly, J., Eagles, D., Franco, A., Hanson, J., Mullen, B., Partridge, I., Peters, M. & Schultze-Kraft, R., 2005. Heteropogon contortus. [Internet] Factsheet in: Tropical forages: An interactive selection tool. CSIRO Sustainable Ecosystems, Department of Primary Industries & Fisheries, Queensland, Australia, Centro Internacional de Agricultura Tropical, Cali, Colombia and International Livestock Research Institute, Nairobi, Kenya. http://www.tropicalforages.info/key/ Forages/Media/Html/ Heteropogon_contortus.htm. March 2011.
  • Georgen, E. & Daehler, C.C., 2002. Factors affecting seedling recruitment in an invasive grass (Pennisetum setaceum) and a native grass (Heteropogon contortus) in the Hawaiian Islands. Plant Ecology 161: 147–156.
  • Phillips, S., 1995. Poaceae (Gramineae). In: Hedberg, I. & Edwards, S. (Editors). Flora of Ethiopia and Eritrea. Volume 7. Poaceae (Gramineae). The National Herbarium, Addis Ababa University, Addis Ababa, Ethiopia and Department of Systematic Botany, Uppsala University, Uppsala, Sweden. 420 pp.
  • Tothill, J.C., 1966. Phenological variation in Heteropogon contortus and its relation to climate. Australian Journal of Botany 14(1): 35–47.
  • Tothill, J.C., 1968. Variation and apomixis in Heteropogon contortus, Gramineae. Boletin de la Sociedad Argentina de Botanica 12: 188–201.
  • Tothill, J.C. & Hacker, J.B., 2006. Polyploidy, flowering phenology and climatic adaptation in Heteropogon contortus (Gramineae). Austral Ecology 1(4): 213–222.

Other references

  • Burkill, H.M., 1994. The useful plants of West Tropical Africa. 2nd Edition. Volume 2, Families E–I. Royal Botanic Gardens, Kew, Richmond, United Kingdom. 636 pp.
  • Chhetri, R.B., Kumar, N.A. & Kathirvelu, T., 2010. Evaluation of Heteropogon contortus as an alternate source for pulp & paper making. IPPTA Journal 22(2): 95–98.
  • Hendricksen, R.E., Myles, D.J., Reid, D.J. & Orr, D.M., 2010. Impacts of grazing management options on pasture and animal productivity in a Heteropogon contortus (black speargrass) pasture in central Queensland. 3. Diet composition in autumn. Animal Production Science 50(4): 276–283.
  • Hunter, R.A. & Siebert, B.D., 1986. The effects of genotypes, age, pregnancy, lactation and rumen characteristics on voluntary intake of roughage diets by cattle. Australian Journal of Agricultural research 37(5): 549–560.
  • Leithead, H.L., Yarlett, L.L. & Shiflett, T.N., 1971. 100 native forage grasses in 11 southern states. Agriculture Handbook No 389. Soil Conservation Service, U.S. Department of Agriculture, Washington DC, United States. 216 pp.
  • Lowry, J.B., Kennedy, P.M. & Conlan, L.L., 2002. Lignin in the ‘cell contents’ fraction of tropical forages. Journal of the Science of Food and Agriculture 82: 370–374.
  • Melzer, S.E., Knapp, A.K., Kirkman K.P., Smith, M.D., Blair, J.M. & Kelly, E.F., 2010. Fire and grazing impacts on silica production and storage in grass dominated ecosystems. Biogeochemistry 97: 263–278.
  • Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
  • Orr, D.M., Burrows, W.H., Hendricksen, R.E., Clem, R.L., Rutherford, M.T., Conway, M.J., Myles, D.J., Back, P.V. & Paton, C.J., 2001. Pasture yield and composition changes in a Central Queensland black spear grass (Heteropogon contortus) pasture in relation to grazing management option. Australian Journal of Experimental Agriculture 41(4): 477–485.
  • Paswan, V.K., Mahapatra, R.K., Meena, H.R. & Sahoo, A., 2008. Nutrient Composition and Phenolic Constituents in some Feed and Fodder Samples from Temperate Regions of Kumaon Himalaya. Indian Journal of Animal Nutrition 25: 19–24.
  • Piatek, M., 2006. Urocystis skirgielloi, a new graminicolus smut fungus infecting Heteropogon contortus in India. Acta Mycologica 41(1): 7–10.
  • Ripley, B., Frole, K. & Gilbert, M., 2010. Differences in drought sensitivities and photosynthetic limitations between co-occurring C3 and C4 (NADP-ME) Panicoid grasses. Annals of Botany 105: 493–503.
  • Skerman, P.J. & Riveros, F., 1990. Tropical grasses. FAO, Rome, Italy. pp. 446–449.
  • Tefera, S., Dlamini, B.J. & Dlamini, A.M., 2010. Changes in soil characteristics and grass layer condition in relation to land management systems in the semi-arid savannas of Swaziland. Journal of Arid Environments 74: 675–684.
  • Tothill, J.C., 1992. Heteropogon contortus (L.) P. Beauv. ex Roemer & Schultes. In: ’t Mannetje, L. & Jones, R.M. (Editors). Plant Resources of South-East Asia No 4. Forages. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 137–139.
  • Tothill, J.C., Nix, H.A., Stanton, J.P. & Russell, M.J., 1985. Land use and productive potentials of Australian savanna lands. In: Tothill, J.C. & Mott, J.J. (Editors): The ecology and management of the world’s savannas. Australian Academy of Science, Canberra, Australia. pp. 125–144.
  • Vánky, K., 2000. Taxonomical studies on Ustilaginales. XX. Mycotaxon 74(1): 161–215.
  • Wang, B. & Qiu, Y.L., 2006. Phylogenetic distribution and evolution of mycorrhizas in land plants. Mycorrhiza 16: 299–363.
  • Wilson, J.R. & Kennedy, P.M., 1986. Plant and animal constraints to voluntary feed intake associated with fiber characteristics and particle breakdown and passage in ruminants. Australian Journal of Agricultural Research 47(2): 199–225.

Sources of illustration

  • Tothill, J.C., 1992. Heteropogon contortus (L.) P. Beauv. ex Roemer & Schultes. In: ’t Mannetje, L. & Jones, R.M. (Editors). Plant Resources of South-East Asia No 4. Forages. Pudoc Scientific Publishers, Wageningen, Netherlands. pp. 137–139.

Author(s)

  • T. Soromessa, Addis Ababa University, P.O. Box 1176, Addis Ababa, Ethiopia

Correct citation of this article

Soromessa, T., 2011. Heteropogon contortus (L.) P.Beauv. ex Roem. & Schult. [Internet] Record from PROTA4U. Brink, M. & Achigan-Dako, E.G. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. <http://www.prota4u.org/search.asp>.

Accessed 2 March 2020.