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This page is copied from Lazarides (2002). The nomenclature is updated.
Introduction
Food Grasses
Fodder Grasses
Rangelands
Cover Grasses
Grass Weeds
Poisonous Grasses
Physically Harmful Grasses
Ethnobotanical Uses of Grasses
Ornamental Grasses
Honey and Pollen Grasses
Miscellaneous Uses
Grasses Causing Human Ailments
Conclusion
References
Introduction
Grasses are among the most versatile groups of plants in terms of their adaptation to a wide range of climatic and edaphic conditions. The family is also highly successful due to its adaptability to changing environments, its potential for diversity and variation and its ability to coexist with grazing herbivores and humans. In this respect, perennating buds occur just above the soil surface (in tussock grasses), at the surface (in stoloniferous grasses) and just below the surface (in rhizomatous grasses). They are relatively inaccessible to grazing, and new shoots (tillers) with independent adventitious root systems are produced freely to replace the loss of any aerial parts.
In Australia, there are approximately 1320 introduced and indigenous grass entities in about 234 genera. Of these, 35 genera are endemic, 130 include indigenous and introduced species, and 69 genera are wholly introduced.
Food Grasses
Undoubtedly, the outstanding economic attribute of the Poaceae is their provision of food for humans. All of the winter cereal grasses, comprising Triticum aestivum (Wheat), Secale cereale (Rye), Hordeum vulgare (Barley), Zea mays (Maize), Avena sativa (Oats) and Panicum miliaceum (Millet Panic), as well as the other staple foods of warm regions, Oryza sativa (Rice) and Saccharum officinarum (Sugarcane), are grown in Australia. Apart from these basic food grasses, the grain of a large number of other species are eaten in times of famine by peoples in developing countries. Many of these grasses, including species of Eleusine (Indian Millet), Eragrostis (Lovegrass), Echinochloa (Barnyard Grass), Setaria (Pigeon Grass), Brachiaria (Armgrass), Dactyloctenium (Button Grass) and Oryza rufipogon (Red Rice), also grow in Australia and are potential food plants for humans and their domestic animals. Similar to other indigenous peoples, Australian Aborigines utilise native grasses and other plants for food.
Grasses also play a very significant role as food for domestic animals and native fauna. Of major value are the grain sorghums, Maize and Rye, the grain of which is used in the preparation of stock feed and concentrates. The grain of Panicum miliaceum is widely used as a food for poultry, pigs and caged birds. Other suitable birdseed species include Setaria italica (Foxtail Millet ), S. pumila (Pale Pigeon Grass), Echinochloa frumentacea (Siberian Millet), E. utilis (Japanese Millet) and Phalaris canariensis (Canary Grass). The small seeds of Imperata cylindrica (Blady Grass) are eaten by emus and kangaroos, and the large maize-like grain of Chionachne hubbardiana and C. cyathopoda (River Grass) provides a major part of the diet of many large birds. The seeds of Alloteropsis semialata (Cockatoo Grass) are readily eaten by cockatoos, while wallabies dig out and eat the nut-like roots of Chrysopogon fallax (Golden-beard), and the corms of Arrhenatherum elatius var. bulbosum (Bulbous Oatgrass) are relished by pigs (Barnard, 1964; Leigh & Mulham, 1965; Lazarides, 1970; Cunningham et al., 1981; McIvor & Bray, 1983).
Fodder Grasses
The great diversity of climate, rainfall, soil type, topography and pastoral regimes in Australia is reflected in the diversity of grass species utilised as stock fodder. Consequently, the phytogeographic regions, which can be broadly classified into monsoonal tropics, arid and temperate, are characterised by different and usually unrelated groups of native and introduced fodder species.
In the monsoonal tropics with its short wet season and long rainless hot dry season, the predominant native grasses are long-lived tussock-forming perennials. These grow vigorously in the wet season and provide palatable nutritious fodder. In the dry season, they become dormant and rank, and are unpalatable or only moderately palatable and low in nutritive value. The most important of the native open-range fodder grasses are species of Astrebla (Mitchell Grass), Bothriochloa (Bluegrass) and Dichanthium (Bluegrass). These occur in extensive areas on the less infertile heavy-textured soils and cracking clay plains of northern Australia. Perennial species of Sorghum (Sorghum), Chrysopogon, Enteropogon (Curly Windmill) and Panicum are less dominant and have lower fodder value. The wet season also produces a variety of annual and short-lived perennial grasses such as species of Iseilema (Flinders Grass), Enneapogon (Nineawn), Tripogon (Five-minute), Tragus (Small Burrgrass) and Sporobolus (Dropseed), which can be sufficiently nutritious for short periods to fatten stock.
In the open rangelands of the arid and semi-arid regions, species of Triodia (Spinifex) predominate over extensive areas of infertile sandy and skeletal soils. These are tough xerophytic grasses grazed when green and in association with better-quality herbage and browse plants, but are chiefly important as drought reserves and subsistence fodder. The more palatable species include Triodia pungens (Soft Spinifex), T. schinzii (Feathertop Spinifex), T. irritans, T. bitextura (Curly Spinifex) and T. mitchellii (Buck Spinifex), and their seedheads and young shoots are eaten by stock. Burning is a regular practise in the management of rangelands in order to promote new growth and the regeneration of softer grasses. Associated more palatable and nutritious grasses include species of Eragrostis, Eriachne (Wanderrie), Monachather (Bandicoot) and Thyridolepis (Mulga Grass). In general, these are drought-resistant plants responding to winter and summer rainfall, and are highly suited to the arid region with its long dry periods and irregular rainfall in any season.
A few species have been introduced in specific habitats of the tropical and arid regions for pasture improvement and rehabilitation purposes. An early introduction, Cenchrus ciliaris (Buffel Grass), is now widely naturalised as a fodder and rehabilitation plant as a result of deliberate introductions and the breeding of cultivars. Megathyrsus maximus (Guinea) is another valuable pasture grass; the typical variety occurs in wet-tropical and subtropical areas, while M. maximus var. pubiglumis (Green Panic) is found in slightly drier subcoastal areas. The hybrid Sorghum ×almum (Columbus Grass) is now sown as a pasture grass and forage crop, and Chloris gayana (Rhodes Grass) is widely sown for fodder due to its drought and salt tolerance, and also its stoloniferous soil-binding habit.
In general, the fodder grasses of the temperate regions are more palatable and nutritious than those of the arid and tropical areas; this is largely due to the prevalence of better-quality soils and less severe climate. In addition, the cultivation of pasture grasses for hay, ensilage or rotational grazing is possible due to a reliable rainfall and available water for irrigation. Of the native winter-spring growing pastures, the Wallaby Grasses (Rytidosperma), Austrostipa (Speargrass) and Poa include some of the most important fodder grasses of temperate and semi-arid areas in southern inland Australia. Poa also includes valuable introduced species such as P. pratensis (Kentucky Bluegrass) and P. bulbosa (Bulbous Poa). In moist temperate regions, Lolium perenne (Perennial Ryegrass) and allied species which have been naturalised or deliberately introduced are equally important fodder grasses under natural rainfall or irrigation. Avena includes introduced annuals which are useful pasture and hay grasses. As well as a valuable cereal, Zea mays is used green or as ensilage for stock fodder. Similarly, Sorghum can be sown for grain, pasture, forage crop and ensilage. Other important fodder grasses of temperate regions include Microlaena stipoides (Weeping Grass), Dactylis glomerata (Cocksfoot), Phalaris aquatica (Phalaris), Festuca arundinacea (Tall Fescue), Puccinellia spp. (Marsh Grasses) and Themeda triandra (Kangaroo Grass).
Table 1 records the forage values for crude protein, phosphorus and digestibility of some Australian grasses. In general, forage with less than 8% crude protein and less than 50% digestibility is insufficient for herbivore maintenance. The data represent typical analyses, but could vary with different climatic, rainfall, and seasonal and edaphic conditions.
Table 1. Forage value of Australian grasses
Plant Name Crude Protein (%) Phosporus (%) Digestibility (%) Region
Aristida contorta 8-10 (green) . . arid
Astrebla elymoides 7 (green), 1.5-3 (dry) 0.4-0. 8 33-43 tropical
Astrebla pectinata 10-12 (green), 4-5 (dry) 0.4-0.9 36-38 tropical
Austrostipa scabra up to 6 . . arid, temperate
Brachyachne convergens 8.6 (green), 3 (dry) 0.1-0.4 35-60 tropical
*Cenchrus ciliaris 8-16 % (green), 2-4 (dry) 0.3-12 70 tropical
Cenchrus setiger 14 (green), 3-4 (dry) 0.2-0.4 . tropical
Chrysopogon fallax 9 (green), 3 (dry) 0.3-0.8 35-60 tropical
Dichanthium fecundum 10 (green), 3.7 (dry) 0.5-0.7 60-76 tropical
Dichanthium sericeum 15 (green), 6 (dry) 0.4-0.6 . tropical
Enneapogon polyphyllus 10.8 (pre-flower) . . arid, tropical
. 2-4 (most of year) 0.4-0.9 36-40 .
Eragrostis eriopoda 10 (green), 4 (dry) . . arid, tropical
Eragrostis lanipes to 16 . . arid
Eriachne flaccida 6 (mature) . . arid, tropical
Eriachne obtusa 4 (green) . 27-38 arid, tropical
Heteropogon contortus 4.5 (green), 2 (dry) 0.2-0.6 . tropical
Iseilema vaginiflorum 9 (green), 2 (dry) 0.2-10 37-62 tropical
Monachather paradoxus 15 (when growing) . . arid, temperate
Sarga plumosum 7 (green), 2 (dry) 0.2-0.8 35-38 tropical
Sehima nervosum 4 (green) 0.1-0.9 . tropical
Themeda triandra 5.8 (green), 1.2 (dry) 0.2-0.7 30-50 temperate, tropical
Thyridolepis multiculmis to 16 (green) . . arid
Triodia bitextura 6 (seedlings), 2 (mature) 0.3-0.5 26-35 arid, tropical
Triodia pungens 10 (seedling), 7-11 (young), 5 (at 6-8 months),
4-5 (at 5 years) . . arid, tropical
Triodia schinzii 10 (young), 3 (old) . 35 (young), 25 (old) arid, tropical
*Urochloa mosambicensis 14 (green), 4 (dry) . . tropical, warm-temperate
* signifies introduced taxa
(Source: Petheram & Kok, 1983)
These data represent typical analyses but could vary with different climatic, rainfall, seasonal and edaphic conditions.
Rangelands
In Australia, vast areas of native grasslands and shrublands are utilised as open rangelands for sheep and cattle grazing. Often, such areas are characterised by low or irregular rainfall, a seasonally arid climate, infertile (sometimes saline) soils and a lack of permanent surface water. Stocking rates are low, and are determined by the availability of basic fodder and water. The properties are either unfenced or fenced into large paddocks. Water for stock is pumped from bores and wells or collected in earth dams. Limited financial return and extensive areas usually preclude improvements such as the application of fertilisers and pasture improvement schemes.
To achieve optimum long-term utilisation in this environment, sound rangeland management is critical to maintain soil and plants in a balanced, stable and productive condition. Poor practices lead to instability of the landscape, domination by unpalatable plants, loss of soil and the shedding rather than the absorption of rainfall.
All rangeland plants are adapted to withstand long dry periods, and on the basis of their means of survival, they can be classified as follows:
1. Perennial drought-resistant plants
These plants usually remain in a dormant state during drought, and resume growth with the onset of favourable conditions. They are dominated by woody species (trees and shrubs), but include sclerophyllous evergreen hummock grasses, especially Triodia spp., which are shrub-like in their adaptation to drought.
2. Perennial drought-evading plants
Some or all of the aerial parts of the plant die when available moisture is exhausted. However, after rain, new growth (culms, leaves or inflorescences) develops from basal and axillary buds on rhizomes and old tillers. Generally, seed set is low and regeneration is chiefly from vegetative buds. Seedlings are probably produced only when plants die completely or are destroyed by burning, or during extremely favourable conditions which encourage germination by reducing competition from other plants for soil moisture and nutrients.
Woody plants in this group are deciduous trees and shrubs, but the most significant component are long-lived perennial and mostly medium-sized tussock grasses such as species of Astrebla, Bothriochloa, Chloris, Chrysopogon, Dichanthium, Enteropogon, Panicum and Sorghum s. lat.
3. Short-lived drought-evading plants
These plants survive long dry periods as seeds, and only grow after rain. The group comprises a large number of short grasses and forbs of varying duration as ephemerals, annuals or short-lived perennials (biennials). The ephemerals and annuals include numerous species in many genera such as Iseilema, Tragus and Perotis (Cornet Grass), which complete their life cycle in one season. Species of Enneapogon, Tripogon, Chloris, Sporobolus and other genera persist for more than one growth season as short-lived perennials by regenerating from small rootstocks during successive favourable periods.
Certain plant species are indicators of rangeland condition. Thus, the presence of desirable plants having palatability, drought resistance and persistence, but which disappear under mismanagement, indicate good range condition and may be termed 'decreaser species'. By contrast, 'increaser species' are those which replace decreaser species, and they are usually less palatable or worthless and thus indicate poor range condition. Pastures in good condition contain over 50% decreasers, those in fair condition 30-50%, and in poor condition 5-30%. Very poor condition is indicated by less than 5% decreasers and over 65% increasers and unpalatable weedy invaders. Not all plants have indicator value, and some species can be decreasers in one rangeland type, but increasers in another. Also, in assessing rangeland condition, it is more accurate to use as many species as possible.
Cover Grasses
This group of grasses is among the most valuable, as it fulfils the important function of preventing or reducing the loss of soil by wind and water erosion. Moreover, cover plants conserve moisture by shading soil and water surfaces, thus reducing loss to the atmosphere from evaporation.
Perennials particularly rhizomatous and stoloniferous species, are more effective than annuals as soil binders and cover plants, due to the development of fibrous roots and rootlets (as well as rhizomes) and/or their spreading mat-forming habit. A noteworthy native example is Chrysopogon, which protects against soil erosion by its vigorous deep rooting system and persistent basal leaf-sheaths. An introduced species, the well-known Cenchrus ciliaris, was extremely useful in the revegetation of the Ord River Scheme in Western Australia.
However, heavy-seeding rapidly growing annuals and short-lived perennials also serve a useful purpose by providing a dense protective plant cover for limited periods. In the wet season, Iseilema spp. grow densely in the bare interspaces between perennial tussocks on the Astrebla-Bothriochloa-Dichanthium-dominated black soil plains of the Barkly Tableland in Queensland and similar areas. Tripogon loliiformis colonises denuded and disturbed ground on steep slopes, while Digitaria bicornis is also a coloniser of bare areas and interspaces. Brachyachne spp. (Native Couch) are pioneer species on gravelly and eroded areas, and Ectrosia schultzii is another pioneer heavy-seeding species. Salt-tolerant Xerochloa spp. are pioneer and colonising plants on coastal salt flats and inland clay plains. In the dry season, Sporobolus actinocladus (Katoora) protects floodplains against wind erosion, while Eragrostis falcata (Sickle Lovegrass) is a protective soil binder against wind and water erosion.
Sandy coastal habitats are among the areas that are most susceptible to wind erosion and disturbance (Carolin & Clarke, 1991). Hardy salt-tolerant species such as Distichlis distichophylla (Australian Saltgrass), Spinifex spp. (Heyligers, 1988), Sporobolus virginicus (Sand Couch), Zoysia macrantha (Prickly Couch), and the introduced Austrofestuca littoralis (Coast Fescue), Ehrharta villosa (Pyp Grass), Ammophila arenaria (Marram Grass) and Parapholis incurva (Coast Barbgrass) are successful soil stabilizers on beaches, foreshores, dunes and salt meadows. On tropical coasts, Aristida contorta (Bunched Kerosene Grass), Chloris virgata (Feathertop Rhodes), Eulalia aurea (Silky Browntop), Triraphis mollis (Purple Plume), Whiteochloa airoides, Eriachne gardneri, Eragrostis spp. and Triodia spp. are useful cover plants on dunes, tidal mudflats and plains (Craig, 1983). On the loose sands of inland sandhills and dunes, Zygochloa paradoxa (Sandhill Canegrass) and Eragrostis laniflora (Woollybutt) are excellent sand binders against wind erosion.
Cover grasses include a wide range of chiefly introduced species suitable for lawns and as turf for sports grounds, golf courses, tennis courts, bowling greens, parks and similar recreational areas. Cynodon dactylon (Couch) and cultivars are among the hardiest of the lawn, turf and erosion control grasses and are widely used in residential and urban areas where water conservation is a priority. Digitaria didactyla (Queensland Blue Couch) is a common lawn grass which has been naturalised in south-eastern Queensland and coastal areas of New South Wales and Western Australia for over 100 years. Axonopus fissifolius (Narrow-leaved Carpet Grass) and A. compressus (Broad-leaved Carpet Grass) are stoloniferous lawn grasses especially suitable in sandy coastal soils, and Zoysia macrantha is a stoloniferous and rhizomatous lawn grass and sand binder suitable for similar conditions. An allied species, Zoysia tenuifolia, is a fine-leaved plant excellent for lawns, golf courses and tennis courts. Cenchrus clandestinus (Kikuyu) is a vigorous densely mat-forming lawn grass tolerant to hot dry weather and saline soils. Stenotaphrum secundatum (Buffalo Grass) from the U.S.A. is a widespread forage, turf and lawn grass in all states except the Northern Territory), and is sometimes a weed. Winter and spring-growing lawn and turf species suitable in temperate areas include the stoloniferous Agrostis stolonifera (Creeping Bent), Lolium perenne (Perennial Rye), Poa pratensis (Kentucky Bluegrass), a valuable turf species from North America, and P. bulbosa (Bulbous Poa), a golf course cover grass which grows from bulbils and withstands dry conditions and saline soils.
Some cover grasses also have valuable shelter uses. The morphologically variable Themeda triandra is a parent species for the breeding of strains, cultivars and varieties suitable for the revegetation, screening and beautification of median strips and road verges. The native Rytidospermum richardsonii (Wallaby Grass), used in the revegetation of roadside corridors, has many advantages and few disadvantages over introduced species used currently (Lodder et al., 1986; Jefferson et al., 1991). Arundo donax (Giant Reed) is a robust clump-forming semi-aquatic useful for wind-breaks, while a common plant of inland clay pans and salt lakes with similar habit, Eragrostis australasica (Canegrass), provides breeding shelter for native fauna and protection against wind and water erosion.
A number of aquatic and semi-aquatic grasses prevent erosion by water and serve other useful purposes. Phragmites spp. (Reeds) are versatile amphibious plants which prevent wave and current erosion in channels and on stream and lake edges, and while they form reed beds in which water birds and other animals thrive, dense infestations in irrigation canals can cause silting and reduce water flow. Similarly, Leptochloa digitata (Umbrella Canegrass) can be troublesome in irrigation, but also useful in soil conservation. Although not aquatic, Arundinella nepalensis (Reed Grass) is a fringing species of watercourses high in bulk, which reduces stream bank erosion (Sainty & Jacobs, 1981, 1988).
Grass Weeds
In the Australian grass flora, approximately 374 species and infraspecific taxa in 113 genera are designated as weeds. The chief criteria applied in determining their weedy status include the plant's detrimental impact on crops, pastures and the native environment, its toxic and physically harmful effects on domestic stock, and the extent of its naturalisation. The term is applied broadly to include deliberate and accidental introductions and indigenous species, which have become invasive due to environmental disturbance. However, this latter group, the invasive natives, predominantly comprise woody shrubs and trees such as Acacia and Senna rather than grasses. For general references see Carolin & Clarke (1991) and Lazarides et al. (1997).
Weedy grasses include those of the native environment, cultivation, irrigation, horticulture, recreational areas and disturbed areas. In terms of weedy status or importance, they range from occasional garden escapes with little or no economic or aesthetic impact to declared noxious weeds such as Andropogon virginicus (in parts of New South Wales), Cenchrus spp. (in many States), Cortaderia spp. (in Tasmania and parts of New South Wales), Eragrostis curvula (in many States), Glyceria maxima (in Tasmania), Nassella spp. (in many States), Oryza rufipogon (in the Northern Territory and Queensland), Paspalum quadrifarium (in parts of New South Wales), Pennisetum (now in Cenchrus) spp. (in many States), Phyllostachys aurea (in parts of New South Wales), Setaria verticillata (in one part of New South Wales), Sorghum halepense (in the Northern Territory and parts of New South Wales) and Sporobolus fertilis (in parts of New South Wales) and S. pyramidalis (in Queensland and parts of New South Wales). However, the official status of declared noxious weeds may vary in time and between jurisdictions; therefore, this list applies only at the time of writing.
Not all weeds are detrimental at all times. Often, weedy characteristics are offset to some degree by favourable qualities such as fodder, cover or ornamental value. A species might be regarded as a weed in one environment and at one period, but as a useful plant in other circumstances. Examples include Ammophila arenaria (Marram Grass), a valuable coastal sand binder, but sometimes an invasive weed of native species, or Arrhenatherum elatius (False Oatgrass), chiefly a weed of crops, but sometimes a useful fodder plant and ornamental. Bromus catharticus (Prairie Grass), cultivated under irrigation as a pasture grass, is also a weed of orchards and gardens, and sometimes nitrate-toxic.
Most Australian grass weeds are accidental introductions which have become naturalised. Most of the winter and spring-growing species of southern Australia originated in temperate Europe and Asia and the Mediterranean region, while those summer-growing species which are a problem in northern Australia came mainly from Africa and tropical America. Comparatively few species originated in tropical Asia or are native and widespread in the Paleotropics (Sainty & Jacobs, 1981, 1988).
Serious grass weeds include rhizomatous or stoloniferous aquatic and semi-aquatic species (Aston, 1973), which can be dispersed by water-borne seed, rhizomes or stem fragments. Such weeds thrive in irrigated crops, wetlands, waterways and channels, and include Glyceria maxima (Reed Sweet Grass), Oryza rufipogon (Red Rice), Panicum repens (Torpedo Grass), Paspalum spp., Pennisetum spp., Phalaris spp. (Canary Grass), Phragmites spp. (Reed), and Polypogon spp. (Beardgrass). Spartina (Cordgrass), a genus of maritime rehabilitation weeds, forms extensive meadows on tidal mud flats, salt marshes and in mangrove communities.
Poisonous Grasses
The Poaceae contain many toxic or potentially toxic species, some of which are also valuable forage crops and pasture plants. Many species have given positive tests for prussic acid (HCN) or nitrate, and some can accumulate oxalates in potentially toxic amounts. For general references see Hurst (1942), Gardner & Bennetts (1956) and Everist (1981).
A number of factors influence grass toxicity. One of the most important is an animal's condition, hungry animals in poor condition being the most susceptible to poisoning. Moreover, losses are more likely to occur in stock subjected to to the stresses of mustering, droving or yarding, or in holding stock after a period of starvation.
The condition of the plant often influences the quantity of toxin present and its palatability, and therefore the amount consumed. Prussic acid and soluble oxalates accumulate in young shoots, whereas nitrate is concentrated in the stems (usually the lower parts) and mature leaves. In addition, all or only some parts of a plant can be toxic, and toxicity can be present at any stage in growth; some species are toxic as seedlings and not at maturity, while in others, the converse applies.
Weather conditions can affect levels of toxicity, so that plants containing prussic acid tend to be more dangerous under light rainy conditions than in dry weather. Acute phalaris poisoning from increased amounts of alkaloids occurs most commonly under foggy, cloudy or frosty conditions, during high temperatures or in the early morning. Similarly, factors such as low light intensity, hot or dry days and wilting favour the accumulation of nitrates, which are often reduced to highly toxic nitrites.
Plant-soil relationships can be relevant to toxicity. Some plants accumulate metallic poisons and are most likely to be toxic when growing in soils rich in these elements. Soils which are nitrogen-rich but deficient in other minerals can influence toxicity in plants. Similarly, heavy applications of nitrogenous fertiliser to Phalaris (Canary Grass) pastures can increase the level of alkaloids in the plant and the risk of poisoning.
Table 2. Poisonous grasses in Australia
Plant Name Toxin/Symptoms Affected Stock Region
*Avena sativa (Oats) nitrates/nitrites dairy cattle temperate
*Urochloa decumbens (Signal Grass) & *U. brizantha oxalates/ photosensitisation experimental sheep tropical, warm-temperate
Urochloa gilesii (Hairy-edged Armgrass) oxalates/nitrates Sheep tropical, warm-temperate
*Urochloa mutica (Para Grass) oxalates horses tropical, warm-temperate
Brachyachne convergens (Common Native Couch) HCN sheep, horses, calves tropical
Chloris truncata (Windmill Grass) HCN tests strongly positive; no field reports tropical, arid, temperate
. hepatogenous photosensitisation Merino lambs .
Chloris ventricosa (Tall Chloris) HCN tests strongly positive; no field reports tropical, arid, temperate
Cynodon dactylon (Couch) HCN cattle, sheep tropical, arid, temperate
*Cynodon nlemfuensis (Bermuda Grass) HCN chiefly cattle tropical, warm-temperate
*Cynodon incompletus (Blue Couch) HCN sheep and cattle, particularly young animals and travelling stock tropical, warm-temperate
Dactyloctenium radulans (Button Grass) probably nitrates cattle, sheep; particularly young sheep and rams tropical, arid, temperate
*Digitaria didactyla (Queensland Blue Couch) & *D. eriantha (Woolly Finger Grass) oxalates under certain conditions may cause chronic oxalate intoxication in horses; no reports in literature tropical, warm-temperate
*Echinochloa esculenta (Japanese Millet) . suspected of poisoning lambs tropical, temperate
*Echinochloa crus-galli (Barnyard Grass) nitrates . tropical, arid, temperate
Echinopogon spp. (Hedgehog Grass) unknown sheep, cattle, goats, particularly lambs and calves temperate
*Eleusine indica (Crowsfoot) HCN in all parts of plant at all times except winter; also nitrates sheep; reported cases rare tropical, arid, warm-temperate
*Eustachys distichophylla (Evergreen Chloris) HCN toxic; no field reports tropical, arid
*Festuca arundinacea (Tall Fescue) mycotoxins cause of 'fescue foot' in dairy cattle temperate
*Hordeum vulgare (Barley) nitrates toxic in pigs in U.S.A., but not in Australia temperate
*Lolium multiflorum (Italian Rye) nitrites reports of poisoning in calves in New Zealand temperate
*Lolium perenne (Perennial Rye) 'ryegrass staggers' sheep, cattle, horses, especially young animals temperate
. facial eczema sheep, cattle .
*Lolium rigidum (Annual Rye) uncertain chiefly sheep, also cattle temperate
*Lolium temulentum (Darnel or Drake) uncertain (fungus sometimes present in seed) 'weed Darnel' in humans in Europe and U.S.A.; chiefly horses, dogs and pigs; also ruminants and birds temperate
*Panicum antidotale (Blue Panic) oxalates potentially poisonous to ruminants and horses under certain conditions tropical, warm-temperate
*Panicum coloratum (Coolah Grass) oxalates potentially poisonous to horses under certain conditions tropical, temperate
. photosensitisation Merino lambs .
Panicum decompositum (Native Millet) suspected photosensitisation sheep tropical, arid, temperate
Panicum effusum (Hairy Panic) photosensitisation cause of 'yellow big head' in sheep, pigs tropical, arid, temperate
*Megathyrsus maximus (Guinea Grass) and *M. maximus. var. pubiglumis (Green Panic) HCN, cyanide tests positive; no field reports tropical, warm-temperate
. oxalates horses .
*Panicum miliaceum (Millet Panic) photosensitisation lambs tropical, temperate
Panicum queenslandicum (Yabila Grass), *Panicum schinzii, P. laevinode (Pepper Grass) photosensitisation most livestock tropical, temperate
*Paspalum dilatatum (Paspalum), *P. distichum (Saltwater Couch) seedheads parasitized by ergot fungus cause of ergot poisoning in cattle; also in sheep and horses; reports of children becoming ill after chewing infected heads. . tropical, temperate
*Cenchrus ciliaris (Buffel) oxalates horses tropical
*Cenchrus clandestinus (Kikuyu Grass) nitrates-nitrites cattle, pigs tropical, arid, temperate
. oxalates horses
. 'Kikuyu poisoning' cattle .
*Phalaris aquatica (Phalaris) alkaloids ('Phalaris staggers') sheep, cattle temperate
. oxalates cattle, horses .
Setaria spp. (Cultivars of *S. anceps, *S. sphacelata and *S. trinervia; Pigeon Grasses) oxalates cattle, horses tropical, warm-temperate
Sorghum spp. s. lat. (Sorghum) HCN, nitrates chiefly cattle (including dairy) tropical
Triraphis mollis (Purple Plumegrass) HCN stud rams tropical, temperate
*Urochloa panicoides (Liverseed Grass) nitrates cattle tropical, warm-temperate
*Urochloa mosambicensis (Sabi Grass) oxalates potentially toxic to horses; no published reports tropical, warm-temperate
*Zea mays (Maize) nitrates in lower parts of culm cattle warm-temperate
(Main sources Hurst, 1942; Gardner & Bennetts, 1956; Everist, 1981)
Grass Tetany
A condition known as grass tetany, grass staggers or hypomagnesaemia occurs most frequently in cattle, sometimes in sheep and possibly in horses. In Australia, the condition occurs commonly in southern New South Wales and north-eastern Victoria during winter grazing. It is not consistently associated with any grass species, and appears not to be caused by any specific plant toxin. In other countries, it is recorded in livestock grazing lush grass pastures and/or forage crops especially in temperate regions. The condition is associated with an imbalance in the components of blood serum especially with reduced magnesium levels. Symptoms include incoordination, muscular twitching, salivation, staggering, followed by convulsions and death usually in 6-10 hours.(From Everist, 1981.)
Physically Harmful Grasses
The spikelets of many grass species with stiff bristle-like awns and/or pungent calli can be injurious to domestic stock especially sheep and lambs. The spear-like awns and calli readily adhere to wool and hides, and penetrate the skin, eyes and mouth. The most common of these grasses are species of Aristida, Austrostipa (Stipa), Heteropogon, Hordeum and Perotis. Other harmful grasses include species of Cenchrus (Carolin & Clarke, 1991), which produce hard spiny burrs of fruit at maturity.
These grasses can cause discomfort, loss of weight, retardation of growth and death by starvation or thirst due to serious injury to eyes, nostrils, gums, skin and viscera. They also reduce the value of fleeces by occurring as vegetable faults in wool. The seeds of spear grasses (e.g. Aristida, Heteropogon, Hordeum, Sorghum s. lat.) also cause discomfort to humans and can be a serious problem in the management of national parks and other recreational areas catering for tourists. Partly due to its short 'seed-drop' period, Austrostipa is less of a problem in these areas. Similarly, the rigid pungent-pointed blades of Triodia species can penetrate the skin of humans and livestock, and can be troublesome in recreational areas. Triodia longiceps, probably the largest and hardest species in the genus, develops hummocks up to 2.4 m high and up to 6 m across, which are impenetrable to stock and can impede their movement and mustering.
Ethnobotanical Uses of Grasses
In the past, the indigenous traditionally nomadic Aborigines of Australia depended entirely on natural resources for all their survival needs. These resources included a large number of species of trees, shrubs and herbs, of which all or many parts of the plant were utilised in different ways to produce a wide range of products. Grasses constituted a significant component of useful plants. The seeds of many species of Brachiaria, Dactyloctenium (Button Grass), Echinochloa, Oryza, Paspalidium, Sporobolus and Yakirra, and those of Panicum decompositum (Native Millet) and Walwhalleya proluta (Rigid Panic), were ground with water into a paste and baked into dampers or seed cakes. The rhizomes and culms of Mnesithea were also eaten or chewed. The leaves, culms and roots of Cymbopogon, Chrysopogon (Ribbon Grass) and Triodia spp. were pulverised, boiled in water or mixed with animal fat, and applied as a wash to treat skin sores, coughs, colds, congestion, headaches, infected eyes and as a skin hardener for children. The resin or wax of Triodia spp. was heated, softened, and used as an adhesive for fixing heads to spears and woomeras, repairing coolamons, and in the making of tools, implements and artefacts. Smoke from the burning foliage of Triodia acted as a mosquito repellent, while Eulalia burnt with ant-bed produced an aromatic and medicinal smoke for infants. The culms of Heteropogon were split into strips, soaked and woven into armlets, anklets and baskets, and Eragrostis eriopoda (Woollybutt) and Cymbopogon bombycinus (Silky Oilgrass) were used in initiation and other ceremonies.
The bamboo, Bambusa arnhemica, is used to make spear shafts and didjeridus and is traded widely across the Arnhem Land Plateau.
For general references see Specht (1958), O'Connell et al. (1983), Smith & Wightman (1990), and Wightman et al. (1991, 1992a, b).
Ornamental Grasses
In relatively recent years, a large number of Australian native plants have been cultivated for the horticultural trade, and many have replaced exotics as domestic garden and nursery ornamentals. Others have become popular overseas and have earned valuable export income. Capillipedium parviflorum (Scentedtop) and C. spicigerum (Scentedtop) have aromatic decorative inflorescences and, together with Themeda triandra and species of Cymbopogon, are among the few native species grown as ornamentals and landscape plants. Australian ornamental grasses are predominantly deliberate or accidental introductions, some of which have become naturalised. They include species of Arundinaria, Arundo, Cortaderia (Pampas Grass), Ehrharta (Veldtgrass), Glyceria (Sweet Reed), Lagurus (Hare's-tail), Lamarckia (Golden-top), Melinis (Molasses Grass), Miscanthus (Eulalia), Pennisetum, Phalaris, Phyllostachys (Bamboo) and Setaria. Unfortunately, a significant number of these introduced ornamentals escape and establish as weeds. Arundo, Cortaderia, Pennisetum and Phyllostachys are among the most serious, and are declared noxious in some States.
Honey and Pollen Grasses
A few grasses are beneficial to bees, but none is of any value for nectar. Sorghum spp. s. lat. and Zea mays produce abundant pollen which is gathered by bees in large quantities. Cynodon dactylon produces pollen which attracts bees, but the contribution to apiculture is minimal.
Grain Sorghum (Sorghum bicolor) is particularly attractive to bees, and they will fly long distances to gather its pollen. This crop is rated medium in importance as a source of pollen.
The flowers of sweet or saccharine sorghums produce a pale yellow pollen, which is gathered by bees, but is of minor importance as a source of pollen.
Zea mays produces a pale yellow pollen in large quantities, which is worked by bees. It is of medium importance as a source of pollen.
For a general reference see Clemson (1985).
Miscellaneous Uses
For a general reference see Bor (1960).
Essential Oils
Species of Cymbopogon, Chrysopogon (syn. Vetiveria) (Vetiver) and other genera produce aromatic oils which are stored in the leaves, sheaths and/or roots and can be obtained by steam distillation. The oils are often pleasantly aromatic and are consequently valued in the perfumery trade. Species of commercial importance include Cymbopogon nardus and C. winterianus as a source of Citronella Oil, C. martinii for Palmarosa Oil, C. flexuosus for Lemon Grass Oil and Chrysopogon zizanioides for Vetiveria Oil.
The essential oils in grasses are also used in traditional medicines, the flavouring of food, and the scenting of cosmetics, soaps, disinfectants and polishes.
Paper Pulp
A large number of robust grasses produce very large quantities of cellulose in their bulk, which yield excellent material for paper pulp. Species utilised for this purpose belong chiefly to Arundo, Phragmites and Themeda, while the pulp derived from Imperata (Blady Grass) is lower in quality and suitable only in mixtures. The fibrous material remaining after the sugar has been extracted from the canes of Saccharum officinarum (Sugarcane) is used widely in the manufacture of inferior grades of paper, cardboard, and lining and insulation boards in the building industry. Studies on the cultivation of Cenchrus purpureus (Elephant Grass) as an agro-industrial crop in wet coastal areas of North Queensland have found it to be a potentially productive source of short fibres for pulping (Ferraris, 1978). Cereal grains and Sugarcane are important sources of industrial starch used in the paper and plastics industries (Wheeler et al., 1982).
Thatching
Broad-leaved and reed-like species of Arundo, Imperata, Phragmites, Bambusa, Saccharum, Themeda, and Chrysopogon are used in many countries for thatching, walling, house construction and the weaving of coarse mats for flooring. In Australia, some of these species, including the endemic bamboo, Bambusa arnhemica, are used in outback settlements as windbreaks, garden fences, stakes and for the insulation and walling of shade houses and small outbuildings.
Medicine
Although few grasses appear to have important pharmaceutal value, many species are used in traditional medicines by Australian Aborigines and other indigenous peoples. The oil-bearing species of Cymbopogon and Chrysopogon, including Cymbopogon nardus, Cymbopogon citratus and Chrysopogon zizanioides, are among the most widely used in developing countries for a variety of ailments. In addition, Panicum antidotale (Blue Panic), Phragmites karka (Tropical Reed), Saccharum officinarum, Setaria italica (Foxtail Millet) and Triticum aestivum are common medicinal species. The grain, culms or roots are used as infusions or ingredients in medicines, tonics or disinfectants for the treatment of fever, dysentery, anaemia, bowel complaints and other illnesses.
Grasses Causing Human Ailments
Many grasses are prolific producers of pollen, and, in certain environments and seasons, can cause hay fever or severe related conditions such as allergies and respiratory problems. For a general reference see Gardner & Bennetts (1956).
Grasses causing hay fever include Agrostis gigantea (Redtop Bent), Alopecurus pratensis (Meadow Foxtail), Anthoxanthum odoratum (Sweet Vernal), Avena barbata (Bearded Oats), A. fatua (Wild Oats), A. sativa (Oats), Bromus diandrus (Great Brome), Hordeum murinum (Barley Grass), Cynodon dactylon (Couch), Dactylis glomerata (Cocksfoot), Digitaria sanguinalis (Crabgrass), Festuca elatior (Tall Fescue), F. rubra (Red Fescue), Holcus lanatus (Yorkshire Fog), Lolium multiflorum (Italian Rye), L. perenne (Perennial Rye), L. temulentum (Darnel or Drake), Paspalum dilatatum (Paspalum), P. urvillei, Phleum pratense (Timothy), Poa annua (Annual Poa), P. pratensis (Kentucky Bluegrass), Secale cereale (Rye), Sorghum halepense (Johnson Grass), Triticum aestivum (Wheat) and Zea mays (Maize). With the exception of Cynodon, these grasses are introduced and have economic importance as cereals, weeds, cover or toxic grasses.
The native Chloris truncata (Windmill Grass) is suspected of causing dermatitis in humans and photosensitisation in lambs, but is also a useful rehabilitation grass.
Conclusion
Compared with other flowering plant groups on a global basis, this family is exceptional in relation to floristic composition, geographic distribution, biodiversity, ecological adaptability and human and wildlife economics.
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