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Bromus inermis Leyss.

Syn.: Zerna inermis (Leyss.) Lindm.
Bromus glabrescens Honda
Bromus tatewakii Honda
Smooth bromegrass

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 unpublished.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


One of the best hay and pasture grasses, grown extensively in United States, Europe, Russia and Argentina. Often grown for long-term leys. Equal to any forage grass in areas where it is adapted because of high palatability and yield. Excellent for soil erosion because of the interlocking root system. Especially valuable in semi-arid regions, as the Prairie Provinces of Canada and the Great Plains of the United States. (Reed, 1976)

Folk Medicine

Tests for antibacterial activity against Mycobacterium tuberculosis have proved negative, and positive (Watt and Breyer-Brandwijk, 1962).


On a zero-moisture basis, smooth brome (moisture content 4.2 to 16.8%, mean of 215 cases = 10.3) contains 3.0 to 27.9 g crude protein (mean of 245 cases = 12.3), 1.2 to 6.8 g fat (mean of 238 cases = 2.6), 16.3 to 46.0 g crude fiber (mean of 240 cases = 31.7), 4.6 to 12.4 g ash (mean of 244 cases = 8.8), and 34.1 to 52.2 g N-free extract (mean of 245 cases = 44.6), 210 to 980 mg Ca (mean of 125 cases = 430), 40 to 740 mg P (mean of 126 cases = 280), 2.8 to 10.1 mg Cu mean of 32 cases = 5.2), 1470 to 3500 mg K (mean of 104 cases 2360), 80 to 420 mg Mg (mean of 103 cases = 210), 4 to 34 mg Fe (mean of 88 cases = 10), 16.0 to 21.3 mg niacin (mean of 7 cases = 18.6), 167 to 332 mg choline (mean of 5 cases 251), and 1.0 to 84.0 mg carotene (mean of 26 cases 16.7) (Miller, 1958).


The species may become ergotized with Claviceps, hence becoming very dangerous.


Long-lived, sod-forming perennial, spreading by creeping rhizomes, leafy; culms erect, 60–120 cm tall, glabrous; basal and stem leaves numerous; leaf-blades usually 10–15 cm long, sometimes up to 55 cm long, 3–8 mm broad, or up to 1.3 cm broad, nearly flat, somewhat firm; ligules less than 2 mm long, truncate; panicles narrow, the erect branches ascending or spreading in flower, 10–20 cm long, rather dense, branches subverticillate, short; spikelets 2.5 cm long, narrowly oblong, pale green to slightly purple-tinged, 6–8-flowered; lemmas mucronate or short-awned, narrowly oblong, about 10 mm long, membranous, obtuse, with 2 minute teeth, the awn wanting or to 1 mm long between the teeth; glumes acute, the lower 4–5 mm long, the upper 6–7 mm long; anthers linear, orange-yellow, 4–5 mm long. Seed 299,880 to 300,000/kg.


About 34 cvs are classified as northern and southern. The Northern strains, derived from Siberian introductions, adapted to conditions in adjacent Canada and the northern Plains of United States include: 'Mancharl, 'Parkland', 'Martin', 'Canadian Certified', 'Wiley', 'Chapple No. 14', and 'Mandon 404'; these bunch more than southern strains, do not become sod-bound so rapidly, and are less productive in southern areas. Southern strains, derived from Hungarian introductions, adapted to cornbelt areas of Central United States and as far north as southern Minnesota, include: 'Lincoln', 'Fisher', 'Achenbach', and 'Elberry'; these are not winter-hardy in northern areas. 'Prior', developed in Sweden for permanent pastures or long leys on dry soils; in Germany, 'Von Kanekes', for light soils, 'N.F.G.' for moister, clayey soils. The genus Bromus contains many complex, polyploid series. Bromus inermis belongs to section Bromopsis, containing wild species with chromosome numbers ranging from 2x to 8x. Following its introduction to North America, smooth broome, an aggressive species, has tended to replace native American species of sect. Bromopsis, especially B. pumpellianus. Hybridization studies have been made between: B. inermis, 8x; B. pumpellianus, 8x; and material of the introduced B. erectus complex (6x, 8x, 10x, though the last is probably itself hybrid). An objective of these studies was to incorporate into inermis the larger seeds of pumpellianus and better seedling vigous of erectus. The three species are related, crossable and give quite fertile hybrids. Collections of B. inermis in North America show varying meiotic irregularity and aneuploidy. This is probably a result of introgression from B. pumpellianus and the B. erectus complex. Quite a high degree of meiotic irregularity may be tolerated under natural conditions in a long lived, cross- pollinated species such as B. inermis, which can spread aggressively by rhizomes (Borrill, 1976). Reported from the Eurosiberian Center of Diversity, smooth bromegrass or cvs thereof is reported to tolerate alkali, disease, drought, frost, fungi, grazing, heavy soil, high pH, mycobacteria, salt, viruses, and weeds. (2n = 28, 42, 56) (Duke, 1978).


Native to Central and Northern Europe and temperate Asia, extending to China. Introduced to United States and Canada in 1880 from Hungary and in 1896 from Russia. Now widely distributed to Argentina and elsewhere.


Best adapted to regions with moderate rainfall and moderate cool summer temperatures. Suited to silt or clay soils, deep loams, but also does well on light sandy soils, on well-drained soils. Less drought resistant than crested wheatgrass, but does not tolerate temperature extremes. Also suited for irrigated areas. Not recommended for saline or alkali soils. Ranging from Boreal Moist to Rain through Subtropical Dry Forest Life Zones, smooth brome is reported to tolerate annual precipitation of 3.2 to 17.6 dm (mean of 46 cases = 7.2), annual temperature of 4.3 to 19.9°C (mean of 46 cases = 8.8), and pH of 4.9 to 8.2 (mean of 40 cases = 6.4) (Duke, 1978, 1979).


Propagated from seed. Seedbed should be firm and seed should not be covered to more than 6–13 mm depth. When grown for hay, seed 11–16 kg/ha with 4–7 kg/ha alfalfa; for pasture, 1–1.5 kg/ha of Ladino or White Dutch clover should be seeded with the bromegrass and the alfalfa. When grown for seed in irrigated areas, smooth bromegrass is planted in rows 75–100 cm apart and seeded at 3.3 kg/ha. This grass rapidly becomes sod-bound if sown pure, and is nearly always sown in mixtures with alfalfa, sweet clover, red clover or Lotus corniculatus. Growth starts early in spring with a further period of growth in early autumn under favorable moisture conditions. Prior to planting, broadcast and plow down up to 220 kg/ha of P2O5 based on soil needs. At planting apply 55 kg/ha of nitrogen plus up to 55 kg/ha phosphate, based on soil needs. Established stands of bromegrass for hay or pasture should be fertilized with 55 to 110 kg/ha of nitrogen in early spring and another 55 to 110 kg/ha at midseason. For seed production, 83 to 110 kg/ha of nitrogen should be applied in September and again in the spring. Nitrogen fertilization is required for optimum hay, pasture or seed yields in most areas. Plants spread rapidly from rhizomes.


Bromegrass is long-lived if irrigated, fertilized and harvested properly. It provides palatable pasture and hay if not too mature. It resists over-grazing and trampling, but will not persist under close grazing. It should be managed so that 15–20 cm of grass are always left on pasture. Old, unproductive, sod-bound swards may be improved by heavy disking and overseeding with a legume or by applying nitrogenous fertilizer in spring. In some areas, such as Kansas, it becomes sod-bound just a few years after planting. This condition can be corrected by applying sufficient nitrogen each year and grazing it moderately. Properly managed stands can be maintained almost indefinitely.

Yields and Economics

Smooth bromegrass is said to produce consistently about 12.5 T/ha (Reed, 1976). Pasture trails with this grass have shown that about 1.5 T/ha of beef can be obtained. Seeds mature in late summer when plants are 93–123 cm tall. Seed yields of 1.5 T/ha are obtained when irrigated. Knowles et al, (1978) however, report yields closer to 2.5 MT with 2 cuts 'Carlton' per year at Saskatoon, 8.5 MT with 4 cuts. At Lacombe, Canada, with 506 cuts per year, 'Carlton' and 'Manchar' yielded ca 17 MT, 'Magna' closer to 18. This is the most widely utilized of the cultivated bromegrasses, being both highly palatable and nutritious in regions of adaptability. Used for hay, pasture and ensilage in northern states east to North Dakota, in Pacific Northwest and in Intermontane area of West; as a meadow grass in northeastern United States; as important hay grass in Hungary, Ukraine and temperate Asia, and for long-term leys in western Argentina.


According to the phytomass files (Duke, 1981b), annual productivity ranges from 1 to 11 MT/ha (1–3 in Canada, 2 in Egypt, 2–11 in USSR). Hay yields of 12.5 MT/ha are reported (Duke, 1978). Bromus tectorum DM yields range from ca 1–8 MT/ha, B. unioloides gives 8 in Australia, 4–16 in France, 13 in Jamaica, 13–14 in Poland, 6–7 in the US (Duke, 1981b).

Biotic Factors

Following fungi have been reported on smooth bromegrass: Alternaria tenuis, Ascochyta graminicola var. diedickeana and var. holci, A. sorghi, Cercospora festucae, Cercosporella herpotrichoides, Claviceps purpurea, Colletotrichum graminicola, Curvularia geniculata, Epichloe typhina, Erysiphe graminis, Fusarium acuminatum, F. culmorum, F. equiseti, F. graminearum, F. oxysporum, F. scirpi, F. poae, F. solani, Gloesporium bolleyi, Helminthosporium bromi, H. leersii, H. sativum, H. giganteum, H. sorokinianum, Ophiobolus graminis, Ovularia pulchella var. agropyri, 0. pusilla, Pellicularia filamentosa, Pyrenochaeta terrestris, Pyrenophora bromi, Phyllachora graminis Puccinia bromina, P. coronifera, P. coronata, P. dispersa, P. graminis, P. rubigo-vera, Pythium arrhenomanes var. canadense, P. debaryanum, P. graminicola, P. irregulare, P. ultimum, P. vexans, Rhizoctonia solani, Rhyncosporium secalis, Sclerophthora macrospora, Sclerotinia borealis, Septoria bromigena, S. bromi, S. affinis, Scolecotrichum graminis, Selenophoma bromigena, Stagonospora bromi, Thanate cucumeris, Trichometasphaeria taminensis, Urocystis bromi, Ustilago bromina, U. bromivora, U. bullata, U. macrospora, U. striiformis. Bacterial diseases are caused by the following agents: Pseudomonas coronafaciens var. atropurpurea and Xanthomonas translucens var. cerealis and var. undulosum. Virus diseases include: Brome mosaic and Marmor graminis virus. Nematodes isolated from Smooth bromegrass include: Ditylenchus dipsaci, Helicotylenchus pseudorobustus, Heterodera avenae, Meloidogyne arenaria, M. hapla, M. incognita acrita, M. javanica, Paratylenchus projectus, Pratylenchus penetrans, and P. pratensis (Golden, p.c., 1984). Bank's grass mite has been a problem when this grass is grown from seed in some parts of Nevada.


Complete list of references for Duke, Handbook of Energy Crops
Last update Tuesday, December 30, 1997