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Odion [80] found an insignificant (p>0.05) positive effect of heat on small sixweeks grass seedling emergence in laboratory tests. At Vandenburg Air Force Base, California, pre- and postfire soil samples were collected from a maritime chamise community that had not burned for at least 75 years (at Site 1) or 50 years (at Site 2). Prefire soil cores were collected in fall, and both study sites were burned under prescription soon after. Postfire soil samples were also collected [80]. Fire intensity was relatively high (see [81] for fire data). Laboratory treatments for prefire soil samples were a control, heat (100 ²C for 7 min.), and heat with chamise charate. Seedling emergence was counted for pre- and postfire soils samples and in the field on prescribed burn plots. Mean number of germinants/m² emerging from soil samples and on burn plots was [80]:
It is likely that high fire intensities killed small sixweeks grass seed on the prescribed burn sites.
This description provides characteristics that may be relevant to fire ecology, and is not meant for identification. Keys for species identification are available (e.g., [42,67,111]). Lonard and Gould [67] provide a detailed key for identifying infrataxa.
Small sixweeks grass is an annual. Culms are 5.9 to 30 inches (15-75 cm) long and spreading, growing solitary or in small tufts. The inflorescence is a narrow, 0.8- to 9-inch-long (2-24 cm), many-flowered panicle. Spikelets are 5.5 to 10 mm long. Lemmas are 4 to 9.5 mm long, and awned. Awns are relatively long (3.5-20 mm) . The fruit is a caryopsis, ranging from 3.5 to 6 mm in length [22,42,56,67,111].
Small sixweeks grass is native, occurring from southern British Columbia and Montana south to New Mexico and Baja California Norte. It also occurs on the Pacific slope of South America [22,57,105,114].
Distributions of the varieties overlap considerably. Eastwood small sixweeks grass occurs from central Washington south to northern Baja California and western Arizona [67]. Desert small sixweeks grass is distributed from Washington east to western Montana and south to northern Baja California, western Nevada, and southern New Mexico [104,114]. Confusing small sixweeks grass is the least common variety, occurring from south-central Washington to southern California. Pacific small sixweeks grass occurs from Washington east to western Montana and south to Baja California Sur [65,104]. Plants database provides a distributional map of small sixweeks grass and its infrataxa.
The following biogeographic classification systems are a guide to where small sixweeks grass may occur. Except for the West Coast, precise distribution information for small sixweeks grass is limited, and small sixweeks grass may occur in ecosystems and plant communities that are not listed below.
Fire adaptations: Small sixweeks grass establishes from soil-stored seed after fire [25]. No other means of postfire regeneration are documented, although establishment from off-site wind- or animal-dispersal seed is possible.
FIRE REGIMES: Fire is important in retaining open structure in some of the communities where small sixweeks grass is common, but fire was historically infrequent in other plant communities where it occurs. Frequent fire in palouse prairies and annual grasslands maintains the grasslands by preventing invasion of woody plants and reducing litter [82,90,100,115]. Fire plays a more variable ecological role in shrublands where sixweeks grass is important. Some of the shrublands (e.g., chamise (Adenostoma fasciculatum) and other chaparral types) depend on moderate-interval (30-100 years), stand-replacing fire [82]; others are adapted to mixed-severity fires (e.g., big sagebrush (Artemisia tridentata)) [3,21,71,96]; while some desert shrubland types such as creosotebush (Larrea tridentata) are poorly adapted to fire [17]. Descriptions of fire regimes of communities where small sixweeks grass is important follow.
Palouse prairie: Fire frequencies for bluebunch wheatgrass-dominated habitats vary considerably, depending on the associated species [7]. Most mean fire intervals are less than 30 years. Estimates for historical fire intervals in the Snake River Canyon of Idaho for bluebunch wheatgrass-Idaho fescue-Sandberg bluegrass (Festuca idahoensis-Poa secunda) communities are 10 to 25 years [51].
Annual grasslands: Because they are dominated by nonnative annuals, annual grasslands have no "natural" fire regime. There are no data and few historic records of presettlement fire return intervals in pristine California prairie. Probable mean fire intervals (estimates of fire intervals that are derived from historical or very limited physical evidence) for California prairie are frequent: approximately every 1 to 2 years. Probable mean fire intervals for today's annual grasslands are 20 to 30 years [100].
Sagebrush/bunchgrass: Prior to the 1890s, probably only a few grass species occurred in early postfire sagebrush (Artemisia spp.) communities of the Great Basin. Of these, small sixweeks grass and sixweeks grass (Vulpia octoflora) might have been most important. Generally, native Vulpias would increase for a few postfire years, then be suppressed by bunchgrasses such as bluebunch wheatgrass, bottlebrush squirreltail (Elymus elymoides), and Idaho fescue, and by shrubs such as basin big sagebrush (A. tridentata ssp. tridentata) and rabbitbrush (Chrysothamnus spp.) [83]. Historic fire return interval ranged from around 20 to 100 years [46,115,116]. Cheatgrass and medusahead (Taeniatherum caput-medusae), nonnative annual grasses, have altered FIRE REGIMES and successional patterns in some sagebrush communities. Fine fuel loads from dry cheatgrass and/or medusahead can support fire-return intervals as short as 3 to 6 years [83].
Desert shrub: Small sixweeks grass is a common component of southwestern steppe communities. For example, it had 40% frequency in a vegetation survey in a creosotebush-white bursage (Ambrosia dumosa) community in the Mojave Desert [14]. Fire is infrequent in pristine creosotebush-white bursage, Joshua tree (Yucca brevifolia), and saguaro (Carnegiea gigantea) communities. Discontinuity of fine fuels in most years hinders the spread of fire, which was historically uncommon to rare [15,17,19,48,79]. In most years, pristine stand structure of these southwestern desert shrub communities is widely spaced woody plants, bare interspaces, and some perennial bunchgrasses [13,17,18,91]. During wet winters and springs, annuals such as sixweeks grass increase fuels loads. Biomass accumulations from native annuals following an exceptionally wet growing season may provide enough fine fuels to carry a fire in desert ecosystems that otherwise rarely burned [11,102].
Historically, dry sixweeks grass and other native annuals rarely fueled fires in desert shrublands [17], but nonnative, invasive annual grasses including red brome (B. rubens) and schismus have increased fuel loads from historic levels. While native annual grasses mostly grow in the protective shade of shrubs, nonnative grasses also grow in shrub interspaces, increasing fuel continuity and fire frequency and severity on invaded sites. Ecological consequences are serious, as most southwestern desert plants are poorly adapted to frequent and/or stand-replacing fire [17,18]. Nonnative annual grasses outcompete small sixweeks grass on most desert shrub sites (see Invasives). For detailed information on fine fuel production of small sixweeks grass, red brome, schismus, and other Mojave Desert annuals, see the Research Project Summary Nonnative annual grass fuels and fire in California's Mojave Desert.
Chaparral: Historic fire return intervals in chamise and mixed-chaparral ranged from 10 to 90 years [82,101]. Intervals between fires were longer in communities dominated by nonsprouting shrubs, such as bigberry manzanita (Arctostaphylos glauca), than in communities dominated by sprouting shrubs such as chamise [59].
Coastal sage scrub chaparral: Documentation of historic fire intervals in coastal sage scrub is lacking. Current fire return intervals vary widely. Total area burned strongly correlates with precipitation during the previous winter, with heaviest burning occurring after wet years. Fire is rare following drought [72]. Vogl [108] estimated an average fire interval of 20 years for lightning-ignited fire in chaparral adjacent to coastal sage scrub. Fire severity is generally higher in coastal sage scrub than in seral chaparral due to higher litter loading and the higher percentage of terpenes in coastal sage scrub vegetation [34,69]. For a California sagebrush-eastern Mojave buckwheat (Artemisia californica-Eriogonum fasciculatum) community on the Cleveland National Forest, California, fire records show that stand-replacing fire occurs at approximate 28-year intervals. Sixweeks grass is noted in early postfire succession in the community [113].
Fuels: Dry sixweeks grass is a "poor" fuel. Because it contributes little fine fuel biomass and crumbles rapidly upon drying, small sixweeks grass typically contributes little fine fuel biomass during the fire season [17,106]. During prescribed burning on the Mojave Desert, native annual vegetation including sixweeks grass was unable to sustain fire despite abundant growth after above-average winter rains [17].
Productivity on serpentine soils is generally low. Pacific small sixweeks grass biomass on California's serpentine annual grasslands, where Pacific small sixweeks grass is often dominant, averages around 280 g/m² [37,70]. Mean biomass of Pacific small sixweeks grass on serpentine annual grassland of the Jasper Ridge Biological Preserve was 4.4 g/m² over 4 years (mean=1.7 g/m², range=1.8-8.6 g/m² [44].
The following table provides fire return intervals for plant communities and ecosystems where small sixweeks grass is important. 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".
Community or Ecosystem Dominant Species Fire Return Interval Range (years) silver fir-Douglas-fir Abies amabilis-Pseudotsuga menziesii var. menziesii >200 grand fir Abies grandis 35-200 [3] California chaparral Adenostoma and/or Arctostaphylos spp. <35 to <100 sagebrush steppe Artemisia tridentata/Pseudoroegneria spicata 20-70 [82] basin big sagebrush Artemisia tridentata var. tridentata 12-43 [96] mountain big sagebrush Artemisia tridentata var. vaseyana 15-40 [4,21,71] Wyoming big sagebrush Artemisia tridentata var. wyomingensis 10-70 (40**) [107,117] coastal sagebrush Artemisia californica <35 to <100 saltbush-greasewood Atriplex confertifolia-Sarcobatus vermiculatus <35 to <100 desert grasslands Bouteloua eriopoda and/or Pleuraphis mutica 5-100 blue grama-tobosa prairie Bouteloua gracilis-Pleuraphis mutica 82] cheatgrass Bromus tectorum 83,112] California montane chaparral Ceanothus and/or Arctostaphylos spp. 50-100 [82] curlleaf mountain-mahogany* Cercocarpus ledifolius 13-1,000 [5,97] blackbrush Coleogyne ramosissima 82] California steppe Festuca-Danthonia spp. 82,100] western juniper Juniperus occidentalis 20-70 creosotebush Larrea tridentata <35 to <100 [82] wheatgrass plains grasslands Pascopyrum smithii <5-47+ [82,115] pine-cypress forest Pinus-Cupressus spp. <35 to 200 [3] pinyon-juniper Pinus-Juniperus spp. <35 [82] Colorado pinyon Pinus edulis 10-400+ [28,32,58,82] Pacific ponderosa pine* Pinus ponderosa var. ponderosa 1-47 [3] interior ponderosa pine* Pinus ponderosa var. scopulorum 2-30 [3,6,64] mountain grasslands Pseudoroegneria spicata 3-40 (x = 10) [2,3] coastal Douglas-fir* Pseudotsuga menziesii var. menziesii 40-240 [3,75,88] Pacific coast mixed evergreen Pseudotsuga menziesii var. menziesii-Lithocarpus densiflorus-Arbutus menziesii <35 California oakwoods Quercus spp. <35 [3] oak-juniper woodland (Southwest) Quercus-Juniperus spp. <35 to <200 [82] coast live oak Quercus agrifolia 2-75 [35] canyon live oak Quercus chrysolepis <35 to 200 blue oak-foothills pine Quercus douglasii-P. sabiniana <35 Oregon white oak Quercus garryana <35 [3] California black oak Quercus kelloggii 5-30 [82] western redcedar-western hemlock Thuja plicata-Tsuga heterophylla >200 [3] *fire return interval varies widely; trends in variation are noted in the species reviewSmall sixweeks grass grows on mesic to dry sites that are often disturbed [22,42,67]. In Utah it is reported along roadsides and waterways [111]. In Nevada it occurs on open dry or rocky slopes [56]. In Baja California Norte, small sixweeks grass grows in sands on the dry sides of toeslopes [114].
Soils: Small sixweeks grass most commonly grows in loose, sandy soils [67], although it may also grow on clays [42,67]. In California small sixweeks grass prefers open sites, and is often found on thin or heavily compacted soils [95]. Small sixweeks grass tolerates low-nutrient soils [103]. Desert small sixweeks grass, for example, grows on serpentine or shale soils [42]. North of San Francisco, Pacific small sixweeks grass cover was positively correlated with a low soil calcium:magnesium ratio, which is characteristic of serpentine soils, although mean plant biomass was lower for Pacific small sixweeks grass growing on serpentine soils compared to plants on nonserpentine soils [53]. Pacific small sixweeks grass also grows on clay soils with favorable phosphorus and available water contents [89].
Aspect: Eastwood small sixweeks grass was most common on southeast-facing slopes (21% frequency) and least important on northeast-facing slopes (3% frequency) on annual grasslands of the Jasper Ridge Biological Preserve in San Mateo County, California. It only occurred on serpentine soils [70].
Elevation: Small sixweeks grass is documented at the following elevations:
Area Elevation Arizona low to mid-elevations [57] California sea level to 4,900 feet (0-1,500 m) [42,95] Nevada 3,600-6,200 feet (1,200-1,900 m) [56] Utah <6,000 feet (1,830 m) [111]Fire occurring when plants are mature kills small sixweeks grass [24]. Annual grasses may sprout from the root crown when fire occurs early in the growing season [49].
Fire in any season may reduce the seed bank [24]. Small sixweeks grass seed in litter or lying on the soil surface is most vulnerable to fire kill [101,117]. Most surface fires probably do not harm small sixweeks grass seed that is buried in soil [40,80]. However, even buried seed can die when exposed to heat for long periods of time. In laboratory experiments, small sixweeks grass seed buried in moist soil died after a 1-hour exposure to 115 to 121 ²>F (46-49 ²C) temperatures [63], while most Pacific small sixweeks grass seed exposed to temperatures of 160 ²F (70 ²C) for only 5 minutes remained viable. Germination of unscarified Pacific small sixweeks grass seed dropped as follows [101]:
ControlIn another laboratory study, Sweeney [101] tested Pacific small sixweeks grass's maximum heat tolerance at 320 ²F (160 ²C). In a pot experiment, he obtained 100% germination of fresh, untreated Pacific small sixweeks grass seeds buried at 0.25 inch (0.63 cm), while germination dropped to 68% after excelsior was burned on top of similarly treated seeds. Charate slightly lowered germination of Pacific small sixweeks grass seed from 100% to 95% [101].
Overall forage value of small sixweeks grass is generally small due to low productivity [20]. However, small sixweeks grass may show large-volume production in wet years [95]. It usually does not stay green for long [8].
Palatability/nutritional value: Sampson and others [95] rate palatability of green small sixweeks grass as good for cattle and horses and fair for domestic sheep. Initially nutritious, nutritional value drops quickly as plants senesce [95].
Cover value: Vulpia species provide poor cover for small mammals and birds [26].
Small sixweeks grass is most important in California's annual grassland
communities and palouse prairies of the Pacific Northwest. Small sixweeks grass occurs in California riparian scrub vegetation
of the Transverse Ranges. Dominant riparian scrub species include mulefat
(Baccharis salicifolia), Nevada broomsage (Lepidospartum latisquamum),
and/or narrowleaf willow (Salix exigua).
Small sixweeks grass also occurs in riparian California broomsage (L. squamatum)
and/or Nevada broomsage scrub of southeastern California and Nevada [12].
California grasslands:
Small sixweeks grass is common to dominant in California's valleys and low foothills
[41]. On the San Joaquin Experimental Range near Fresno, it
was tallied as the 2nd most common grass over a 5-year period, comprising 9% to
17% cover [95].
It was also important in California's pristine valley grasslands. Small
sixweeks grass was probably abundant in California prairie in favorable years.
Historically, relative proportion of small sixweeks grass and other native
annual grasses was probably greatest on dry sites [40]. Grasslands on serpentine soils
are among the few remnants of California prairie,
because nonnative annual grasses cannot compete with serpentine-adapted native
annual grasses on serpentine sites [47]. Pacific small sixweeks grass is
typically the dominant grass on serpentine soils [74].
Pacific small sixweeks grass is also noted on relict purple needlegrass (Nassella
pulchra) communities [89]. Holland [45] lists Eastwood and Pacific small
sixweeks grasses as dominant with serpentine reedgrass (Calamagrostis
ophitidis) on serpentine bunchgrasslands of the Coast Ranges, Sierra Nevada,
and Transverse Ranges.
Rangeland:
Moderate to heavy grazing may favor small sixweeks grass at the expense of more
palatable perennial grasses [95]. On a clearcut in
northeastern Oregon, small sixweeks grass was slightly more frequent on
cattle-grazed than on big game-grazed plots, showing 4%, 2%, and 3% frequency on
plots used by cattle, big game, and both, respectively [61]. It was also more
common on clipped plots at Carrizo Plain National Monument, California, showing
0.30% on clipped plots and 0.15% cover on ungrazed plots [60]. However,
Pacific small sixweeks grass on the California Natural Reserve
was more frequent on ungrazed than on grazed sites.
On cattle-grazed plots, frequency was 0.3% on nonserpentine soils and 2.1% on serpentine soils,
and 0.6% and 3.3% on ungrazed nonserpentine and serpentine soils,
respectively [39].
Pacific small sixweeks grass greatly increased in cover
following addition of nitrogen fertilizer
on serpentine annual grassland of the Jasper Ridge Biological Preserve,
dominating some fertilized plots to near exclusion of other
species. Density of Pacific small sixweeks grass averaged 290 plants/m²
on fertilized plots and 150 plants/m² on
unfertilized plots. Most annuals (native or not) declined with nitrogen
amendment to the serpentine soil [44].
Invasives:
Nonnative annual grasses can interfere with establishment and growth
of small sixweeks grass. Cheatgrass has relegated small sixweeks grass to
minor status on dry portions of the Columbia Plateau, where
small sixweeks grass was once abundant [66]. In a greenhouse experiment using small sixweeks grass, red
brome (a nonnative species), and pinnate tansymustard (Descurainia pinnata, a native species)
seed from the Mojave Desert, red
brome extracted soil water faster and had higher total plant nitrogen content
compared to small sixweeks grass and pinnate tansymustard. Red brome also showed higher
germination rates compared to small sixweeks grass and pinnate tansymustard,
although small sixweeks grass produced more total seed. A growth chamber study showed
biomass of small sixweeks grass was significantly (p<0.01) reduced when grown
with red brome in nitrogen-fertilized desert soil compared to small sixweeks
grass grown with red brome in unfertilized desert soil [93].
Pacific small sixweeks grass is adapted to low-nitrogen soils and can outcompete
nonnative annual grasses on low-nitrogen serpentine soils. Nonnative Italian ryegrass (Lolium
multiflorum) and soft chess (Bromus hordeaceus) are infrequent on
serpentine soils unless nitrogen is added [29]. In a survey of California annual
grasslands on 92 sites, Pacific small sixweeks grass frequency averaged 48.5% on serpentine sites
and 5.5% on nonserpentine soils. Frequency was not significantly affected by
distance from roads [31].
Small sixweeks grass establishes from soil-stored seed in early postfire plant communities. It is often common after fire [39]. Sampson and others [95] describe recent chaparral burns as "favorite habitat" for small sixweeks grass. In California, Sampson and Burcham [94] noted Pacific small sixweeks grass presence the 1st year after prescribed burning in chamise and mix-shrub chaparral communities in Mendocino and Shasta counties. In a survey on chamise and mixed-shrub chaparral communities of California, Sweeney [101] found small sixweeks grass was "common on 1-year-old burns, becoming increasingly abundant on 2-, 3-, and 4-year-old burns." It was also abundant on open, disturbed sites adjacent to burns [101].
Harrison and others [39] found a significant (p<0.01) soil-fire interaction for Pacific small sixweeks grass on the California Natural Reserve in northern California. Pacific small sixweeks grass frequency (%) was highest on burned serpentine soils [39]:
Soil type
Frequency
burned unburned nonserpentine 0.4% 0.5% serpentine 3.6% 3.1%Daubenmire [23] found a July 1961 wildfire promoted Pacific small sixweeks grass near Clarkston, Washington. The fire occurred in an old field succeeding to a bluebunch wheatgrass-Sandberg bluegrass community. Percent cover of Pacific small sixweeks grass was low under all conditions, but relative frequency increased in early postfire years [23]:
Postfire year 2 Postfire year 4 Postfire year 12 Burned sites Cover (%) 0 1 1 Frequency (%) 0 58 55 Unburned sites Cover (%) 0 trace 1 Frequency (%) 0 18 25Often, fire may have only a slight positive effect to no effect on small sixweeks grass. Small sixweeks grass was present but uncommon on both burned and unburned sites 6 years after wildfire in a blackbrush community in southwestern Utah [15]. In a survey of maritime burns, Eastwood small sixweeks grass had 4% frequency on earl seral burns (postfire years 1-5) in maritime coast live oak in Santa Barbara County, California. It was not present on maritime chamise chaparral burns [25].
Because it is an annual, sixweeks grass regenerates only from seed [54,95]. Published information on small sixweeks grass's reproductive biology is scarce, particularly in regard to seed biology and germination. Further research is needed on regeneration requirements of small sixweeks grass.
Breeding system/pollination: Small sixweeks grass is largely cleistogamous. Gene flow within and among populations is minimal to nonexistent due to cleistogamous habit [54,68]; however, there are occasional chasmogamous plants [54].
Seed production: In a greenhouse study, small sixweeks grass grown in serpentine soil significantly (p=0.05) increased aboveground vegetative and seed biomass when fertilized with either N-P-K with calcium amendment or compost with calcium amendment [78]. Information on small sixweeks grass seed production in the field was not found.
Seed dispersal: Seed is dispersed primarily by wind [1]. The seed awns provide a mechanism for possible animal dispersal, although animal dispersal is not documented.
Seed banking: Small sixweeks grass maintains a seed bank [8,101]. On annual grassland at the Hopland Field Station, California, Vulpia species (V. microstachys, V. bromoides, and V. myuros) had a mean density of 1,227 seeds/dm² in 1974 and 438 seeds/dm² in 1975. Mean seed:germinant ratios were 10:1 and 6:1 in 1974 and 1975, respectively. Vulpia grasses were pooled due to difficulty of identifying species in the field [8]. On a serpentine site near Colusa, California, small sixweeks grass seed density averaged 400/m² [78].
Germination: Few studies to date (2006) address germination requirements of small sixweeks grass. It appears to require neither scarification nor stratification [101,103], although such treatments or processes may increase germination. Desert small sixweeks grass seed collected from the Intermountain region showed 85% mean germination [52]. Sweeney [101] obtained 92.2% mean germination (range=80%-100%) of unstratified, unscarified Pacific small sixweeks grass collected in California.
Small sixweeks grass seed tolerates moderate heat for short periods. In a heat tolerance test, 65% of unscarified Pacific small sixweeks grass seeds that sustained a maximum temperature of 160 ²F (70 ²C) for 5 minutes remained germinable (see IMMEDIATE FIRE EFFECT ON PLANT for further information on this study) [101]. Plant Response to Fire also provides further information on fire effects on small sixweeks grass germination.
As an annual, small sixweeks grass cover may fluctuate from year to year [95], and sometimes no viable seed may germinate in a seemingly favorable germinating season. On the Hopland Field Station, small sixweeks grass and other Vulpia species showed "good" germination at the beginning of the fall growing season, but viable seed was still plentiful in the seed bank in spring [8].
Soil or litter cover may increase germination. In a greenhouse study, Pacific small sixweeks grass germination was improved by covering seed with either 0.3 or 0.5 inch (0.8 or 1.2 cm) of topsoil. Serpentine litter had no effect on germination. Gulmon [36] suggested that Pacific small sixweeks grass seeds benefit from the increased wetting time afforded by topsoil coverage. Pacific small sixweeks grass showed significantly (p=0.007) reduced cover on plots where mulch was removed compared to plots with intact mulch (9.98% and 25.95%, respectively) [60].
Seedling establishment/growth: As of 2006, little information was available on growth rates of small sixweeks grass. Although some small sixweeks grass ecotypes are adapted to serpentine soils, the low calcium levels characteristic of such soils may inhibit seedling root growth [78]. After seedlings at the Hopland Field Station had reached several weeks of age, they suffered little mortality through winter and spring [8].
Asexual regeneration: Because it is an annual, small sixweeks grass does not sprout from the root crown after it produces seed. It dies. However, Vulpia species may die back and sprout from the root crown when wet weather follows a short-term dry period within the growing season [49].
The scientific name of small sixweeks grass is Vulpia microstachys (Nutt.) Benth. (Poaceae) [22,42,67,68,77,105].
In this review, small sixweeks grass varieties are referred to by the common
names given below. Varieties are:
Vulpia microstachys (Nutt.) Benth. var. ciliata (Beal) Lonard & Gould [67],
Eastwood small sixweeks grass
Vulpia microstachys (Nutt.) Benth. var. confusa (Piper) Lonard & Gould [67,68],
confusing small sixweeks grass
Vulpia microstachys (Nutt.) Benth. var. microstachys [22,67,68],
desert small sixweeks grass
Vulpia microstachys (Nutt.) Benth. var. pauciflora (Beal) Lonard & Gould [22,42,55,67],
Pacific small sixweeks grass
The genus Vulpia is distinguished by annual life form and cleistogamous
breeding habit, while Festuca is perennial and chasmogamous [67].
Not all systematists support the separation of these closely aligned genera [33,84,109,111].
Vulpia microstachys is a species of grass known by the common names small fescue and small sixweeks grass. It is native to western North America from British Columbia to Colorado and New Mexico to Baja California, where it grows in many types of open habitat, including grasslands. It is dominant on some grasslands of California, and it was probably an abundant native grass before the habitat was altered by invasive non-native grasses.[1] It occurs on serpentine soils with associates such as serpentine reedgrass (Calamagrostis ophitidis).[1] It is also known from parts of South America.[1] It is an annual grass producing one stem or a clump of several stems growing up to 75 centimeters tall. The inflorescence has several open branches bearing clusters of purple-tinged spikelets. The spikelet has one to six flowers. The grass is usually cleistogamous, its flowers fertilizing themselves.[1]
There are four varieties which are sometimes difficult to tell apart; they are separated on the basis of the arrangement and amount of hairs on the spikelets.[2]
Vulpia microstachys is a species of grass known by the common names small fescue and small sixweeks grass. It is native to western North America from British Columbia to Colorado and New Mexico to Baja California, where it grows in many types of open habitat, including grasslands. It is dominant on some grasslands of California, and it was probably an abundant native grass before the habitat was altered by invasive non-native grasses. It occurs on serpentine soils with associates such as serpentine reedgrass (Calamagrostis ophitidis). It is also known from parts of South America. It is an annual grass producing one stem or a clump of several stems growing up to 75 centimeters tall. The inflorescence has several open branches bearing clusters of purple-tinged spikelets. The spikelet has one to six flowers. The grass is usually cleistogamous, its flowers fertilizing themselves.
There are four varieties which are sometimes difficult to tell apart; they are separated on the basis of the arrangement and amount of hairs on the spikelets.
V. m. var. ciliata - Eastwood fescue V. m. var. confusa - confusing fescue V. m. var. microstachys - desert fescue V. m. var. pauciflora - Pacific fescueVulpia microstachys là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (Nutt.) Munro miêu tả khoa học đầu tiên năm 1857.[1]
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Vulpia microstachys là một loài thực vật có hoa trong họ Hòa thảo. Loài này được (Nutt.) Munro miêu tả khoa học đầu tiên năm 1857.
