|© 2005 James L. Reveal, University of Maryland|
Phlox canescens Torr. & Gray
= Phlox hoodii ssp. canescens [61,70,72,88]
Phlox hoodii var. canescens (Torr. & Gray) M. E. Peck [37,62]
= Phlox hoodii ssp. canescens (Torr. & Gray) Wherry [70,94]
Phlox lantana Piper 
= Phlox hoodii ssp. lantana (Piper) Munz [70,71]
Phlox muscoides Nutt. [61,106,138]
= Phlox hoodii ssp. muscoides (Nutt.) Wherry [57,70]
NRCS PLANT CODE :
The scientific name of Hood's phlox is Phlox hoodii Richards. (Polemoniaceae) . Many subspecies are recognized. Throughout this review, subspecies will be identified using scientific names.
Phlox hoodii ssp. canescens (Torr. & Gray) Wherry [61,70,72,88], woolly phlox, carpet phlox
Phlox hoodii ssp. glabrata (E. Nels.) Wherry [57,70], carpet phlox
Phlox hoodii ssp. hoodii [57,70], Hood's phlox, spiny phlox
Phlox hoodii ssp. lantana (Piper) Munz [70,71], carpet phlox
Phlox hoodii ssp. muscoides (Nutt.) Wherry [57,70], moss phlox, musk phlox
Phlox hoodii ssp. viscidula (Wherry) Wherry [57,70], carpet phlox
FEDERAL LEGAL STATUS:
No special status
Information on state-level protected status of plants in the United States is available at Plants Database.
Plants Database provides a distributional map of Hood's phlox and the following subspecies: Phlox hoodii ssp. canescens, P. h. ssp. glabrata, P. h. ssp. hoodii, P. h. ssp. lantana, P. h. ssp. muscoides, P. h. ssp. viscidula. For more detailed descriptions of the distributions of P. h. ssp. canescens and P. h. ssp. muscoides, see [37,61].ECOSYSTEMS :
prairie Junegrass (Koeleria macrantha)-Hood's phlox association, also known as the Koelerietum Phloxetosum association on glacial till in Glacier County 
|© Paul Slichter|
Aboveground description: Hood's phlox is a small, low-growing, mat-forming, perennial [62,68]. There is considerable variability in botanical characteristics, which is only partially reduced by the recognition of subspecies. Descriptions of compact matted and loosely caespitose growth forms are described [5,55]. The woody root crown or caudex produces multiple branches [5,138]. Plants are typically hairy and measure between 2 and 12 inches (5-30 cm) across and less than 5 inches (13 cm) tall [4,68,71,79,94,95]. Plants monitored for 8 years in southwestern North Dakota averaged 1.8 inches (4.6 cm) tall. Maximum and minimum heights were 2.4 inches (6.0 cm) and 1.2 inches (3.0 cm), respectively . Branches are crowded with nodes and dense with leaves [18,67,94,95]. Hood's phlox is a stress-tolerant species with slow leaf turnover . Early spring growth is rapid, and plants normally mature before associated vegetation grows to an "appreciable height" [22,54].
Leaves occur opposite one another and are described as woolly or loosely pubescent, with long tangled or cobwebby hairs [5,18,67,68,137]. Leaves are narrow, firm, pungent, and needle-like with sharp points; often the mid-rib is thickened [4,62,79]. Degree of leaf overlap varies, and leaves are typically ascending [35,55,137]. Leaves normally range from 0.1 to 0.5 inch (3-13 mm) long and less than 1 mm wide at the midpoint [37,55,57,79,137]. Old leaves are persistent . Flowers are most often solitary and appear at the ends of branches [5,67,94]. Petals are 5 lobed and range from white to pale blue, purple, or pink [35,57,62]. Petal lobes are typically 0.16 to 0.28 inch (4-7 mm) long, and the flower tube measures 0.24 to 0.47 inch (6-12 mm) long [18,62]. Seeds are normally 0.08 to 0.1 inch (2-3 mm) long .
Belowground description: Hood's phlox produces coarse woody taproots [35,57,62,95]. Roots excavated from a sagebrush-dominated site in western Colorado tested positive for mycorrhizal associations .
Taproots penetrate deeply if soil depth permits, and lateral roots are short. Maximum root penetration was 36 inches (91 cm) in a pristine big sagebrush/mixed grass community in southern Idaho . In mixed prairie of southwestern Saskatchewan, taproots reached depths of 12 to 37 inches (30-95 cm). Root diameters were 1 to 5 mm near the soil surface but decreased to approximately 0.5 mm at 8 to 10 inch (20-25 cm) soil depths. Lateral roots occurred singly or in groups of 2 to 5 at soil depths below 2 to 4 inches (5-10 cm). Lateral roots had diameters of 0.3 to 0.5 mm and were short (≤2 cm). Occasionally plants produced 1 to 2 large secondary taproots that penetrated as deep as the primary taproot. Penetration depths were greatest in well-developed soils on level sites or on lower slope positions. The average maximum root depths were 34 inches (86 cm) and 12 inches (30 cm) on lower and upper slopes, respectively. In shallow soils, roots did not penetrate beyond 12 inches (30 cm). In sandy soils, roots typically penetrated less than 16 inches (41 cm), but lateral roots were more dense and widely spread than those in fine textured soils .
The wide range in plant, leaf, and flower size and form is reduced slightly with the recognition of Hood's phlox subspecies. Often subspecies descriptions are made in relation to another subspecies. For more information on distinguishing subspecies, see [37,55,57,61,62,71,88,94,100,137,138].RAUNKIAER  LIFE FORM:
Pollination: Most phlox (Phlox spp.) are pollinated by Lepidoptera species. Phlox hoodii ssp. muscoides is pollinated by long-tongued bees .
Breeding system: The presence of insect pollinators suggests that cross pollination may predominate.
Seed production: Information regarding Hood's phlox seed production is scant. Stevens  reported that 50 seeds/plant were produced by mature, average-sized plants growing in a "low competition" area in North Dakota. Seed was collected in seed traps in harvested singleleaf pinyon-Utah juniper (Pinus monophylla-Juniperus osteosperma) stands in west-central Nevada. Abundance of seeds captured was not reported, and seeds were only collected from western aspects, although there were traps on north and south slopes as well .
Seed dispersal: Hood's phlox seed is small  and could easily be transported by wind. Small mammals may also disperse Hood's phlox seed .
Seed banking: Several studies indicate that Hood's phlox produces a seed bank; however, information regarding seed longevity and persistence in the soil is lacking. Hood's phlox emerged from a bluebunch wheatgrass-blue grama (Pseudoroegneria spicata-Bouteloua gracilis) community after treatment with glyphosate herbicide that killed all plants, indicating emergence from soil-stored seed .
Hood's phlox emerged from soil collected in a Wyoming big sagebrush (Artemisia tridentata ssp. wyomingensis) community. Soil was collected from 4 sites, each with an undisturbed area and an adjacent area ploughed and seeded to crested wheatgrass (Agropyron cristatum) 20 years before the study. Seeded sites 1 and 2 were relatively stable, and seeded sites 3 and 4 were being colonized by native vegetation. Hood's phlox coverage and seedling emergence were greatest in undisturbed sites. The relative cover of and relative seedling emergence of Hood's phlox on seeded and undisturbed sites is summarized below :
|Relative cover (%)¹||Relative seedling emergence (%)²|
A low number of Hood's phlox seedlings emerged from soil collected from 1-year-old burned and unburned sites in Power County, southeastern Idaho. The fire burned in vegetation dominated by threetip sagebrush (Artemisia tripartita) and mountain big sagebrush (A. tridentata spp. vaseyana). Fire characteristics were not provided. Hood's phlox cover was 0.75% on unburned sites and 1.43% on burned sites. The relative density of Hood's phlox seedlings was 0.004% from unburned soil and 0.006% from burned soil. The researcher indicated that Hood's phlox recovered on burned sites primarily through vegetative means .
Hood's phlox did not emerge from soil collected from burned or unburned sites in sheep fescue-alpine bluegrass (Festuca ovina-Poa alpina), big sagebrush/Idaho fescue (A. tridentata/F. idahoensis), or bluebunch wheatgrass-Sandberg bluegrass-needle-and-thread grass (P. secunda-Hesperostipa comata) habitats in Yellowstone National Park, although it was present in the aboveground vegetation of all sites .
Germination: No information is available on this topic.
Seedling establishment/growth: Information on Hood's phlox seedling establishment is limited. However, the following studies suggest that deep litter and/or dense shading restrict seedling establishment. Hood's phlox was restricted to interspaces in singleleaf pinyon-Utah juniper stands in Nevada . Hood's phlox seedling density was 0.7/m² in 1984 and 1.4/m² in 1985 in a grazed bluebunch wheatgrass-blue grama range in Norris, Montana. Seedling densities were equal on the two study sites, although one was in poorer condition .
Vegetative regeneration: Hood's phlox regenerates vegetatively following fire or other aboveground damage and is common in early postfire communities [3,31,102]. Hood's phlox coverage was greater on 1-year-old burned sites than on unburned sites in Power County, southeastern Idaho, and regeneration was primarily vegetative .SITE CHARACTERISTICS:
Specific characteristics are described for several areas where Hood's phlox is common. Near Saskatoon, Saskatchewan, Hood's phlox importance values were greatest on the upper and middle positions on eastern to southern slopes. From May to September soil temperatures on upper and middle southern slopes averaged 81 °F (27 °C), and average soil moisture content was 7.9% and 5.3%, respectively. Hood's phlox importance changed dramatically with relatively minor changes in aspect and position .
In Eagle, Alaska, Hood's phlox occurred in fringed sagebrush (Artemisia frigida)/bluebunch wheatgrass steppe vegetation but not in forested vegetation dominated by quaking aspen (Populus tremuloides), balsam poplar (P. balsamifera), and white spruce (Picea glauca). Environmental conditions were different in the 2 habitats. Soil moisture was lower and soil temperature was higher in steppe vegetation than in the forests. Steppe vegetation received 93.9% full sun and forests received 57%. Litter cover was 5% in steppe vegetation and 79% in forests .
Hood's phlox was common on glacial moraines in northwestern Montana's Upper Blackfoot Valley and reached its greatest frequency on the upper part of southern slopes. Summer soil moisture content averaged 11% on upper slopes, less than that of lower slope positions. Temperatures were higher and temperature fluctuations were greatest on southern slopes .
Hood's phlox is most typical in sagebrush habitats. Characteristics of some of these habitats are summarized below.
|Rangeland cover type||Elevation
|Black sagebrush |
|middle elevations||8-12 inches, most common||coarse textured, dry soils |
|3,000-9,000||8-16 inches||shallow soils; normally 12-20 inches to clay or bedrock |
|700-4,000||8-16 inches||shallow soils; typically < 9.8 inches to basalt |
|Threetip sagebrush||4,000-9,000||12-16 inches; cool, moderately moist sites||intermediate between big sagebrush and low and black sagebrush types |
|Wyoming big sagebrush||----||7-12 inches; ~40% in growing season||moderate to fairly shallow, low in organic matter, stony, often over hardpan or parent material |
Climate: Hood's phlox primarily occupies sites with continental climates. Conditions are typically dry, and a wide range of temperatures are possible. In North Dakota, Hood's phlox occurs in the west where arid conditions prevail . Parker  reports that Hood's phlox occupies sites that receive 15 to 20 inches (380-510 mm) of annual precipitation. However, Hood's phlox occurs in steppe vegetation in Eagle, Alaska, where annual precipitation averages 12.1 inches (308 mm) and average January and July temperatures are -9.4 °F (-23 °C) and 59 °F (15 °C), respectively . In areas near Saskatoon, Saskatchewan, where Hood's phlox occurs, snow is typical from November to March and contributes 30% to the total annual precipitation. Summer temperatures over 100 °F (38 °C) and winter lows of -40 °F (-40 °C) have been recorded for this area . In the Laramie Basin of Wyoming, precipitation averages 11.2 inches (284 mm), and January and July temperatures average 22.4 °F (-5.3 °C) and 64 °F (17.8 °C) . Hood's phlox is sparsely distributed on the Dickinson Experimental Station in southwestern North Dakota, where winters are long and cold, and summers are short and hot. Based on a 70-year record, annual precipitation averaged 15.5 inches (394 mm), and June temperatures averaged 61.4 °F (16.3 °C) .
A number of studies indicate that Hood's phlox is restricted to sites with early snow melt. Hood's phlox was rarer on sites with late snow melt dates than on sites with early melting dates on the Bangtail Mesa near Bozeman, Montana . Hood's phlox was common (presence 56%) on sites with a snow melt date of 15 May in southwestern Montana; Hood's phlox presence decreased as snow cover remained longer. Presence was 27% on sites with a 1 June melt date, and Hood's phlox was absent from sites with melt date of 15 June or later . In central Wyoming's Owl Creek range, Hood's phlox was present on windblown sites in threetip sagebrush-dominated sites but was absent from sites where deep snow drifts were common .
Elevation: Hood's phlox is common at middle and high elevations throughout its range. Narrower elevational ranges by state and variety are provided below:
|State/region||Variety, if applicable||Elevation in feet|
|California||P. h. ssp. canescens||4,500-8,900 [61,94]|
|P. h. ssp. lantana||4,000-6,000 |
|P. h. ssp. muscoides||4,600-8,900 |
|New Mexico||P. h. ssp. canescens||5,000-7,000 |
|P. h. ssp. lantana||6,500-8,000|
|P. h. ssp. muscoides||5,600-8,000 |
|Uinta Basin, Utah||4,800-8,400|
|P. h. ssp. muscoides||~7,100 |
|P. h. ssp. canescens||4,790-10,700|
|P. h. ssp. muscoides||4,590-6,910 |
Soils: Hood's phlox persists on a variety of soil types; however, it commonly occurs on dry, coarse textured soils. In the northern Great Plains and in Utah, Hood's phlox occurs on gravelly, rocky, or sandy soils [57,95]. In grasslands of southwestern Saskatchewan, Hood's phlox was most closely associated with clay and loam soils and was present on fine sandy loams, loams, and clay loams . In steppe vegetation of central Montana, Hood's phlox cover and constancy were "consistently" higher on fine-textured soils, and Hood's phlox showed little preference for position along a gradient of 0.4 to 4 inches (1-10 cm) of water storage capacity . Hood's phlox was most common on windward exposures where soil moisture was lowest in sagebrush steppe vegetation at Wyoming's Stratton Sagebrush Hydrology Study Area . In Utah, Hood's phlox coverage was significantly greater (p≤0.01) on crest than mid-slope or base sites. Crest sites were the most xeric and had the shallowest soils, which averaged 8 inches (20 cm) deep. Clay content was significantly lower and sand and exposed rock were significantly greater on crest than mid-slope or base positions .SUCCESSIONAL STATUS:
Early seral: Hood's phlox is considered a pioneer species in dryland succession in south-central Utah's high plateaus. The Hood's phlox root system tolerates fluctuating soil levels allowing it to occur on dunes formed when sand accumulates around crevice plants and along sandstone ledges . Hood's phlox occurred on stabilized blowouts and stabilized dunes but was absent from unstabilized dunes in southern Saskatchewan. Unstabilized dunes were characterized by active erosion and/or deposition. Stabilized blowouts were round depressions that showed evidence of past erosion but no current erosion. Stabilized dunes showed no signs of recent erosion. The pH was higher, sand content greater, and organic matter lower on unstabilized dunes than on stabilized blowouts or dunes .
Late seral: A number of stable, late-seral, and/or climax communities provide Hood's phlox habitat. In Glacier County, Montana, the prairie Junegrass-Hood's phlox association is considered a "naturally occurring topoedaphic climax on moraine summits" . In other parts of western Montana, Hood's phlox is common in Idaho fescue-bluebunch wheatgrass communities that are considered late seral . In southeastern Idaho's Craters of the Moon National Monument, Hood's phlox is a dominant forb in stable, undisturbed islands of low sagebrush/Idaho fescue-Thurber needlegrass (Achnatherum thurberianum) that were ungrazed, unburned and considered "pristine" .
Response to grazing: Many suggest that Hood's phlox increases with domestic grazing or deteriorating range condition [68,78,83,95]; however, the grazing response is variable. For more information, see Other Management Considerations.
Response to other disturbances: Hood's phlox is typically present in early postfire communities [3,31,102] but is normally absent from severely disturbed mining areas.
Hood's phlox was present on windblown sites in threetip sagebrush vegetation in central Wyoming's Owl Creek range but was absent from mining test trenches dug almost 35 years earlier. The researcher noted that disturbed soil and/or snow pack levels may have affected Hood's phlox's absence . After studying disturbed and undisturbed sites in western Colorado's Piceance Basin where oil shale extraction occurs, researchers suggested that the loss of soil mycorrhizae may affect postdisturbance recovery. Hood's phlox, which has mycorrhizal associations, was absent from disturbed but present on undisturbed sites. Disturbed sites were abandoned roads that had been ripped to a depth of 18 inches (46 cm) three to four years prior to their study. Ninety-nine percent of the cover on undisturbed sites and less than 1% of the cover on disturbed sites was from species with mycorrhizal associations .
Degree of disturbance affected Hood's phlox recovery in basin big sagebrush/mixed grass habitats in Colorado's Piceance Basin. Soil disturbance treatments were: 1) minimal disturbance to topsoil (A and B horizons), 2) "ripped" topsoil to 12-inch (30 cm) depths, 3) removal of top- and subsoil (A to C horizons) to 3 feet (1 m) that were mixed and then put back, 4) removal of top- and subsoil in 2 sections to 3 feet (1 m) that were replaced in reverse order. Hood's phlox was absent from sites treated with methods 3 and 4. Relative Hood's phlox cover in successive years following disturbance treatments 1 and 2 are provided below .
|Treatment 1||Treatment 2|
|Years since disturbance||1||4||5||6||1||4||5||6|
|Relative Hood's phlox coverage (%)||6.34||3.81||5.92||8.33||1.14||1.44||3.74||7.52|
|State/region||Variety, if applicable||Flowering dates|
|California||P. h. ssp. canescens||May-July|
|P. h. ssp. lantana||May-June |
|P. h. ssp. muscoides||May-June |
|New Mexico||P. h. ssp. canescens||May-July |
|North Dakota||April-May |
|South Dakota||early spring |
|Utah, northeastern||April-July |
|Utah, Uinta Basin||P. h. ssp. hoodii||March-May|
|P. h. ssp. muscoides||May-June |
|Great Plains||April-July |
|Intermountain West||P. h. ssp. hoodii||April-June|
|P. h. ssp. muscoides||May-June |
|Pacific Northwest||April-June |
In central Montana, Hood's phlox growth begins in early spring . In southwestern North Dakota, seasonal development of Hood's phlox was monitored for 8 years. The earliest bloom date was 28 April, and the average earliest bloom date was 24 May. Plants attained 93.3% of total growth in May and 100% of their growth by June . Hood's phlox plants on the Carey Kipuka in southern Idaho are fully grown between 25 May and 5 June .On an experimental farm in Swift Current, Saskatchewan, Hood's phlox flowering dates were recorded for 13 years. The earliest Hood's phlox was found in flower on 30 April, and the latest date of 1st flowering was 11 May. The latest date Hood's phlox was found in flower was 7 July. The average flowering period was 36 days . In southern Saskatchewan and southeastern Alberta, Hood's phlox growth begins in the 1st or 2nd week in April. Flowers are common in late April; seed is typically ripe by mid-June. If soil moisture is "sufficient," Hood's phlox may flower again in August . A second flowering period is also noted following summer rains in Arizona .
Fire regimes: Western sagebrush (Artemisia spp.) and grassland communities are common Hood's phlox habitat. Average fire frequency in sagebrush/grassland vegetation is estimated at 32 to 70 years . However, in the black sagebrush range type, wildfire is considered relatively rare due to the low fuel continuity . Low sagebrush vegetation is also thought to burn less often than big sagebrush types because fuel cover is sparse . In many sagebrush vegetation types including Wyoming big sagebrush- and stiff sagebrush-dominated communities, nonnative cheatgrass (Bromus tectorum) is an important associated species. Cheatgrass invasion tends to increase fine fuel loading and continuity [126,130], and has likely increased fire frequency beyond presettlement intervals [99,140].
The following table provides fire return intervals for plant communities and ecosystems where Hood's phlox 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)|
|bluestem prairie||Andropogon gerardii var. gerardii-Schizachyrium scoparium||<10 [76,97]|
|Nebraska sandhills prairie||Andropogon gerardii var. paucipilus-Schizachyrium scoparium||<10 |
|silver sagebrush steppe||Artemisia cana||5-45 [60,101,141]|
|sagebrush steppe||Artemisia tridentata/Pseudoroegneria spicata||20-70 |
|basin big sagebrush||Artemisia tridentata var. tridentata||12-43 |
|mountain big sagebrush||Artemisia tridentata var. vaseyana||15-40 [9,25,89]|
|Wyoming big sagebrush||Artemisia tridentata var. wyomingensis||10-70 (x=40) [134,144]|
|saltbush-greasewood||Atriplex confertifolia-Sarcobatus vermiculatus||<35 to <100 |
|plains grasslands||Bouteloua spp.||<35 [97,141]|
|blue grama-needle-and-thread grass-western wheatgrass||Bouteloua gracilis-Hesperostipa comata-Pascopyrum smithii||<35 [97,108,141]|
|cheatgrass||Bromus tectorum||<10 [99,140]|
|curlleaf mountain-mahogany*||Cercocarpus ledifolius||13-1,000 [11,112]|
|mountain-mahogany-Gambel oak scrub||Cercocarpus ledifolius-Quercus gambelii||<35 to <100|
|western juniper||Juniperus occidentalis||20-70|
|Rocky Mountain juniper||Juniperus scopulorum||<35 |
|wheatgrass plains grasslands||Pascopyrum smithii||<5-47+ [97,101,141]|
|pinyon-juniper||Pinus-Juniperus spp.||<35 |
|Rocky Mountain bristlecone pine||P. aristata||9-55 [42,43]|
|Colorado pinyon||Pinus edulis||10-400+ [51,56,73,97]|
|interior ponderosa pine*||Pinus ponderosa var. scopulorum||2-30 [8,13,81]|
|Arizona pine||Pinus ponderosa var. arizonica||2-15 [13,34,114]|
|mountain grasslands||Pseudoroegneria spicata||3-40 (x=10) [7,8]|
|Rocky Mountain Douglas-fir*||Pseudotsuga menziesii var. glauca||25-100 [8,9,10]|
|little bluestem-grama prairie||Schizachyrium scoparium-Bouteloua spp.||<35 |
Hood's phlox was present in the 1st postfire year and increased in coverage in the 2nd postfire year following a prescribed fire in a Wyoming big sagebrush/bluebunch wheatgrass habitat near Shoshone, Idaho. The fire burned in late September when relative humidity was 19% to 36%, winds were 3 to 25 miles (4.8-40 km)/hour, and air temperatures ranged from 64 to 86 °F (18-30 °C). Hood's phlox coverage was 0.4% and 2% in the 1st and 2nd postfire years, respectively. There were no prefire or unburned comparisons . At the Idaho National Engineering and Environmental Laboratory in southeastern Idaho, Hood's phlox was the dominant forb on 15-year-old burned and unburned sites near the Arco Highway. Just descriptive results were reported since the sampling intensity was too weak for statistical analyses .
While decreases in Hood's phlox abundance following fire are common, they are not without exception. In southeastern Idaho's, Power County, Hood's phlox coverage on 1-year-old burned sites was almost double that of unburned sites. The fire burned in vegetation dominated by threetip and mountain big sagebrush, but fire characteristics were not described. Hood's phlox cover was 0.75% on unburned and 1.43% on burned sites. Soils collected from unburned and burned sites had relative Hood's phlox seedling densities of 0.004% and 0.006%, respectively. The researcher reported that Hood's phlox recovery was primarily vegetative .
Hood's phlox was not sampled on control or prefire plots before a late September prescribed fire in Wyoming big sagebrush habitats of southeastern Oregon's Hart Mountain Antelope Refuge. However, percent frequency on control plots was 0.4 ± 0.4 (sx) and 0.2 ± 0.2 on burned plots in the 1st postfire year. Hood's phlox sprouted "weakly" from the base and was classified as a fire "avoider or endurer." At the time of burning, temperatures were 66 to 82 °F (19-28 °C), relative humidity ranged from 17% to 24%, and wind speeds were 4 to 6 miles (6.4-9.7 km)/hour. Flame heights ranged from 6.6 to 12 feet (2-3.7 m), and flame lengths were 6.6 to 26 feet (2-7.8 m). The fire spread rate was 15 to 39 feet (4.6-12 m)/minute, and residence time ranged from 0.6 to 2.6 minutes .
Density of Hood's phlox was greater on control plots than spring, summer, or fall burned sites in a central Saskatchewan rough fescue prairie. There were 1.7 Hood's phlox stems/m² on control plots and 1.3, 0.7, and 0.7 stems/m² on spring, summer, and fall burned sites, respectively, in the 2nd postfire growing season. Fires burned when air temperatures were 50 to 79 °F (10-26 °C), relative humidity was 35% to 50%, and wind speeds were 5.6 to 8.9 feet (2.5-4 m)/second. Air temperature and relative humidity were highest during the summer fire and lowest for the spring fire . For a complete description of the fires and their effects, see Seasonal fires in Saskatchewan rough fescue prairie.
Hood's phlox was absent from the most severely burned sites following a December fire in a rough fescue grassland in southwestern Alberta. Hood's phlox did not occur on sampled sections within the interior of the burned area but did occur on sites less severely burned in a perimeter fire. The fire was described by others (Tymstra 1998, as cited by ) as extremely hot. Winds were 19 to 25 miles (30-40 km)/hour with gusts of up to 43 miles (70 km)/hour. Mid-day temperature was 55 °F (13 °C), and relative humidity was 17% on the day of the fire. Head fire intensity was an estimated 10,000 to 20,000 kW/m², and the spread rate was approximately 6 miles (10 km)/hour. In adjacent unburned sites, litter content was 900 kg/ha. Hood's phlox canopy coverage was 0.1% and 0.4% in the perimeter burn compared with 0.7% and 1.2% on control sites sampled in the 1st and 2nd postfire years, respectively .
Plot size affected the magnitude of Hood's phlox increases and decreases on burned and unburned sites before and after a prescribed fire in a threetip sagebrush-dominated community in southern Idaho. The fire burned on 15 September when the temperature was 70 °F (21 °C), relative humidity was 14%, and winds were 5 to 8 miles (8-10 km)/hour. Live sagebrush moisture was 92%, and soil moisture was 4%. Percent frequency and dry weight production of Hood's phlox were lower on burned than unburned sites after the fire, but prefire frequencies were lower on burned than control sites as well. Study results are summarized below .
|Hood's phlox frequency (%)||Burned||Control|
|Plot size (cm)||25×25||25×50||50×50||25×25||25×50||50×50|
|2 years before fire||5||8.8||11.3||----||----||----|
|1 year before fire||3.8||11.3||18.8||17.5||28.8||37.5|
|1 year after fire||2.5||2.5||2.5||12.5||30.0||52.5|
|3 years after fire||6.3||12.5||23.8||17.5||26.3||35.0|
|Time since fire (years)||prefire||1||prefire||1|
|Hood's phlox dry weight (lbs/acre)||49.2||14.0||51.1||90.0|
FIRE MANAGEMENT CONSIDERATIONS:
Based on the available information on Hood's phlox and fire, recovery of Hood's phlox is likely following most fires. However, the lack of information on the response of Hood's phlox to successive fires makes it difficult to predict its ability to persist in areas dominated by cheatgrass with high fire frequencies.
Postfire management may impact Hood's phlox recovery. Low Hood's phlox cover was reported on 3-year-old burned sites in pinyon-juniper (Pinus-Juniperus spp.) and big sagebrush communities that were drill or aerial seeded following a wildfire in central Utah. Coverage of Hood's phlox was 0 on one burned and seeded site and 0.4% on another. Sites burned in July, but fire characteristics were not reported. Seeded species included wheatgrasses (Elymus spp.), sweet clover (Melilotus spp.), and alfalfa (Medicago spp.) among others .
Domestic sheep: Use of Hood's phlox by domestic sheep is occasional. Primarily flowers are consumed , and some researchers indicate that sheep "relish" Hood's phlox flowers .
Deer: Several studies report utilization of Hood's phlox by mule deer although it rarely contributes much to their overall diet. Hood's phlox was an important November food source for mule deer in Fergus County, Montana . In Montana's Gallatin Canyon, mule deer use of Hood's phlox was light in the winter. Its use was not observed in January or February, but 2% of March feeding observations were on Hood's phlox .
Researchers observed tame mule deer feeding on Hood's phlox in the early spring in a Colorado pinyon-Utah juniper/mixed shrub winter range in Colorado's Piceance Basin. Hood's phlox made up a high of 3% of observations made in April and a high of 4% in March over the course of 2 years on 2 sites. Utilization of Hood's phlox was little to none from October through January . Feeding observations on a bighorn sheep winter range in Idaho's East Fork of the Salmon River revealed use by mule deer but not by bighorn sheep. Hood's phlox made up 2.9% of the total instances of mule deer use in February in Wyoming big sagebrush/bluebunch wheatgrass vegetation. In big sagebrush/bluebunch wheatgrass-Sandberg bluegrass vegetation, Hood's phlox use was 5.3% in January, 2.5% in February, 0.3% in March, and 0.2% in April .
Elk: Hood's phlox abundance on protected sites exceeded that on grazed sites, although differences were not statistically (p>0.05) significant on the northern winter range in Yellowstone National Park. Elk were the primary grazers in the area. The researcher suggested that elk may have utilized Hood's phlox when it was actively growing .
Pronghorn: Hood's phlox is common in pronghorn habitats, but use of Hood's phlox is limited. On rangelands in Yellowstone National Park that are used year round by pronghorn, Hood's phlox was common . Pronghorn in Wyoming's Red Desert used big sagebrush habitats extensively. The density of half-shrubs including Hood's phlox were significantly (p=0.002) greater on high use than on low use winter sites. Feeding observations and fecal analyses revealed a low level of forbs in pronghorn diets, but species were not identified .
In Petroleum County, Montana, researchers observed pronghorn feeding on Hood's phlox 0.9% of the time. Use of Hood's phlox was restricted to the spring season . One percent of the rumen contents of pronghorn collected in the summer from sagebrush/grasslands in the Cypress Hills of Saskatchewan was Hood's phlox. None of the stomachs from pronghorn collected in the Matador Hills contained Hood's phlox and none of the stomachs collected in fall, winter, or spring from the Cypress Hills contained Hood's phlox. Pronghorn populations were fairly large in Cypress Hills .
Bighorn sheep: Utilization of Hood's phlox by bighorn sheep is low. Hood's phlox was less than 0.5% by volume of the contents of 15 bighorn sheep stomachs collected in October and November in the Sun River area of west-central Montana .
Small mammals: Hood's phlox seed and leaves are consumed by a variety of small mammals. Mountain cottontail and bushy-tailed woodrat diets were evaluated from feces collected near the Idaho National Engineering and Environmental Laboratory in south-central Idaho. Hood's phlox was not detected in bushy-tailed woodrat feces but made up 1.6% of the relative density of mountain cottontail feces . In South Dakota's Buffalo Gap National Grassland, black-tailed prairie dogs fed on Hood's phlox in the winter. At most other times of the year, however, Hood's phlox was avoided. Decreased water availability and stressful winter feeding conditions were thought to contribute to diet changes that were evaluated through stomach analyses .
Controlled food preference studies indicated that Hood's phlox seeds are consumed by deer mice and Great Basin pocket mice in eastern Washington. Mice were presented a known quantity of Hood's phlox seed and seed capsules. All of the seed capsules presented on the surface of the sand were consumed by both species. All of the seed presented to Great Basin pocket mice was consumed. Deer mice consumed all but about 15% .
Birds: Numerous bird species reside in or visit Hood's phlox habitats, but information on the specific use of Hood's phlox by birds is lacking. Many bird species were found in mixed grasslands in Wyoming's Laramie Basin during a 3 year census. Mountain plovers, horned larks, and McCown longspurs utilized the area for breeding. Many other birds visited the area, including turkey vultures, red-tailed hawks, ferruginous hawks, marsh hawks, sparrow hawks, killdeer, California gulls, cliff swallows, barn swallows, rock wrens, common nighthawks, western meadow larks, lark buntings, and vesper sparrows. Specific utilization of Hood's phlox was not reported .
Hood's phlox was common in big sagebrush habitats utilized by sage-grouse in Jackson County, Colorado, for nesting, strutting, and spring and summer feeding. Feeding observations, however, were not species specific . Hood's phlox was considered a nonpalatable forb during a study of sage-grouse in southeastern Alberta . In the Strawberry Valley of north-central Utah, Hood's phlox coverage was significantly greater (p<0.05) in sage-grouse nesting areas than in brooding habitats or adult use areas .
Palatability/nutritional value: The palatability and forage value of Hood's phlox are considered low [92,95]. Dittberner and Olson  rate Hood's phlox palatability as poor for cattle and horses. Palatability ranges from poor to fair for domestic sheep and elk, poor to good for pronghorn, mule deer, and white-tailed deer, fair for small mammals, poor to fair for game birds, and fair for nongame birds in North Dakota, Montana, Wyoming, Utah, and Colorado.
Cover value: Hood's phlox grows very low to the ground and likely provides cover for only the smallest wildlife species and for insects.VALUE FOR REHABILITATION OF DISTURBED SITES:
Dakotas: Hood's phlox was absent from protected sites but had a density of 7.3/m² after 39 years and 19.3/m² after 40 years of cattle grazing in a blue grama-needle-and-thread grass-threadleaf sedge community in southwestern North Dakota. Protected sites had taller perennial forbs, lower soil temperatures, and lower soil bulk density than grazed sites. Grazed sites had more unpalatable forbs or forbs too short to be grazed such as Hood's phlox. Researchers considered both grazed and ungrazed sites to be in near climax condition . In the northern Great Plains, Hood's phlox coverage was generally greatest under heavy cattle stocking rates on summer ranges, and under intermediate stocking rates on winter ranges, when various stocking rates and seasons of use were compared .
Idaho: The frequency and density of Hood's phlox decreased after 15 years of protection from livestock grazing in Wyoming big sagebrush/bottlebrush squirreltail vegetation in southeastern Idaho . Hood's phlox increases were greatest on spring grazed sites at the U.S. Sheep Experimental Station near Dubois, Idaho. On sites protected from domestic sheep grazing for 14 years, Hood's phlox increased only slightly. On fall grazed sites, Hood's phlox showed only minor changes .
Montana: Cover of Hood's phlox was typically greater on heavily grazed than protected areas of Idaho fescue-bluebunch wheatgrass communities in Montana's Beaverhead National Forest. Grazed areas were open to cattle grazing for at least 50 years, and exclosures were protected for 15 to 18 years. Sites 1H, 2H, and 4H received heavy use in June and July; sites 5M and 3L received moderate and light use, respectively, from June through October. Percent Hood's phlox cover is provided below for grazed and adjacent protected areas .
In western Montana, paired grassland plots receiving different levels of use were compared. Cattle were the predominant grazers. Use by sheep was rare, but use by deer and elk was likely. Hood's phlox cover was typically greater on grazed than protected sites, and generally increased with increased use. However, not all sites followed this trend. The percent cover of Hood's phlox is provided below for various communities grazed at different intensities .
|Vegetation type||Grazing level||Significance (p value)|
|Needle-and-thread grass-blue grama||----||2.5||0.8||----||<0.1|
|bluebunch wheatgrass-blue grama||1.0||----||----||0.8||ns|
|bluebunch wheatgrass-blue grama||----||----||1.8||0.2||<0.01|
|bluebunch wheatgrass-western wheatgrass (Pascopyrum smithii)||7.4||----||12.8||----||<0.05|
|rough fescue-bluebunch wheatgrass||----||1.4||----||8.5||<0.01|
|rough fescue-bluebunch wheatgrass||0.1||----||1.3||----||ns|
|Idaho fescue-western wheatgrass||2.0||----||1.6||----||ns|
|Idaho fescue-bluebunch wheatgrass||0.8||----||2.9||----||<0.1|
|Idaho fescue-bluebunch wheatgrass||5.9||----||12.8||----||<0.01|
|Idaho fescue-bluebunch wheatgrass||----||10.4||10.6||----||ns|
Nevada: Coverage of Hood's phlox more than doubled following 30 years of grazing protection in an "eroded" big sagebrush/Sandberg bluegrass community in northern Nevada. Since the 1860s, sheep, cattle, and horses had grazed the area. The researcher noted that precipitation levels in May and June were 0.82 inch (2.1 cm) during the 1st year of protection when baseline measurements were made and 4.2 inches in 1970 when measurements were made on protected sites .
Wyoming: Hood's phlox basal cover was relatively unaffected by grazing in threetip sagebrush communities in southeastern Wyoming's Laramie range. Basal coverage inside the exclosure was 2.1% when it was constructed and 2.3% thirteen years after construction. Outside the exclosure, basal coverage was 6.8% in the year of construction and 6.7% thirteen years after .
Frequency of Hood's phlox was greater on grazed (76%) than on ungrazed relict sites (54%) in Sweetwater County, Wyoming. Relict sites were not grazed by any herbivore other than rodents in "historic time." Domestic livestock grazers and patterns were not reported .
Alberta and Saskatchewan, Canada: The basal area of Hood's phlox was significantly (p<0.01) greater after cattle grazing at a rate of 40 acres/head for 6 years than before grazing in blue grama- and needle-and-thread grass-dominated grassland in southern Alberta and southwestern Saskatchewan. Differences in Hood's phlox basal area between pre- and postgrazing at rates of 20 and 30 acres/head were not significantly different . Basal area of Hood's phlox was greater on lightly grazed areas than on areas protected for 33 years on a needle-and-thread grass-blue grama prairie in southeastern Alberta, though differences were not significant .
Hood's phlox basal area increased significantly (p<0.01) on continuously grazed blue grama prairie in southeastern Alberta and decreased slightly when grazed in a rotation pattern. However, density of Hood's phlox increased significantly under both grazing systems. Continuous grazing lasted 6 months. The rotational grazing pattern was 1.5 months use in the spring and 1.5 months use in the fall for 1 year and 3 months of summer use the next year. Stocking rates were 10 yearling steers/300 acres .
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