Index | Search | Home

new crop logo

Panicum maximum Jacq.

Guineagrass, Hamilgrass

Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.

  1. Uses
  2. Folk Medicine
  3. Chemistry
  4. Toxicity
  5. Description
  6. Germplasm
  7. Distribution
  8. Ecology
  9. Cultivation
  10. Harvesting
  11. Yields and Economics
  12. Energy
  13. Biotic Factors
  14. References


Guineagrass is the most productive forage grass in tropical America, valuable for pasture, green-soilage, hay, and silage. Especially palatable in the younger stages, tending to become coarser and less readily eaten by cattle as it matures. However, because of its lack of good seed production, its use is limited (Reed, 1976). Lately it has been championed as an energy grass. Ingestion of juice from guineagrass is reported to stimulate the movements isolated intestines of goats and other ruminants; addition of a small quantity of the grass to lucerne feed counteracts the inhibitory effects of the latter on intestines and may, therefore, prove useful in preventing tympanitis in cattle (C.S.I.R., 1948–1976).

Folk Medicine

Reported to be diuretic and preventitive, guineagrass is a folk remedy for tympanitis (Duke and Wain, 1981).


Per 100 g, the forage is reported to contain (ZMB): 5.9 g protein, 1.6 g fat, 81.9 g total carbohydrate, 35.7 g fiber, 10.6 g ash, 2090 mg Ca, and 590 mg P (Duke and Atchley, 1984). According to the Wealth of India (C.S.I.R., 1948–1976), the grass is rich in carotene (24–39 mg/100 g) and contains vit. B1 vit. C, and 23.0–34.6 mg/100 g tocopherol. On ZMB, a total ash of 13.9% contained 0.71% CaO, 0.56% P2O5, 2.92% K2O, 0.41% Na2O, and 0.45% MgO. Per 100 g, there are 52.6 mg Fe, 12–31 mg I, 560 mg Cl, and 180 mg S. Phytic acid phosphorus accounted for 30% of total phosphorus. There was 1.5 % oxalates (as oxalic acid, ZMB). Gohl (1981) reports the following:

As % of dry matter
Fresh, vegetative, 40 cm, Tanzania 25.0 8.8 29.9 11.2 1.6 48.5
Fresh, vegetative, 80 cm, Tanzania 25.0 8.8 32.8 12.9 1.5 44.0
Fresh, early, bloom, Tanzania 28.0 5.3 39.6 10.6 1.4 43.1
Fresh, cut at intervals of 1 week, Malaysia 22.0 20.5 24.1 11.4 0.9 43.1
Fresh, cut at intervals of 2 weeks, Malaysia 23.0 14.3 27.4 12.2 0.9 45.2
Fresh, cut at intervals of 3 weeks, Malaysia 23.0 12.6 28.7 13.0 0.9 44.8
Fresh, cut at intervals of 4 weeks, Malaysia 23.0 11.7 30.9 13.0 1.3 43.1
Fresh, cut at intervals of 5 weeks, Malaysia 24.5 10.2 30.6 13.9 0.8 44.5
Fresh, cut at intervals of 6 weeks, Malaysia 25.0 9.6 31.2 13.2 1.2 44.8
Fresh, mature Nigeria 25.7 7.8 33.4 12.2 1.4 45.2
Hay, wet season, 6 weeks, 70 cm, Thailand 83.4 6.8 36.3 11.3 1.8 43.8
Hay, wet season, 8 weeks, 110 cm, Thailand 86.9 7.7 39.0 10.9 1.6 40.8
Hay, wet season, 10 weeks, 170 cm, Thailand 87.3 5.5 40.1 10.8 1.6 42.0
Hay, wet season, 12 weeks. 170 cm, Thailand 86.5 5.5 40.1 10.4 1.4 42.6
Hay, wet season, 6 weeks, 65 cm, Thailand 88.6 11.9 31.7 12.0 3.2 41.2
Hay, dry season, 8 weeks. 70 cm, Thailand 90.8 8.3 35.7 13.0 2.0 41.0
Hay, dry season, 10 weeks, 70 cm, Thailand 89.7 6.6 35.5 13.2 1.8 42.9
Hay, dry season, 12 weeks, 95 cm, Thailand 91.1 7.2 36.4 12.5 2.1 41.8
Silage, Tanzania 20.0 6.3 39.7 19.6 2.7 31.7
Digestibility (%)
Fresh, 40 cm Sheep 64.8 71.6 31.3 67.0 2.23
Fresh, 80 cm Sheep 43.2 73.5 13.3 59.8 2.00
Early bloom Sheep 50.9 63.9 50.0 53.4 1.91
Mature Cattle 60.3 53.0 42.9 65.0 1.95
Hay, 6 weeks Sheep 62.0 58.0 61.0 57.0 1.93
Hay, 8 weeks Sheep 49.0 56.0 53.0 49.0 1.74
Hay, 10 weeks Sheep 36.0 58.0 47.0 54.0 1.80
Silage Sheep 34.9 82.4 40.7 51.7 1.95


In South Africa, it is suspected to cause a sheep disease ("dikoor"), perhaps in conjunction with a smut. The plant is said to cause fatal colic if eaten too wet or in excess. Traces of HCN occur in stems and leaves, more in the roots.


Tufted perennial grass, usually in large bunches from short stout rhizomes, 1–3 m tall; culms erect, stout; nodes usually densely hirsute; sheaths papillose-hirsute to glabrous, usually densely pubescent at the collar; ligule 4–6 mm long; leaves flat, bright green, 15–76 cm long, 1–3.5 cm wide, glabrous on margins, sometimes hirsute on upper surface; panicle rather loose, erect or nodding, 15–50 cm long, about one-third as wide, with 3–7 whorled lowermost branches; spikelets 3–4 mm long, awnless, green or tinged with purple, with 2 florets of which only the upper is fertile; first glume about one-third the length of spikelet; mature upper floret (seed) white, not glossy. Seeds 1.7–3.1 million/kg.


Reported from the African Center of Diversity, guineagrass, or cvs thereof, is reported to tolerate drought, grazing, light frost, low pH, phages, shade, slope, virus, waterlogging, and weeds. Many local cvs and strains have been developed: 'Coloniao' grows to 3 m; 'Sabi', to 1 m tall. 'Common guinea' is the ordinary robust type; 'Slender guinea' or Green panicgrass (P. maximum var. trichoglume Eyles = P. maximum var. pubiglume K. Schum.), is more slender, smaller, with finer leaves, is mainly grown in Queensland and combines well with luceme, usually used for pasture grass; 'Purpletop guinea' (P. maximum var. coloratura) is a low, rather coarse variety, suitable for grazing. 'Siempre-verde' (P. maximum var. gongylodes Doell, P. bulbosum) is fine leaved, drought-resistant form with base of culms expanded into bulbs, and is mainly used for grazing. In Puerto Rico, 'Local', 'Gramalote', 'Borinquen', 'Broadleaf', and 'Fine Leaf', are grown; 'Local' is resistant to drought and heavy grazing and is grown in drier areas. In Jamaica, 'Silk Guinea' is a very leafy type for drier areas; 'St. Mary's cowgrass' is more robust and stemmy and is grown in more humid areas. Several cvs have been developed in Brazil and Hawaii. (2n = 18, 36, 32). (Reed, 1976; Duke, 1978.)


Indigenous to Africa; introduced, cultivated, and now naturalized in many tropical and subtropical areas of the world. Also introduced in south Florida and California (Reed, l976). Like so many energy species, especially energy grasses, this has been considered a serious or principal weed (in Australia, Bermuda, Costa Rica, Cuba, Ecuador, Ghana, Hawaii, Jamaica, Mexico, Mozambique, Puerto Rico, South Africa, Swaziland, Tanzania, Trinidad, Uganda, and Venezuela) (Holm et al., 1979).


Ranging from Warm Temperate Dry to Moist through Tropical Very Dry to Wet Forest Life Zones, guineagrass is reported to tolerate annual precipitation of 6.4 to 42.9 (mean of 40 cases = 18.5), annual temperature of 12.2 to 27.8°C (mean of 40 cases = 23.4), and pH of (3.5-)4.3 to 8.4 (mean of 33 cases = 5.9) (Duke, 1978, 1979). Grows naturally in open grasslands, usually forming colonies under or near trees and shrubs, frequent in woodland bush thickets, and on abandoned cultivated land, fields and on waste lands, from sea level to 2,160 m in East Africa. Suited to areas with annual rainfall from 87 to 100 cm. With sufficient moisture, plants grow extremely rapidly, providing much biomass. Grows well on a wide variety of well-drained soils. Does not thrive in areas subject to prolonged waterlogging or flooding, nor on saline soils. Not resistant to more than an occasional light frost. Somewhat tolerant to shade and grows under trees or in stands of low bush. Grows in moderately dry ground and is drought-resistant, but will not tolerate dry periods longer than 4 months.


Although plants seed readily, heads ripen very unevenly and shatter readily. Hence seed must be hand-collected. Viability of fresh seed is comparatively low. It is increased by storing seeds dry for 6 months or longer. Seed viability under natural conditions is short-lived. Crop should be allowed to reseed itself at periodic intervals to insure stand maintenance. When plants are allowed to seed themselves, this grass is the first to appear on newly cleared land or scrubland. Land is usually prepared by repeated plowing and disking. Seed broadcast at 4–12 kg/ha or more, and 4–9 kg/ha or more when planted in rows. Crops may also be established by propagating by sprigs, or by dividing the stools. However, it is more economical and practical to establish the crop by seeding. Small areas are often hand-planted by using these divided crowns. It tillers profusely, producing tufts or clumps up to 30 cm or more wide. Preemergence weed control measures are usually beneficial in stand establishment (Reed, 1976). Liming acid peat (pH 3.47) up to 12 MT lime/ha increased DM yields quadratically up to pH 4.2. Liming decreased the N, P, and K, but increased the Ca and Mg contents of the harvested grass (Chew et al., 1980).


Produces abundant shattering seed, the heaviest crop during the wet season, a lighter crop during spring and summer. Crop may be mown for green soilage, hay or silage, at six week intervals during growing season at height of 15–24 cm. Rotational grazing is essential if continuous production of young leafy herbage is to be maintained. Plants die rapidly under close continuous grazing. In tropical Queensland, it grows well with tropical perennial legumes as centro (Centrosema pubescens); in Puerto Rico, with tropical kudzu (Pueraria phaseoloides); in Hawaii, with Desmodium sp. and Indigofera endecaphylla. Molassasgrass is sometimes grown with guineagrass to give a rapid ground cover. Mixtures with centro have been maintained for 7 years, under a system of 7-day grazing followed by 28 days rest; 15–24 cm growth should be maintained on the pasture. Seed set should be allowed every 2 years to fill gaps in stand. Deteriorating stands can be renovated by natural seeding, disking, or shallow plowing, or burning the old growth (Reed, 1976).

Yields and Economics

Green matter yields of 87 MT/ha per annum have been obtained from unfertilized stands; on well manured or fertilized stands, 125–150 MT/ha green fodder has been obtained per annum. Seed yields fluctuate greatly. This grass is of primary economic importance in many tropical countries, including East Africa, Hawaii, Virgin Islands, Puerto Pico, and South America.


According to the phytomass files (Duke, 1981b), annual productivity ranges from 1 to 50 MT/ha, DM, with NPP of 3 MT/ha/yr in Bolivia, 1–27 in Brazil, 6–50 in Colombia, 4–19 in Cuba, 14 in French Guiana, 1–40 in India, 30 in Nigeria, 25 in Peru, 47 in Puerto Rico, 4–7 in Sri Lanka, 14–24 in Taiwan, 20 in Thailand, and 8–12 in Uganda. DM yields in other Panicum species are 1–30 in Panicum antidotal, 2–23 in P. coloratura, 11 in P. hemitomum, 6–21 in P. repens, and 9 in P. virgatum.

Biotic Factors

There has been much attention, perhaps overdue, to N-fixation by guineagrass in symbiosis with the N-fixing bacterium Spirillum lipoferum. Bouton (1976) suggested that bacterial inoculation might save ca 30–40 kg/ha N. Following fungi are reported: Apiospora camptospora, Aulographum panici-maximi, Balansia claviceps, Cercospora fusimaculans, Cerebella andropogonis, C. panici, Claviceps maximensis, C. purpurea, Coniothyrium panici, Corticium solani, Fusarium heterosporum, F. oxysporum, Helminthosproium flagelloideum, H. panici, H. sativum, Leptosphaeria recutita, Nigrospora sphaerica, Otthia panici, Papularia sphaerosperma, Periconia digitata, P. lateralis, Periconiella echinochloae, Phyllachora heterospora, Phyllosticta panici, P. panici-maximi, Physopella cameliae, Puccinia levis, P. leacadis, P. panici, Pythium aphanidermatum, Rhizoctonia solani, Sclerophthora sp., Sorosporium panici, Tilletia ayresii, and Uromyces graminicola. It is also attacked by the bacterium Pectobacterium carotovorum var. graminarum and by the parasitic flowering plants Striga gesnerioides and S. lutea. Nematodes isolated from guineagrass include: Boleodorus thylactus, Helicotylenchus dihystera, H. pseudorobustus, Hemicriconemoides cocophilus, Hemicycliophora paradoxa, Pratylenchus brachyurus, P. zeae, Radopholus similes, Rotylenchus brevicoaudatus, Scutellonema clathricaudatum, Tylenchorhynchus annulatus, and Xiphinema longicaudatum. Guineagrass is susceptible to various crop pests, including: Acrosternum marginatum, Oebalus pugnax, Petrusa epilepsis, Euschistus crenator and Spodeptera frugiperda. On occasions these insects cause serious damage to crop, resulting in decrease in yield and quality of forage (Reed, 1976).


Complete list of references for Duke, Handbook of Energy Crops
Last update Wednesday, January 7, 1998 by aw