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| ## BulbOUS {#bulbous .Title-Header}                                   |
|                                                                       |
| ## bluegrass {#bluegrass .Title-Header}                               |
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| *Poa bulbosa* L.                                                      |
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| Plant Symbol = POBU                                                   |
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Contributed by: USDA NRCS Plant Materials Center, Pullman, Washington

![](media/image2.jpeg){width="2.936111111111111in"
height="4.020833333333333in"}

Dave Skinner, Pullman PMC

**Alternate Names**

##### Winter bluegrass {#winter-bluegrass .Header-3}

#####  {#section .Header-3}

##### Uses {#uses .Header-3}

##### *Cultural*: Bulbous bluegrass is currently considered to be a weedy species, but was used in the mid 1900\'s as a grass for turf, pasture and erosion control.  {#cultural-bulbous-bluegrass-is-currently-considered-to-be-a-weedy-species-but-was-used-in-the-mid-1900s-as-a-grass-for-turf-pasture-and-erosion-control. .Header-3}

#####  {#section-1 .Header-3}

##### *Grazing:* In early spring, when lush and green it is thought to be a desirable forage species. However, it matures quickly and does not provide a significant amount of forage for livestock. {#grazing-in-early-spring-when-lush-and-green-it-is-thought-to-be-a-desirable-forage-species.-however-it-matures-quickly-and-does-not-provide-a-significant-amount-of-forage-for-livestock. .Header-3}

#####  {#section-2 .Header-3}

##### *Wildlife:* The bulblets of bulbous bluegrass contain high levels of starch and fat, and therefore are attractive to rodents and birds (Locke & Burrill, 1994).  {#wildlife-the-bulblets-of-bulbous-bluegrass-contain-high-levels-of-starch-and-fat-and-therefore-are-attractive-to-rodents-and-birds-locke-burrill-1994. .Header-3}

##### Status {#status .Header-3}

Consult the PLANTS Web
([http://plants.usda.gov](http://plants.usda.gov/)) site and your State
Department of Natural Resources for this plant's current status (e.g.
threatened or endangered species, state noxious status, and wetland
indicator values).

**Weediness**

Bulbous bluegrass is often the first invading species on disturbed
shallow soils that are moist during the winter and early spring (Locke &
Burrill, 1994).

The grass is known to move from marginal sites to nearby fields of crop
and hay. It is easily controlled with early season cultivation using
implements such as a spiketooth harrow or viber shanks and herbicides
for grass control.

##### Description {#description .Header-3}

*General*: Grass Family (Poaceae). Bulbous bluegrass is an introduced,
short-lived perennial cool-season grass. It is the only grass known to
have true bulbs (Halperin, 1933). The bulbs are normally dormant from
mid-May through early October. When the weather begins to cool, leaves
emerge from the bulbs. Growth is slow during the winter months, and by
early March the plant is typically around 3 inches tall. As weather
becomes warmer, it grows to a height of 6 to 24 inches. Leaf blades are
narrow, flat or loosely rolled, with membranous ligules about 1/8 inch
long. Few culms are produced per plant. Flowers are usually modified to
bulblets with a dark purple base. The panicle has a plume-like
appearance from the long, slender lemma (some refer to them as bracts)
attached to each bulblet. The bulblets typically mature around early
May, and soon after the grass senesces. The bulblets produced within the
inflorescences germinate after a period of dormancy lasting a few months
up to 2 years.

The formation of bulblets in bulbous bluegrass is a type of apomictic
vivipary. The lowermost floret of the spikelet usually has a developed
lemma, but lacks a palea. The lemmas of the second and third florets are
long and leaf-like and are attached to a bulblet, which develops from
the floral parts (Gould & Shaw, 1983).

Bulbous bluegrass reproduces primarily through asexual means in North
America (USDA, 1948; Hitchcock, 1971; Gaines & Swan, 1972; Cronquist,
1977). However, it is believed to reproduce primarily through sexual
means in its native habitat of Europe and mid East Asia (Youngner &
McKell, 1972). This phenomenon may be explained by differences in
climate. Youngner (1960) conducted a study to determine the effects of
day length and temperature on reproductive structures of bulbous
bluegrass, and found high temperatures (70-80ºF) and long days (16 hrs.)
following inflorescence initiation promoted seed production, whereas
cool temperatures (68ºF or less) and short days (8 hrs.) promoted
bulblet production. Long days and cool temperatures or short days and
high temperatures produced panicles with both seeds and bulblets.

Sexual reproduction of bulbous bluegrass may occur more frequently in
North America than originally expected. Novak & Welfley (1997) used
bulbous bluegrass to evaluate genetic diversity within and among
populations of an introduced, vegetatively reproductive species, and
found the diversity to be surprisingly high at both the species and
population levels. They concluded the diversity likely resulted from a
combination of sexual reproduction, the autopolyploid nature of the
species, and multiple introduction events.

Bulbous bluegrass was introduced to North America accidentally, as a
contaminant of alfalfa and clover seed. The grass was also introduced
intentionally, for research purposes. In 1906 the USDA Office of Foreign
Plant Introduction received bulblets of bulbous bluegrass from Russia
(Vinall & Westover, 1928). The bulblets were grown by the Arlington, VA
Experimental Farm in 1907, 1908 and 1909, and at Pullman, WA in 1907. At
that time the grass was reported as having no particular promise, and
the investigations soon ended.

Bulbous bluegrass was re-evaluated in 1915 after the groundskeepers at
the state capitol in Richmond, VA asked the USDA for assistance
identifying the grass and determining methods to eradicate it. The
groundskeepers considered the grass to be undesirable since it performed
poorly in the summer months. The USDA grew the grass in a greenhouse and
determined the grass to be *Poa bulbosa.* They advised the
groundskeepers not to eradicate it, but instead manage it as winter
grass in combination with Bermuda grass for the summer months (Vinall &
Westover, 1928).

In 1916 bulblets of the grass were distributed by the USDA to several
experiment stations. Commercial production of the grass followed, and in
1928, Medford, OR was considered the center of production (Vinall &
Westover, 1928). During this time, bulbous bluegrass was used to
compliment Bermuda grass in pastures and turf, but new evaluations were
beginning to demonstrate the grass did not tolerate frequent clipping,
and actually outcompeted Bermuda grass when both were grown together.

Bulbous bluegrass was still thought to have value in 1948, when it was
recommended to replace cheatgrass on poor condition sites and as an
understory species in seed mixtures in southern Idaho (Hull & Stewart,
1948).

The Pullman Plant Materials Center (PMC) evaluated bulbous bluegrass for
use in critical area plantings in the 1950\'s. In 1956, P-4784 was
released but the bulblets failed to retain acceptable levels of
germination. Consequently, P-4784 was not distributed to growers.

As recently as 1997, the merits of bulbous bluegrass were still being
considered, when it was included in a study to determine optimal species
for low-input sustainable turf grass in the upper Midwest. The grass
performed poorly and was not recommended for this use (Diesburg, 1997).

*Distribution*: Bulbous bluegrass grows in nearly all temperate and
subtropical regions throughout the world. In North America, it inhabits
roadsides and hay and crop fields. It tends to be more common in western
states than eastern states.

**Adaptation**

Bulbous bluegrass is best adapted to areas that have dry summers, mild
winters, and winter rainfall. It is typically found within the 12\" --
40\" precipitation zones.

**Establishment**

This species is not recommended for seeding.

**Mechanical Control**

Spring tillage is very effective in controlling bulbous bluegrass. Fall
tillage is less effective. Haying and mowing are not effective because
the seed heads are frequently shorter than the cutting height. Burning
is not effective because it rarely reduces the number of bulblets in the
soil.

**Environmental/Cultural Control**

Infestations can be prevented by using crop seed, hay and straw that is
free of bulbous bluegrass bulblets or seed. In addition, cleaning
equipment before moving from a site infested with bulbous bluegrass and
controlling weeds along fence rows and roadsides will prevent its
spread.

Within crop fields where bulbous bluegrass has established, it can be
controlled by rotation with a spring crop or to permanent pasture or
alfalfa. In uncropped areas, bulbous bluegrass can be managed by
establishing a stand of competitive perennial grass.

Intensive spring grazing can reduce bulbous bluegrass populations
providing that intensive grazing is applied over a period of several
growing seasons. Consult with the NRCS or a Certified Rangeland
Management Specialist to determine if this practice could adversely
impact other grazing plants and/or soil conditions.

**Chemical Control**

There is a wide range of chemicals available to control bulbous
bluegrass. Contact your local agricultural extension agent or county
weed specialist to learn what products work best in your area and how to
use them properly. Always read and follow label and safety instructions.

##### Biological Control {#biological-control .Header-3}

##### No biological controls are known. {#no-biological-controls-are-known. .Header-3}

#####  {#section-3 .Header-3}

##### Cultivars, Improved and Selected Materials Including Area of Origin {#cultivars-improved-and-selected-materials-including-area-of-origin .Header-3}

The Pullman Plant Materials Center (PMC) evaluated bulbous bluegrass for
several years in the 1950\'s. P-4784, an ecotype collected near the
Washington-Idaho state line exhibited very robust late maturing growth.
It was released in 1956 in cooperation with the Idaho Agricultural
Experiment Station. The Pullman PMC grew P-4784 for several years but
the bulblets failed to retain acceptable levels of germination.
Consequently, P-4784 was not distributed to growers. All seed stock of
P-4784 was destroyed in 1976 based on its poor seed storage
characteristic and its weedy nature. Currently no seed is commercially
available.

##### Illustrations and Photographs {#illustrations-and-photographs .Header-3}

Burrill, L. C., et al. 1996. Weeds of the West, 5^th^ ed., T.D. Whitson,
editor. University of Wyoming. Larimie, WY. pp. 482-483.

Cronquist, A., A.H. Holmgren, N.H. Holmgren, J.L. Revcal, P.K. Holmgren.
1977. Intermountain Flora, vol. 6. Columbia University Press, New York.
p. 235.

Gaines, X.M. and D.G. Swan. 1972. Weeds of Eastern Washington and
Adjacent Areas. C.W. Hill, Spokane, WA. pp. 54-55.

**References**

Burrill, L. C., et al. 1996. Weeds of the West, 5^th^ ed., T.D. Whitson,
editor. University of Wyoming. Larimie, WY. pp. 482-483.

Cronquist, A., A.H. Holmgren, N.H. Holmgren, J.L. Revcal, P.K. Holmgren.
1977. Intermountain Flora, vol. 6. Columbia University Press, New York.
pp. 234-235.

Diesburg, K.L., et al. 1997. Species for low-input sustainable turf in
the U.S. upper Midwest. Agron. J. 89:690-694.

Gaines, X.M. and D.G. Swan. 1972. Weeds of Eastern Washington and
Adjacent Areas. C.W. Hill, Spokane, WA. pp. 54-55.

Gould, F.W. and R.B. Shaw. 1983. Grass Systematics, 2^nd^ ed. Texas A &
M University Press, College Station, TX. p. 82.

Halperin, M. 1933. The taxonomy and morphology of bulbous bluegrass,
*Poa bulbosa vivipara*. J. Am. Soc. Agron. 25:408-413.

Hitchcock, A.S. 1971. Manual of the Grasses of the United States, 2^nd^
ed., vol. 1. Dover Publications, New York. p. 122.

Hull, A.C. and G. Stewart. 1948. Replacing cheatgrass by reseeding with
perennial grass on southern Idaho ranges. J. Am. Soc. Agron. 40:694-703.

Locke, K. and L.C. Burrill. 1994. Bulbous Bluegrass. Pacific Northwest
Extension Publication.

Novak, S.J. and A.Y. Welfley. 1997. Genetic diversity in the introduced
clonal grass *Poa bulbosa* (Bulbous bluegrass). Northwest Sci.
71:271-280.

United States Department of Agriculture. 1948. The Yearbook of
Agriculture: Grass. U.S. Government Printing Office, Washington D.C. pp.
687 -- 688.

Vinall, H.N., and H.L. Westover. 1928. Bulbous bluegrass, *Poa bulbosa*.
J. Am. Soc. Agron. 20:394-399.

Youngner, V.B. 1960. Environmental control of initiation of the
inflorescence, reproductive structures and proliferations in *Poa
bulbosa*. Am. J. Bot. 47:753-757.

Youngner, V.B. and C.M. McKell. 1972. The Biology and Utilization of
Grasses. Academic Press, New York. pp. 390-391.

##### Prepared By:  {#prepared-by .Header-3}

*Pamela Scheinost,* USDA NRCS Plant Materials Center, Pullman,
Washington

*Mark Stannard,* USDA NRCS Plant Materials Center, Pullman, Washington

*Dan Ogle,* USDA NRCS, Boise, ID

##### Species Coordinator:  {#species-coordinator .Header-3}

*Pamela Scheinost,* USDA NRCS Plant Materials Center, Pullman,
Washington

Edited: 072908 ps; 072908 ms; 073008 dgo;

For more information about this and other plants, please contact your
local NRCS field office or Conservation District, and visit the PLANTS
Web site\<[http://plants.usda.gov](http://plants.usda.gov/)\> or the
Plant Materials Program Web site
\<[http://Plant-Materials.nrcs.usda.gov](http://Plant-Materials.nrcs.usda.gov/)\>

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