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Species
Poa pratensis L.
IUCN
NCBI
EOL Text
1.1 Descripción de la especie
Culmos rizomatosos en macollas densas, de 20 a 60 (-100) cm de altura. Vainas lisas o escábridas. Lígulas de 0.2 a 3 mm de largo, truncada. Láminas planas o conduplicadas, de 10 a 30 cm de largo por 2 a 3 mm de ancho. Inflorescencia una panícula abierta, piramidal, de 5 a 15 cm de largo por 3 a 5 cm de ancho, ramas flexuosas, desnudas en la mitad o 2/3 inferiores. Espiguillas (2-) 3 a 5-flosculadas, de 4 a 6 mm de largo, verdes o purpúreas. Glumas ligeramente desiguales, escábridas en la quilla, la primera de 2 a 3 mm de largo, 1 o 3-nervada, la segunda 2.6 a 3.7 mm, 3- nervada. Lemas de 2 a 3 (-4) mm de largo, obtusas o agudas, la quilla y nervios laterales pilosos, con un mechón de pelos lanosos muy notorio en la base. Páleas escabriúsculas en las quillas, de 2 a 3 mm de largo. Flor con anteras de 1.5 a 2 mm de long; cariópside encerrado, oblongo de 1.6 mm de long, glabro (Beetle, et al., 1999; Burkart, 1969 &Rzedowski &Rzedowski, 2001).
License | http://creativecommons.org/licenses/by-nc-sa/2.5/ |
Rights holder/Author | CONABIO |
Source | No source database. |
Perennials, loosely tufted or with isolated shoots, strongly rhizomatous, often forming turf; shoots extra- and often intravaginal. Plants green to pale or yellowish green, or purplish to strongly grayish glaucous. Culms 10–120 cm, 1–2.5 mm in diam., erect or decumbent, 1 to several per tuft, smooth, nodes (1–)2–4, 1 or 2 exserted. Leaf sheaths moderately compressed and keeled, uppermost closed for (1/4–)1/3–2/5 of length, smooth or infrequently retrorsely scabrid or pilulose; blades flat or folded, papery to thickly papery, 1–5 mm wide, surfaces smooth or sparsely scabrid, margins scabrid, adaxially glabrous or frequently sparsely hispidulous to strigulose, of tillers, flat or folded with margins inrolled, intravaginal ones when present often folded, 0.5–2 mm wide, extravaginal ones flat or folded (1–)1.5–5 mm wide; ligule whitish, 0.5–4(–5) mm, abaxially nearly smooth to densely scabrid, apex truncate to rounded, often finely scabrid to ciliolate or pilulose. Panicle loosely contracted to open, oblong to broadly pyramidal, erect or slightly lax, (2–)5–20(–25) cm, longest internodes 1–4.2 cm; branches steeply ascending to widely spreading, (2–)3–5(–9) per node, rounded or distally angled, nearly smooth to distally scabrid with hooks on and between angles, longest branch 1.5–5(–10) cm with (3–)7–18 spikelets in distal 1/3–2/3, sometimes clustered distally. Spikelets ovate, green or grayish, frequently purple tinged, 3–7(–9) mm, florets 2–5(–9); vivipary absent in China; rachilla internodes 0.5–1(–1.2) mm, smooth, glabrous (rarely sparsely pilulose); glumes subequal, strongly keeled, keels and sometimes lateral veins dorsally scabrid, first glume 1.5–3(–4) mm. 1–3-veined, upper glume 2–4 mm, 3(or 5)-veined; lemmas ovate to lanceolate (or narrowly lanceolate), 2.5–4(–5) mm, apex slightly obtuse to acuminate, keel villous for 3/4 of length, marginal veins to 1/2 length, intermediate veins prominent, glabrous (rarely sparsely pilulose), glabrous between veins, minutely bumpy, sparsely scabrid distally; callus webbed, hairs as long as lemma, frequently with less well-developed tufts from below marginal veins; palea usually narrow, glabrous or with sparse hooks, usually minutely bumpy, glabrous between keels, keels scabrid, infrequently medially pilulose in subsp. pruinosa. Anthers (1.2–)1.4–2.5(–2.8) mm, infrequently poorly formed, but not vestigial. Fl. and fr. Jun–Sep. 2n = 28–144.
License | http://creativecommons.org/licenses/by-nc-sa/3.0/ |
Rights holder/Author | eFloras.org Copyright © Missouri Botanical Garden |
Source | http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200026035 |
More info for the terms: cool-season, cover, prescribed fire, warm-season
Burning for bluegrass control: Frequent (annual or biennial) late
spring burning can be used to control Kentucky 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 Kentucky 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.
In mixed-grass prairie, mid-May has proven to be the most effective time
to burn for Kentucky bluegrass control and has resulted in concomitant
increases in warm-season grasses [31,83]. In native bluestem prairie in
eastern Kansas, Kentucky bluegrass has been nearly eliminated from sites
annually spring burned for decades [112]. In aspen parkland in
northwestern Minnesota, 13 years of annual spring burning in late April,
when bluegrass was 4 to 6 inches high (10-15 cm), reduced Kentucky
bluegrass to about half its original percent composition [107]. After
10 years of biennial spring burning on the Curtis Prairie on the
University of Wisconsin Arboretum, Kentucky bluegrass frequency
decreased from 60 to 13 percent [6].
Burning to promote bluegrass growth: When using prescribed fire to
promote the growth of cool-season species in the Northern Great Plains,
Kentucky bluegrass will probably respond best to very early spring
(March-April) or late summer (August-September) fires [130].
Disease control: In Kentucky bluegrass commercial seed fields, burning
after harvest successfully controls several diseases. It is effective
in controlling ergot (Claviceps purpurea); silver top, caused by the
fungus Fusarium trianctum; and the mite, Siteroptes cerealium. Burning
also helps control leaf rust (Puccinia poae-nemoralis) and other fungi
harbored in crop residue [48].
Wildlife considerations: Succulent new grass shoots arising from burned
mountain grasslands are highly palatable to wildlife. On the Front
Range in Colorado, mule deer and bighorn sheep ate considerably more
Kentucky bluegrass on areas burned in late September than on nearby
unburned areas [102]. Following late October and early November fires
in aspen stands in Colorado, Kentucky bluegrass cover increased and thus
provided more forage to wildlife [99].
Where Kentucky bluegrass is desired for providing ruffed grouse drumming
ground cover, it can be burned when the soil is damp and plants are
dormant [122].
Burning under aspen: Powell [90] reported that in south-central
Colorado, aspen/Kentucky bluegrass communities have only a moderate
probability of carrying a prescribed fire and only if livestock grazing
is deferred for at least one season. For fall prescribed burning, the
likelihood of a relatively uniform burning treatment may be increased by
burning after aspen leaf fall [99].
Ecosystem withstands attack: Kentucky bluegrass
Lawn ecosystems such as that of Kentucky bluegrass survive attack by weeds by maintaining network connections, community components, and stability.
"What the threatened lawn must do is take advantage of what makes it different from the weed. For where weeds are, par excellence, solitary hunters, lawn grass is overwhelmingly a tightly grouped species. Most grass blades on your lawn are over eight months old, and some will be over twenty months old. But even more importantly, the whole community of lawn grass might have been growing in the same place for years. And in that time, all stable and steady, it will have had time to acquire friends. Lots and lots of minature friends." [goes on to mention bacteria and fungus]
"There's an entire cabled-up network under your lawn, connecting all the grass roots. It's been building up for the whole life of your lawn and by now can easily shunt liquid food supplies from a well-supplied sector to a threatened one. The weed, though tracking the sun with its antenna and trying like mad to grow fresh roots of its own, can't compete with a system this large and long-established…A single square yard of lawn planted with Kentucky bluegrass can have ten billion root probes. Even if only a fraction of them have had time to build up the connecting fungus cables, that's still many millions of links, and so an extraordinary volume of subterranean space from which any threatened grass blade can, via the shunting network, draw help." (Bodanis 1992:165)
Learn more about this functional adaptation.
- Bodanis, D. 1992. The Secret Garden: Dawn to Dusk in the Astonishing Hidden World of the Garden. Simon & Schuster. 187 p.
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | (c) 2008-2009 The Biomimicry Institute |
Source | http://www.asknature.org/strategy/ea42c00d49be85a56850d6df0436f3a0 |
Kentucky bluegrass is one of America's most popular lawn grasses. It
withstands considerable abuse, and it is often used as a sod-grass at
campgrounds, golf courses, and ski slopes [97].
General: Grass Family (Poaceae). Kentucky bluegrass is a cool-season perennial sod-forming grass. The roots are shallow, often within the upper 8 cm of the soil surface. Stems are 30 to 90 cm tall. Leaves are attached to the base of the stem, folded and sometimes hairy at the point of attachment, have flat blades, are 2 to 5 mm wide and 10 to 40 cm long. The inflorescence is an open panicle consisting of two to six flowers. The lemmas have a tuft of cobwebby hairs. Flowering starts in May and fruit is mature by mid-June.
Kentucky bluegrass is distinguished from Canada bluegrass (Poa compressus) by its darker green foliage, longer leaves, and pubescence at the bases of the leaves.
Distribution: Kentucky bluegrass is native to portions of North America, including areas within the United States. Exact delineation of native status has not been determined, but data seems to indicate that it is native in parts of the southeast, northeast, and upper Midwest regions and introduced or naturalized elsewhere. It occurs throughout the United States although it is most prevalent in the northern half. It is not common in the Gulf States or in the desert regions of the southwest. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site (http://plants.usda.gov).
Habitat: Kentucky bluegrass is promoted on sites that have cool and humid climates. It is found in uplands and lowlands of the tallgrass prairie and in the lowlands of mixed-grass prairies where adequate precipitation falls. In the west, it is found on northern exposures at mid to high elevations. In the southwest and California, it is found in cool mountainous regions.
It frequently occurs as an understory dominant in aspen habitats throughout the Intermountain Region, ponderosa pine, sagebrush/bunchgrass, and bunchgrass habitats throughout the U.S., and riparian habitats in the Mountain West. It is also a common dominant of Midwestern prairies.
The genus Poa is distinguished by its flat leaf blades, 2-6 flowered panicles, 1-3 nerved glumes and tuft of cobwebby hairs at the base of the 5-nerved lemmas (Gleason 1957, Mohlenbrock 1972, Hitchcock 1950).
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | N. SATHER, MRO, NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Poa+pratensis |
More info for the terms: cover, density, restoration
In the Mountain West, Kentucky bluegrass is often more abundant in
recently burned areas than in nearby unburned areas. Sampling 2- to
36-year-old burns in sagebrush/grassland habitat types in southeastern
Idaho, Humphrey [56] found that Kentucky bluegrass was more abundant in
recent than in old burns. McKell [76] compared four different-aged
burns in the Gambel oak (Quercus gambelii) zone of north-central Utah.
Kentucky bluegrass cover and density were higher 1 year after a November
fire and 2 years after a January fire, but on 9- and 18-year-old burns
cover and density were the same as on nearby unburned areas.
In the Klamath Mountains of southern Oregon, Kentucky bluegrass was a
codominant grass in open ponderosa pine stands that were burned annually
in the spring for 16 years [123].
The following Research Project Summaries provide information on prescribed
fire use and postfire response of plant community species including
Kentucky bluegrass:
- Response of vegetation to prescribed burning in a Jeffrey pine-California
black oak woodland and a deergrass meadow at Cuyamaca State Park, California - Effects of fall and spring prescribed burning in
sagebrush steppe in east-central Oregon - Vegetation response to restoration treatments in ponderosa pine-Douglas-fir
forests of western Montana - Vegetation changes following prescription fires in quaking aspen stands
of
Colorado's Front Range - Seasonal fires in Saskatchewan rough fescue prairie
Canada
Rounded National Status Rank: N5 - Secure
United States
Rounded National Status Rank: NNR - Unranked
License | http://creativecommons.org/licenses/by-nc/3.0/ |
Rights holder/Author | NatureServe |
Source | http://explorer.natureserve.org/servlet/NatureServe?searchName=Poa+pratensis |
Livestock: Kentucky bluegrass is highly palatable in early growth stages
and provides nutritious forage for all classes of livestock. In the
West, it is often abundant in mountain grasslands, moist and dry
mountain meadows, aspen parkland, and open ponderosa pine forests where
it is eaten extensively by domestic sheep and cattle [15,20,49,60].
Mountain meadows dominated by Kentucky bluegrass may be relatively
limited in extent, but they are highly productive and thus contribute
substantial amounts of summer forage [75]. On mountain rangelands in
northeastern Oregon, Kentucky bluegrass is one of the most important
forage species in cattle and sheep summer diets [55,75].
In eastern North America, Kentucky bluegrass is considered one of the
best pasture grasses [100]. Due to limited precipitation in the West,
however, it provides only fair range forage because biomass production
is relatively low due to summer dormancy [115]. It is seldom seeded on
western ranges but may be used for pasture on moist and cool sites
[100,122]. In irrigated pastures, midsummer production can be
favorable, allowing cattle to gain more weight than if pastured on
orchard grass (Dactylis glomerata) or smooth brome (Bromus inermis)
[100].
Kentucky bluegrass is seldom planted for hay production because yields
are generally low, and plants mature before other hay species are ready
to cut. It is, however, often found in hay mixtures as an invader
[100].
Wildlife: Regionally, Kentucky bluegrass can be an important part of
the diets of elk, mule deer, and bighorn sheep [27,49]. On elk winter
range in Rocky Mountain National Park, Colorado, Kentucky bluegrass is
one of the most important grasses eaten by elk [54]. Kentucky bluegrass
is also an important part of fall and winter diets of elk in Wind Cave
National Park, South Dakota [126]. Kentucky bluegrass meadows found
along mountain streams are often preferred foraging areas of wild
ungulates [61].
Bluegrass leaves and seeds are eaten by numerous species of small
mammals and songbirds [72,85]. Bluegrass is often an important food of
the cottontail rabbit and wild turkey [21,39]. Prairie chickens eat
small amounts of seeds [21]. Kentucky-bluegrass-dominated grasslands
provide habitat for numerous species of small mammals [39,78]. In
Kentucky-bluegrass-dominated mountain meadows in Oregon the northern
pocket gopher, Columbian ground squirrel, and mice are a prevalent, and
thus these sites are also important to foraging raptors [62].
Mueggler and Campbell [82] suggest that the aspen/Kentucky bluegrass
community type in Utah is one of the poorest aspen community types for
value as wildlife habitat because of the lack of plant species
diversity.