扁桿早熟禾

Foodplant / parasite
Blumeria graminis parasitises live Poa compressa

Foodplant / saprobe
colony of Cercosporidium dematiaceous anamorph of Mycosphaerella recutita is saprobic on dead sheath of Poa compressa

Foodplant / parasite
hypophyllous, long covered by epidermis telium of Puccinia brachypodii var. poae-nemoralis parasitises live leaf of Poa compressa

Poa compressa is native to W Eurasia. It is infrequent in China and is perhaps present only as an introduction in C to E Russia and China. It is distinguishable by its strong rhizome system, long, open sheaths, compressed culms and nodes, and scabrid-angled panicle branches. It is a good soil binder in riparian habitats. It is expected in Heilongjiang because it is frequent on the Russian side of the Chinese border.

Perennials, strongly rhizomatous, shoots extravaginal. Culms wiry, compressed, erect, often geniculate at base, simple or sparsely tufted, 15–50(–60) cm tall, 1.5–2 mm wide, nodes compressed, 3–6, 2–5 exserted. Leaf sheaths compressed to keeled, smooth, uppermost closed for 1/10–1/5 of length; blades flat, 5–12 cm × 1.4–4 mm, surfaces smooth or adaxially scabrid; ligule 1–3 mm, abaxially scabrid, truncate to obtuse. Panicle contracted or slightly open, erect, narrow, 4–11 × 0.5–1(–3) cm; branches erect or steeply ascending, or eventually spreading, 1–3 per node, densely scabrid angled from base, longest 2–4 cm with spikelets moderately crowded from the base or in distal 2/3. Spikelets ovate-lanceolate, 3.5–5 mm, florets 2–4; glumes lanceolate, nearly equal, 2–3 mm, 3-veined, apex acute or thinly mucronate, keel scabrid, rachilla smooth or minutely bumpy; lemmas oblong, 2.3–3.5 mm, apex obtuse, keel shortly villous for 2/3 of length, marginal veins to 1/3, intermediate veins faint, areas between veins glabrous; callus sparsely webbed or glabrous; palea keels scabrid. Anthers 1.3–1.8 mm. Fl. and fr. Jun–Aug. 2n = 14, 35, 42, 45, 49, 50, 56, 59.

Moist grassy places in forests. Hebei, Jiangxi, Qinghai, Shandong, Taiwan, Xinjiang, Yunnan [India (Himachal Pradesh), Japan, Kazakhstan, Russia (Far East, Siberia); Africa, SW Asia, Australia, Europe, North and South America, Pacific Islands].

More info for the terms: prescribed fire, restoration

The Research Project Summary Vegetation response to restoration treatments
in ponderosa pine-Douglas-fir forests of western Montana provides information
on prescribed fire and postfire response of plant community species,
including Canada bluegrass, that was not available when this species
review was written.

Canada bluegrass

Canada bluegrass provides fair to good "environmental protection" for
upland game birds, waterfowl, nongame birds, and small mammals [6].

More info for the term: cool-season

Canada bluegrass is an introduced, perennial, cool-season, erect,
sod-forming grass.  Culms are solitary or loosely tufted, flattened, and
10 to 24 inches (25-60 cm) tall.  The inflorescence is a compressed
panicle [10,18,33]

Canada bluegrass has a "dense creeping root system" and "long rhizomes"
but does not form as dense a sod as Kentucky bluegrass (Poa
pratensis) [12,18,32].

In North America, Canada bluegrass is distributed from Newfoundland to
Alaska, and south throughout most of the United States.  Hitchcock [16]
lists Georgia, Tennessee, Alabama, Oklahoma, New Mexico, and California
as the southern extent of its range.

More info for the terms: density, fire regime, grassland, rhizome

During grassland fires, the fire front passes quickly and temperatures 1
inch (2.5 cm) below the soil surface rise very little [5].  Located a
couple of inches below the soil surface, Canada bluegrass rhizomes
survive and initiate new growth after aboveground plant portions are
consumed by fire.  Although the plant survives because of soil-insulated
rhizomes, postfire plant vigor and density are greatly affected by
phenological stage at time of burning (see Fire Effects On Plant).

Information regarding the importance that seedling establishment plays
in Canada bluegrass immediate postfire recovery was not found in the
literature.  Postfire growth is assumed to be primarily due to rhizome
survival.

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".

More info for the terms: cool-season, warm-season

Annual or biennial late spring burning can be used to control Canada
bluegrass and promote the growth of warm-season grasses in the Midwest.
The timing of burning is critical and should take place just prior to
the resumption of warm-season grass growth.  Such burning favors
warm-season grasses because they are dormant at the time of burning.
Conversely, cool-season species like Canada bluegrass are harmed by late
spring fire because they resume growth in the early spring and are thus
actively growing at the time of burning [15].

More info on this topic.

More info for the term: geophyte

  
   Geophyte

More info for the term: association

Canada bluegrass is unable to compete with other grasses on good soils
and generally develops best on soils of low fertility or poor drainage
[12,25].  It has moderate drought and salinity tolerances but is not
shade tolerant [8,12,30].  It grows about anywhere Kentucky bluegrass
grows but only achieves dominance on soils that are too acid, droughty,
or nutrient-deficient for Kentucky bluegrass dominance [18].  It grows
on disturbed sites in innumerable habitats across North America.  In the
Pacific Northwest, Canada bluegrass is commonly found in association
with wheatgrasses (Agropyron spp.) and hairgrasses (Deshampsia spp.),
and often grows in pure stands on poor soils [30].

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

    15  Red pine
    20  White pine - northern red oak - red maple
    21  Eastern white pine
    25  Sugar maple - beech - yellow birch
    33  Red spruce - balsam fir
    35  Paper birch - red spruce - balsam fir
    42  Bur oak
    52  White oak - black oak - northern red oak
   107  White spruce
   110  Black oak
   210  Interior Douglas-fir
   217  Aspen
   218  Lodgepole pine
   220  Rocky Mountain juniper
   227  Western redcedar - western hemlock
   235  Cottonwood - willow
   236  Bur oak
   237  Interior ponderosa pine
   238  Western juniper
   239  Pinyon - juniper

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

More info for the term: shrub

   FRES10  White - red - jack pine
   FRES11  Spruce - fir
   FRES14  Oak - pine
   FRES15  Oak - hickory
   FRES17  Elm - ash - cottonwood
   FRES18  Maple - beech - birch
   FRES19  Aspen - birch
   FRES20  Douglas-fir
   FRES21  Ponderosa pine
   FRES23  Fir - spruce
   FRES26  Lodgepole pine
   FRES28  Western hardwoods
   FRES29  Sagebrush
   FRES34  Chaparral - mountain shrub
   FRES35  Pinyon - juniper
   FRES36  Mountain grasslands
   FRES37  Mountain meadows
   FRES38  Plains grasslands
   FRES39  Prairie
   FRES42  Annual grasslands

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

   K002  Cedar - hemlock - Douglas-fir forest
   K011 Western ponderosa forest
   K012 Douglas-fir forest
   K013  Cedar - hemlock - pine forest
   K015  Western spruce - fir forest
   K016  Eastern ponderosa forest
   K017  Black Hills pine forest
   K018  Pine - Douglas-fir forest
   K019  Arizona pine forest
   K021  Southwestern spruce - fir forest
   K030  California oakwoods
   K037  Mountain-mahogany - oak scrub
   K038  Great Basin sagebrush
   K047  Fescue - oatgrass
   K048  California steppe
   K051  Wheatgrass - bluegrass
   K052  Alpine meadows and barren
   K055  Sagebrush steppe
   K056  Wheatgrass - needlegrass shrubsteppe
   K063  Foothills prairie
   K064  Grama - needlegrass - wheatgrass
   K066  Wheatgrass - needlegrass
   K067  Wheatgrass - bluestem - needlegrass
   K074  Bluestem prairie
   K075  Nebraska Sandhills prairie
   K081  Oak savanna
   K093  Great Lakes spruce - fir forest
   K095  Great Lakes pine forest
   K096  Northeastern spruce - fir forest
   K098  Northern floodplain forest
   K099  Maple - basswood forest
   K100  Oak - hickory forest
   K104  Appalachian oak forest
   K016  Eastern ponderosa forest
   K107  Northern hardwoods - fir forest
   K108  Northern hardwoods - spruce forest

More info for the term: herbaceous

Plant phenological stage at time of burning greatly influences fire
damage to herbaceous plants.  In general, as new foliage of perennial
grasses reaches full development major food reserves have been depleted,
so that plants are injured most from fires occurring at this time [5].
Late spring fires, after plants have been growing for about a month or
more, appear to be the most damaging to Canada bluegrass.

Canada bluegrass is good forage for cattle, horses, and sheep [3,25].
It has favorable curing properties; horses pastured on Canada bluegrass
in the autumn and early winter maintain their condition [12].  In South
Dakota it is seldom abundant enough to be a principal forage but is
important to livestock because of its wide distribution [18].

In the Rocky Mountains, Canada bluegrass may be a valuable winter,
spring, and fall forage for elk [20].  Mule deer consume it lightly in
the spring [21].

Bluegrass leaves and seeds are eaten by numerous species of small
mammals and songbirds, and may form an important part of the diet of the
cottontail rabbit and wild turkey [3,22].  Prairie chickens eat small
amounts of the seeds [3].

More info for the term: graminoid

Graminoid

Canada bluegrass is classed as an invader of overgrazed rangelands [31].
It is generally not recommended for seeding as a pasture grass because
of its low productivity, but locally it may be useful as pasture on poor
soils [27,33].  It is resistant to grazing and trampling but may be slow
to recover from overgrazing [27].

More info for the term: fresh

Early growth stages of Canada bluegrass are nutritious.  The National
Academy of Sciences [23] reported the following nutritional information
for fresh aerial parts of immature (before inflorescence emergence)
Canada bluegrass (percentage of dry matter):

        Ash 9.1
        Crude fiber 25.5
        Ether extract 3.7
        N-free extract 43
        Protein (N X 6.25) 18.7

     AK  AZ  AR  CA  CO  CT  DE  GA  HI  ID
     IL  IN  IA  KS  KY  ME  MD  MA  MI  MN
     MO  MT  NE  NV  NH  NJ  NM  NY  NC  ND
     OH  OK  OR  PA  RI  SC  SD  TN  UT  VT
     VA  WA  WV  WI  WY  AB  BC  MB  NB  NF
     NT  NS  ON  PE  PQ  SK  YT

Canada bluegrass is palatable to livestock from early spring until late
fall [12].  It is most palatable in spring and fall when it is green and
succulent.  Because it matures later than Kentucky bluegrass (Poa
pratensis) and is drought tolerant, it remains relatively palatable
during the summer [27].

Livestock and wildlife use of Canada bluegrass in western states is
rated as follows [6]:

                         CO      MT      ND      UT      WY
Cattle                  good    good    good    good    good
Sheep                   good    good    good    good    good
Horses                  good    good    good    good    good
Pronghorn               ----    ----    ----    good    good
Elk                     ----    fair    ----    good    good
Mule deer               ----    poor    ----    good    good
White-tailed deer       ----    poor    ----    ----    good
Small mammals           ----    ----    ----    good    good
Small nongame birds     ----    ----    ----    good    good
Upland game birds       ----    ----    ----    fair    good
Waterfowl               ----    ----    ----    fair    fair

More info on this topic.

More info for the term: cool-season

Although a cool-season species, Canada bluegrass matures later than
Kentucky bluegrass, and has little fall regrowth [18].

Flowering time in western states is as follows [6]:

Colorado - June to August
Montana - June to August
North Dakota - June to July
Wyoming - June to August

More info for the terms: density, fire frequency, frequency

Season of burning and frequency of burning greatly influence Canada
bluegrass postfire recovery.  Dormant-season fires favor Canada
bluegrass, and biomass and density may increase during postfire year 1.
Late spring burning, when plants are actively growing, reduces biomass
and density during postfire year 1, but biomass and density may return
to preburn levels within 1 or 2 years.  Thus Canada bluegrass often
recovers within 1 or 2 years after a single late spring fire, but
density and biomass are progressively reduced if burned annually or
biennially in late spring.

In abandoned fields in southern Wisconsin, Canada bluegrass flowering
stem density was reduced 50 percent when burned annually in May for 5
years.  Conversely, flowering stem density increased 170 and 440
percent following 5 years of annual burning in March or October,
respectively [4].  A similar study in southern Wisconsin found that 3
years of annual burning in mid-May reduced Canada and Kentucky bluegrass
flowering stem density by 70 percent, while late March or early April
burning had little affect on flowering [14].

In a reconstructed tallgrass prairie in Illinois, bluegrass (Poa
compressa and P. pratensis combined) percent relative biomass decreased
as fire frequency increased in two communities as follows [11]:

                               Burning Treatment* 
                 not burned     burned twice    burned      burned
                                               3 times     4 times
Community type
big bluestem        23.4**           18.3         4.6          0
indiangrass         18.6             15.9         3.3          0

*not burned = unburned for 19 years
 burned twice = burned Feb. 28, 1952 and April 16, 1959
 burned three times = burned Feb. 28, 1952; April 16, 1959; and May 2, 1961
 burned four times = burned Feb. 28, 1952; April 16, 1959; May 2, 1961; and
                     May 10, 1962

**sampled at the end of the 1962 growing season

In oak (Quercus spp.) woods and goldenrod (Solidago spp.) fields
accidently burned between April 6 and May 2 in south-central New York,
Canada bluegrass frequency increased from 6 to 17 percent and 56 to 81
percent, respectively, 10 to 26 months after burning [28].

After early May prescribed burning in seral brushfields in northern
Idaho, Canada bluegrass recovered rapidly on lightly burned plots.
During the first postfire growing season, it produced the bulk of grass
biomass on lightly burned plots, which was 135 pounds per acre (151
kg/ha).  In comparison, grass production on heavily burned and control
plots averaged only 0.7 and 10.2 pounds per acre (0.8 and 11.4 kg/ha),
respectively [17].

More info for the terms: herb, rhizome

   Rhizomatous herb, rhizome in soil

More info for the term: seed

Canada bluegrass reproduces by both seed and rhizomes [30].  There are
2.5 million cleaned seeds per pound (5.5 million/kg).  Seeds require
light for germination, and germinate best at temperatures fluctuating
between 59 and 86 degrees Fahrenheit (15 and 30 deg C).  Germinative
capacity is 75 to 80 percent [8].

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

    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

More info on this topic.

Obligate Initial Community Species

Canada bluegrass is an early colonizer of disturbed soils [18].

The currently accepted scientific name of Canada bluegrass is Poa
compressa L. [10,33]. There are no recognized varieties or subspecies.

More info for the terms: cover, reclamation

Canada bluegrass is often used for cover and erosion control on
roadsides, road cuts and fills, borrow pits, dam sites, and recreational
areas.  It is often seeded with legume mixtures for revegetation of
mined areas.  It is often slow to establish but once established
provides good cover and long-term growth.  The performance of seeded
Canada bluegrass in mined-land reclamation has been summarized [12].

Perennials, Terrestrial, not aquatic, Rhizomes present, Rhizome elongate, creeping, stems distant, Stems nodes swollen or brittle, Stems erect or ascending, Stems geniculate, decumbent, or lax, sometimes rooting at nodes, Stems solitary, Stems caespitose, tufted, or clustered, Stems compressed, flattened, or sulcate, Stem internodes hollow, Stems with inflorescence less than 1 m tall, Stems, culms, or scapes exceedin g basal leaves, Leaves mostly basal, below middle of stem, Leaves conspicuously 2-ranked, distichous, Leaves sheathing at base, Leaf sheath mostly open, or loose, Leaf sheath smooth, glabrous, Leaf sheath or blade keeled, Leaf sheath and blade differentiated, Leaf blades linear, Leaf blades 2-10 mm wide, Leaf blades mostly flat, Leaf blade margins folded, involute, or conduplicate, Leaf blades mostly glabrous, Leaf blades more or less hairy, Ligule present, Ligule an unfringed eciliate membrane, Inflorescence terminal, Inflorescence a contracted panicle, narrowly paniculate, branches appressed or ascending, Inflorescence solitary, with 1 spike, fascicle, glomerule, head, or cluster per stem or culm, Inflorescence with 2-10 branches, Inflorescence branches more than 10 to numerous, Flowers bisexual, Spikelets pedicellate, Spikelets laterally compressed, Spikelet less than 3 mm wide, Spikelets with 3-7 florets, Spikelets solitary at rachis nodes, Spikelets all alike and ferti lle, Spikelets bisexual, Spikelets disarticulating above the glumes, glumes persistent, Spikelets disarticulating beneath or between the florets, Rachilla or pedicel glabrous, Glumes present, empty bracts, Glumes 2 clearly present, Glumes equal or subequal, Glumes distinctly unequal, Glumes shorter than adjacent lemma, Glumes keeled or winged, Glumes 3 nerved, Lemmas thin, chartaceous, hyaline, cartilaginous, or membranous, Lemma similar in texture to glumes, Lemma 5-7 nerved, Lemma glabrous, Lemma body or surface hairy, Lemma apex acute or acuminate, Lemma awnless, Lemma margins thin, lying flat, Lemma straight, Callus or base of lemma evidently hairy, Callus hairs shorter than lemma, Lemma with long cobwebby white hairs, Palea present, well developed, Palea about equal to lemma, Palea 2 nerved or 2 keeled, Stamens 3, Styles 2-fid, deeply 2-branched, Stigmas 2, Fruit - caryopsis, Caryopsis ellipsoid, longitudinally grooved, hilum long-linear.

Poa compressa, the Canada bluegrass or flattened meadow-grass, is a perennial flattened meadow grass, similar to common meadow-grass, Poa pratensis. It is native to Europe but it can be found nearly worldwide as an introduced species. It grows in old wall tops, pavement cracks, dry stony grassland, and many types of wild habitat. It has a flattened stem, 23–30 cm tall, a close one sided panicle of grey green, with purple florets.

The ligule is rounded.