Index of Species Information
SPECIES: Lolium multiflorum
SPECIES: Lolium multiflorum
AUTHORSHIP AND CITATION :
Carey, Jennifer H. 1995. Lolium multiflorum. In: Fire Effects Information System, [Online].
U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station,
Fire Sciences Laboratory (Producer). Available:
Lolium perenne subsp. multiflorum (Lam.) Husnot 
Lolium perenne var. aristatum Willd. [20,21]
SCS PLANT CODE :
COMMON NAMES :
The currently accepted scientific name for Italian ryegrass is Lolium
multiflorum Lam. (Poaceae) [31,33,59].
Some authors consider Italian ryegrass to be a variety or subspecies of
perennial ryegrass (L. perenne) [20,21,61,64]. However, Terrell ,
who wrote the monograph for the Lolium genus in 1968, provisionally
considered them separate species and listed the primary distinguishing
characteristics. Recent genetic work indicates that they are distinct
species, both possibly originating from a common ancestor, Wimmera
ryegrass (L. rigidum) [8,41]. The divergence of Italian ryegrass from
Wimmera ryegrass is hypothesized to have occurred fairly recently,
perhaps 6,000 years ago . Natural hybrids of Italian ryegrass and
perennial ryegrass are interfertile [8,41]. Natural and artificial
interspecific and intergeneric crosses are discussed .
LIFE FORM :
FEDERAL LEGAL STATUS :
No special status
OTHER STATUS :
DISTRIBUTION AND OCCURRENCE
SPECIES: Lolium multiflorum
GENERAL DISTRIBUTION :
Italian ryegrass, native to Europe, has been introduced throughout the
temperate regions of the world as an agricultural species. Records of
its cultivation in Italy date back to the thirteenth and fourteenth
centuries . Italian ryegrass occurs throughout the United States,
including Alaska and Hawaii, and in adjacent Canadian provinces
[20,31,35]. Because of difficulties in distinguishing Italian ryegrass
from perennial ryegrass, the exact northern distribution of Italian
ryegrass is not well documented.
Italian ryegrass probably occurs in most ecosystems.
AL AK AZ AR CA CO CT DE FL GA
HI ID IL IN IA KS KY LA ME MD
MA MI MN MS MO MT NE NV NH NJ
NM NY NC ND OH OK OR PA RI SC
SD TN TX UT VT VA WA WV WI WY
AB BC MB NB NF NS ON PE PQ SK
BLM PHYSIOGRAPHIC REGIONS :
1 Northern Pacific Border
2 Cascade Mountains
3 Southern Pacific Border
4 Sierra Mountains
5 Columbia Plateau
6 Upper Basin and Range
7 Lower Basin and Range
8 Northern Rocky Mountains
9 Middle Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains
15 Black Hills Uplift
16 Upper Missouri Basin and Broken Lands
KUCHLER PLANT ASSOCIATIONS :
SAF COVER TYPES :
243 Sierra Nevada mixed conifer
245 Pacific ponderosa pine
250 Blue oak-foothills pine
255 California coast live oak
SRM (RANGELAND) COVER TYPES :
201 Blue oak woodland
202 Coast live oak woodland
206 Chamise chaparral
208 Ceanothus mixed chaparral
214 Coastal prairie
215 Valley grassland
605 Sandsage prairie
611 Blue grama-buffalograss
Italian ryegrass may occur in other SRM cover types as well.
HABITAT TYPES AND PLANT COMMUNITIES :
Italian ryegrass occurs in grassland communities. It is a component of
the California annual grasslands, a community composed of exotic grass
species [6,28]. It occurs in a serpentine bunchgrass community, a
freshwater seep community, and a non-native grassland community in Ring
Mountain Preserve in California .
SPECIES: Lolium multiflorum
IMPORTANCE TO LIVESTOCK AND WILDLIFE :
Italian ryegrass is an important forage crop for livestock .
Meadow mice and white-tailed deer graze Italian ryegrass [38,47].
Italian ryegrass is palatable to livestock .
NUTRITIONAL VALUE :
Italian ryegrass is highly nutritious . Fresh, early bloom, aerial
portions of Italian ryegrass average 8.1 percent ash, 30.1 percent crude
fiber, 5.8 percent protein, 55.2 nitrogen-free extract, and 0.8 percent
ether extract (dry weight). Nutritional values for other Italian
ryegrass growth stages and for hay are reported . The influence of
shading, sward density, and nitrogen fertilizer on Italian ryegrass
nutritive value is reported .
COVER VALUE :
Italian ryegrass is considered poor cover for small mammals and
waterfowl in Montana .
Pocket gophers increase in areas seeded with Italian ryegrass, possibly
because of increased cover .
VALUE FOR REHABILITATION OF DISTURBED SITES :
Italian ryegrass is a quick, effective groundcover for erosion control
and as a winter cover crop . It is often used for temporary erosion
control; it does not generally persist in cold ecosystems such as in
Alaska, nor does it tend to spread into adjacent undisturbed areas .
It has a lower pH limit of 4.5. Seeding rates are described .
Seeding of Italian ryegrass is often followed by seeding with perennial
species the following year. If seeded together, Italian ryegrass often
outcompetes the perennials [25,63].
Although Italian ryegrass is one of the most commonly used grasses for
revegetating burned sites, its use is controversial. Discussion of this
controversy is in FIRE MANAGEMENT.
OTHER USES AND VALUES :
Italian ryegrass is used as turf grass in the southern United States .
OTHER MANAGEMENT CONSIDERATIONS :
Italian ryegrass is grown for winter pasture, hay, and silage. In the
United States it is cultivated primarily on the Atlantic Coast, in
southern humid areas, and on the Pacific Coast west of the Cascade Range
and Sierra Nevada. There are over 150 recognized cultivars of Italian
and perennial ryegrasses. Planting and harvesting methods are discussed
. Nitrogen, phosphorus, and calcium are required for high quality
Italian ryegrass production .
Italian ryegrass is a serious weed in cereal crops and grass seed crops
[51,54]. In western Oregon, where most of the Italian ryegrass seed is
produced, seed remains dormant in the cold, wet soil during winter and
then volunteers in crops when fields are plowed. Diclofop has been an
effective herbicide, but Italian ryegrass is gaining resistance to it
. Italian ryegrass cultivars have also developed a tolerance of the
herbicide fenoxaprop .
BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Lolium multiflorum
GENERAL BOTANICAL CHARACTERISTICS :
Italian ryegrass is an introduced, annual or biennial, cool-season
bunchgrass. The erect, spreading, or decumbent culms grow 50 inches
(127 cm) tall. Spikelets are 11- to 22-flowered; lemmas are usually
awned . Roots are shallow when irrigated, which has led to the
assumption that Italian ryegrass has a shallow root system. However,
the fine, fibrous root system extends over 3 feet (1 m) deep on
nonirrigated sites [7,52,55].
RAUNKIAER LIFE FORM :
REGENERATION PROCESSES :
Italian ryegrass regenerates by seed. It is self-incompatible .
Seeds are probably dispersed by animals. Two cultivars (`Tribune' and
`Lemtal') had higher germination rates 6 months after harvest (95
percent) than 3 weeks after harvest (50 percent), indicating some degree
of dormancy immediately after harvest . Seeds germinate rapidly
without pretreatment . Germination rates are high; 2-week
germination was 80 percent under summer day/night temperatures (86/62
degrees Fahrenheit [30/17 deg C]), 76 percent under spring and fall
temperatures (74/50 degrees Fahrenheit [23/10 deg C]), and 71 percent
under winter temperatures (62/39 degrees Fahrenheit [17/4 deg C]) .
Italian ryegrass is unlikely to form a substantial seedbank because
seeds germinate readily . Thompson and Grime  place Italian
ryegrass in the transient seedbank category; seeds are present only for
a short time in the summer and fall. Where high soil temperatures are
associated with intermediate soil moisture, viable seed is depleted
through germination . However, seed dormancy is induced when seeds
are buried in cold, wet soil. Dormancy in buried seed did not reach
maximum levels until 120 days after burial . The longevity of
buried Italian ryegrass seed is not known.
Italian ryegrass tillers profusely [7,29].
SITE CHARACTERISTICS :
Italian ryegrass grows in a wide range of soil types except for
excessively drained or very poorly drained soils . It requires
medium to high soil fertility in order to persist on a site .
Italian ryegrass is intolerant of hot, dry weather. It can survive
short periods of flooding if well established .
Italian ryegrass is reported to grow at less than 3,280 (1,000 m) in
California , at 6,400 feet (1,350 m) in Utah, 6,500 feet (1,380 m)
in Montana, and 4,000 to 8,000 feet (1,220-2,440) in Colorado .
SUCCESSIONAL STATUS :
Italian ryegrass is a shade intolerant species. In a reciprocal
transplant study between the California annual grasslands and an
adjacent coast live oak (Quercus agrifolia) woodland, Italian ryegrass
disappeared after 1 year of shading by the oak canopy. The canopy did
not inhibit germination, but seedling survival was poor. Italian
ryegrass was the most shade-sensitive herbaceous species in the study
. Italian ryegrass generally increased in cover with removal of
blue oak (Q. douglasii) in woodlands and savannahs in the northern
Sierra Nevada foothills .
In portions of the California annual grasslands, three species
frequently coexist: wild oat (Avena fatua), soft chess (Bromus
hordeaceus), and Italian ryegrass. Wild oat retains dominance but is
unable to exclude the other two species. Italian ryegrass has the
smallest seeds but overcomes this disadvantage with rapid growth .
In the Pampean grasslands of Argentina, postagricultural succession was
observed for 5 years. Italian ryegrass was not present the first year
and was not planted, but occurred the second year with 5.6 percent cover
and increased to 42.8 percent cover by the fifth year. As Italian
ryegrass became more homogeneously distributed, plant diversity
decreased. The thick litter of Italian ryegrass may have inhibited
other species .
In some ecosystems, Italian ryegrass is succeeded by perennial
herbaceous species and shrubs. Italian ryegrass was initially prominent
where introduced onto sites disturbed by the 1980 eruption of Mount St.
Helens. However, the native, perennial colonizers fireweed (Epilobium
angustifolium) and western pearlyeverlasting (Anaphalis margaritacea)
soon became dominant .
Coyotebrush (Baccharis pilularis) invades California annual grasslands
if grazing ceases and suppresses Italian ryegrass [34,43]. In May in
the Santa Cruz Mountains, open grasslands contained 340 grams per square
meter Italian ryegrass, but 2- to 3-year-old coyotebrush stands
contained only 2 grams per square meter, and 9-year-old coyotebrush
stands contained no Italian ryegrass .
SEASONAL DEVELOPMENT :
In California, Italian ryegrass germinates with the onset of the fall
rainy season , generally when temperatures dip below 50 degrees
Fahrenheit (10 deg C) . Growth is initially rapid, slows in the
winter, then increases again in the spring [7,24]. Spring growth does
not occur until the mean daily temperature rises above 50 degrees
Fahrenheit (10 deg C) for several days, usually in late February in
southern California. No growth occurs until March above 2,500 feet (760
Although aboveground growth slows in the winter, Italian ryegrass roots
continue to grow. In mid-January in California, roots averaged 8 inches
(20 cm) deep, and in early March roots averaged 12 inches (30 cm) deep
while seedlings were still in the two- to three-tiller stage. By
mid-April, roots were 23 inches (58 cm) deep and most tillers had been
produced. Italian ryegrass roots excavated in July were 56 inches (142
cm) deep .
Italian ryegrass begins drying in late April in California . In
1960 near Berkeley, maximum Italian ryegrass biomass occurred in late
In Colorado, anthesis begins in June and ends in July. In Montana, it
begins in May and ends in July .
SPECIES: Lolium multiflorum
FIRE ECOLOGY OR ADAPTATIONS :
Natural fires in Italian ryegrass stands are most likely to occur during
the dry season when Italian ryegrass has already produced seed and dried
out. Dense stands of dry Italian ryegrass burn readily [23,45].
FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find Fire Regimes".
POSTFIRE REGENERATION STRATEGY :
Ground residual colonizer (on-site, initial community)
SPECIES: Lolium multiflorum
IMMEDIATE FIRE EFFECT ON PLANT :
Fire probably kills Italian ryegrass. Seeds may survive fire.
DISCUSSION AND QUALIFICATION OF FIRE EFFECT :
PLANT RESPONSE TO FIRE :
Italian ryegrass generally decreases after fire. A California annual
grassland site on the coastal foothills near Berkeley burned in July.
Forbs generally increased and grasses decreased in the first growing
season after the fire. Burned sites produced lower Italian ryegrass
yields than unburned sites. Italian ryegrass height was significantly
lower the year after the fire on burned sites than unburned sites :
Average Height (Inches)
Dec 1 Feb 20 May 1
Burned 2.4 3.5 13.7
Unburned 3.7 6.9 16.1
A March 5 fire on a Georgia old field resulted in a significant (P<0.05)
decrease in Italian ryegrass yield. The control produced 98.4 grams per
square meter and the burned area produced 47.4 grams per square meter in
the summer following the fire .
Italian ryegrass was present (0.1% cover) after a July fire in San
Bernardino County, California. The prefire community, dominated by
brittle bush (Encelia farinosa), had not burned for 21 years and did not
contain Italian ryegrass . The seed source for the postfire
population of Italian ryegrass was not described.
DISCUSSION AND QUALIFICATION OF PLANT RESPONSE :
FIRE MANAGEMENT CONSIDERATIONS :
For years Italian ryegrass has been the most commonly used species for
controlling erosion on burned chaparral sites, especially in northern
California and coastal areas. Seed is usually broadcast aerially in the
fall following the fire but preceding the winter rains. Italian
ryegrass has reliable germination, rapid early growth, a short life
span, abundant fibrous roots, inexpensive seed, and broad site
adaptability . However, the wisdom of ryegrass seeding has been
questioned for decades, and recent literature indicates that postfire
seeding of Italian ryegrass may cause more harm than good. The purpose
of the seeding is to control erosion which is often severe during winter
rains on steep slopes in California. However, studies have shown that
the seeding is not effective at controlling erosion the first year and
may even increase erosion in succeeding years. In addition, Italian
ryegrass outcompetes the recovering native vegetation and may increase
the fire hazard. The controversy is reviewed by Barro and Conard 
and Gautier , and is summarized here.
Several studies have shown that erosion was not controlled, and even
increased, with Italian ryegrass seeding [23,57]. Erosion was greater
on seeded sites than on unseeded sites of the 1985 Las Pilitas Fire in
the Santa Lucia Range, Monterey County, California. Researchers found
that pocket gopher activity was greater on seeded sites and was the
cause of the increased erosion . Nadkarni and Odion  suggest
that as Italian ryegrass declines, vegetative cover on seeded sites may
actually be less than cover on unseeded sites, and thus erosion may be
greater. After the Marble-Cone Fire in the Santa Lucia Range, heavy
rains in January washed 1.2 to 3.1 inches (3-8 cm) of surface soil from
slopes greater than 20 percent. The erosion occurred before seeded
Italian ryegrass had formed an effective cover . Winter rains are
often not sufficient for Italian ryegrass germination until December or
January when the daily temperature is too cool for adequate growth. A
wetting agent applied to the soil surface during the seeding may
encourage earlier germination .
Seeding Italian ryegrass may have long-term detrimental effects on
chaparral communities because Italian ryegrass interferes with native
species regeneration. On sites seeded with Italian ryegrass, the
seedbank becomes depleted of fire-following species because they may
germinate but do not establish . After Italian ryegrass dies out it
often leaves behind a thinned out chaparral with considerably fewer
nonsprouting species such as wedgeleaf ceanothus (Ceanothus cuneatus)
than in areas without Italian ryegrass seeding . In seeded plots in
burned chaparral in the Santa Ynez Mountains, California, there was a 40
percent reduction in species diversity compared with unseeded plots.
The predominant native Amador rushrose (Helianthemum scoparium) was less
dense in the seeded treatment, and two other species usually found
(hoaryleaf ceanothus [C. crassifolius] and common turricula [Turricula
parryi]) were absent from the seeded plots. The fire-annual yellow
whisperingbells (Emmenanthe penduliflora) had over 50 percent less cover
on seeded plots than unseeded plots at one site in southern California
. The first year following the Las Pilitas Fire in the Santa Lucia
Mountains, Italian ryegrass interfered with the regeneration of lupine
(Lupinus spp.), lotus (Lotus spp.), and chamise (Adenostoma
fasciculatum) . One year after fire in chaparral in the Santa
Monica Mountains, California, Italian ryegrass cover was negatively
correlated with herbaceous species and with island ceanothus (Ceanothus
megacarpus) . Because of the ability of Italian ryegrass to compete
well with woody species, it is recommended for seeding of fire breaks
within chaparral communities .
Italian ryegrass restricts tree regeneration where seeded on burned
forested sites. Italian ryegrass interfered with the regeneration of
sugar pine (Pinus lambertiana) and Coulter pine (P. coulteri) seedlings
after the Marble-Cone Fire . Two years after fire on the Stanislaus
National Forest, California, postfire regeneration of ponderosa pine (P.
ponderosa) was absent where Italian ryegrass cover was greater than 40
An additional detrimental effect of postfire seeding is that dense
stands of Italian ryegrass burn readily, and early recurring fire is
destructive to regenerating shrubs . The natural fire interval in
chaparral is about 10 to 100 years . An August 1979 fire on Otay
Mountain, San Diego County, California, was seeded with Italian
ryegrass. The year had near-record precipitation so Italian ryegrass
growth was exceptional. In July another fire occurred in the areas
seeded with Italian ryegrass. This second fire killed nearly all
seedlings of explorer's bush (C. oliganthus), and chamise was reduced by
up to 97 percent. Mission manzanita (Xylococcus bicolor), a postfire
sprouter, suffered substantial mortality. It is believed that such an
early return fire causes drastic shifts in species composition .
In the Santa Ynez Mountains a July fire burned into seeded areas but not
unseeded areas 2 years after the original fire .
After fire in grasslands containing Italian ryegrass, grazing should be
delayed or reduced to allow Italian ryegrass to recover .
SPECIES: Lolium multiflorum
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