General: Flax Family (Linaceae). Linum perenne is introduced from Eurasia. Linum lewisii is a comparable U.S. native plant (figure 1). In general, flax is an annual or short-lived, semi-evergreen perennial forb, sometimes semi-woody at base with attractive flowers ranging from white to blue to yellow to red in color. Common in the western United States, blue flax is considered a woody subshrub in the PLANTS database (USDA, NRCS 2000). According to Cronquist et al. (1997), “the only significant difference between Linum lewisii and the Eurasian Linum perenne appears to be that the former is homostylic, and the latter heterostylic.”

Flax plants have many narrow, small, alternate (rarely opposite), simple and entire leaves that are sessile (lacking stalks) on the stems. The perfect and regular, generally showy flowers are borne in racemes or cymes. The sepals, petals, and stamens are five, the fruit a capsule, and the seeds in most species are mucilaginous when wet.

Prairie flax

(key to state/province abbreviations)
UNITED STATES

AK	AZ	AR	CA	CO	ID	KS	LA	MI	MN
MT	NE	NV	NM	ND	OK	OR	SD	TX	UT
WA	WV	WY

CANADA

AB

BC

MB

NT

NU

ON

SK

YK

MEXICO

N.L.

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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):

BLM PHYSIOGRAPHIC REGIONS [18]:

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

Lewis flax is widely distributed throughout North America. Its northern limit occurs in Alaska. Its distribution extends east to Ontario, Michigan, Nebraska, Kansas, Arkansas, and Louisiana. The southern limit occurs in northern Mexico [4,59,90,91]. Disjunct populations of Lewis flax occur in West Virginia [122]. Plants Database provides a distributional map of Lewis flax.

Linum lewisii Pursh:
China (Asia)
Mexico (Mesoamerica)
United States (North America)

Note: This information is based on publications available through Tropicos and may not represent the entire distribution. Tropicos does not categorize distributions as native or non-native.

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

United States

Origin: Unknown/Undetermined

Regularity: Regularly occurring

Currently: Unknown/Undetermined

Confidence: Confident

Flax species do best on well-drained soils. Most ecotypes do well on infertile, disturbed soils. They have excellent cold winter and drought tolerance. They will tolerate weakly saline to weakly acidic sites. Plants are usually found in open areas, but will tolerate semi-shaded conditions. They are fire resistant due to leaves and stems staying green with relatively high moisture content during most of the fire season.

Lewis flax can be found from Alaska to California and east to Minnesota in mixed grass, sagebrush, shadscale, piñon-juniper, mountain brush and aspen communities and in openings in coniferous forests. Blue flax is native to Eurasia and has been planted successfully throughout the United States. For current distribution, consult the Plant Profile page for this species on the PLANTS Web site.

More info for the terms: capsule, caudex, forb

This description provides characteristics that may be relevant to fire ecology of Lewis flax, and is not meant for identification. Keys for identification are available [33,39,40,52,59,68,69,122].

Lewis flax is a native, semievergreen, perennial forb. It has several glabrous, erect stems (8 to 28 inches (20-70 cm) tall) arising from a persistent, branched caudex and taproot [61,63]. The leaves are numerous, alternate, linear to lanceolate, and glabrous. Flowers are borne on a leafy, 1-sided raceme. Flowers open at sunrise and petals fall by noon [4,121]. The capsule is ovoid to globose, splitting from the top downward into ten 1-seeded segments [33,59,68,122].

More info for the terms: scoria, xeric

Lewis flax occurs on valley bottoms, benches, slopes, ridges, and meadows, from prairie to alpine elevations [64,121]. It grows best in full sunlight and has little to no shade tolerance [61,62,121]. Site descriptions by state are provided below.

State, Region, Province	Site Characteristics
Arizona	open mesas, rocky hills and slopes, and coniferous forests; 3,500 to 9,500 feet (1,100-2,900 m) [69,130]
Pima County, Arizona	widely scattered on flats and bajadas; 2,200 to 2,400 feet (670-720 m) [137]
California	dry open ridges and slopes; 1,300 to 11,000 feet (400-3,400 m) [59,91]
Colorado	plains to upper montane [132]
Nevada	washes, cliff basins, mesas to mountain slopes; 4,500 to 9,000 feet (1,400-2,700 m) [16,68]
Utah	xeric to mesophytic, gravelly hillsides and montane forest zones; 4,500 to 9,500 feet (1,400-2,900 m) [3,36]
Wyoming	plains to alpine [40]
Black Hills, South Dakota	plains, hills, and slopes [39]
Pacific Northwest	prairies to alpine ridges, usually on dry, well-drained soil [60]
Baja California	gravelly soil, margins of meadows, and rocky ridges [138]
Neuvo Leon	alpine meadows above 11,000 feet (3,500 m) [15,19]

Climate: Lewis flax is suitable for sites with average annual precipitation that ranges from 10 to 23 inches (250-580 mm). Vigorous growth can be expected on sites averaging greater than 16 inches (410 mm) [61,121]. Lewis flax seedlings are "excellent competitors" in pinyon-juniper types that average <15 inches (380 mm) annual precipitation and are "medium competitors" on sites that average more than 15 inches (380 mm) annual precipitation. Mature plants are "medium competitors" at both of these precipitation levels [118].

Soils: Lewis flax thrives on well-drained porous soils ranging from moderately basic to weakly acidic. It is intolerant of poor drainage, flooding and high water tables [62,121].

Soil characteristics for sites that Lewis flax is known to occur on grassland types in North Dakota are as follows [136]:

The little bluestem-needle-and-thread grass-threadleaf sedge (Schizachyrium scoparium-Hesperostipa comata-Carex filifolia) type has soils that are composed of 70% sand, 18% silt, and 12% clay and pH between 7.3 to 8.6. These soils are relatively shallow with parent materials of sandstone, shale, or siltstone frequently within 10 to 20 inches (41-51 cm) of the surface. The needle-and-thread grass-plains muhly (Muhlenbergia cuspidata)-carex (Carex duriuscula and C. filifolia) type has extremely shallow soils with bedrock, gravel, or scoria close to the surface, pH between 7.2 to 8.9, and percentages for sand, silt, and clay are 46, 19, 35, respectively. The big bluestem-porcupine grass-prairie dropseed (Andropogon gerardii-Stipa spartea-Sporobolus heterolepis) occupies shallow soils with an average pH of 7.3. Soils were 64% sand, 24% silt, 15% clay [136].

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This species is known to occur in association with the following Rangeland Cover Types (as classified by the Society for Range Management, SRM):

More info for the terms: cover, shrub

SRM (RANGELAND) COVER TYPES [110]:

101 Bluebunch wheatgrass

102 Idaho fescue

104 Antelope bitterbrush-bluebunch wheatgrass

105 Antelope bitterbrush-Idaho fescue

107 Western juniper/big sagebrush/bluebunch wheatgrass

108 Alpine Idaho fescue

109 Ponderosa pine shrubland

209 Montane shrubland

210 Bitterbrush

301 Bluebunch wheatgrass-blue grama

302 Bluebunch wheatgrass-Sandberg bluegrass

303 Bluebunch wheatgrass-western wheatgrass

304 Idaho fescue-bluebunch wheatgrass

309 Idaho fescue-western wheatgrass

310 Needle-and-thread-blue grama

314 Big sagebrush-bluebunch wheatgrass

315 Big sagebrush-Idaho fescue

317 Bitterbrush-bluebunch wheatgrass

318 Bitterbrush-Idaho fescue

320 Black sagebrush-bluebunch wheatgrass

321 Black sagebrush-Idaho fescue

401 Basin big sagebrush

402 Mountain big sagebrush

403 Wyoming big sagebrush

405 Black sagebrush

408 Other sagebrush types

411 Aspen woodland

412 Juniper-pinyon woodland

413 Gambel oak

414 Salt desert shrub

415 Curlleaf mountain-mahogany

416 True mountain-mahogany

420 Snowbrush

501 Saltbush-greasewood

502 Grama-galleta

504 Juniper-pinyon pine woodland

601 Bluestem prairie

604 Bluestem-grama prairie

606 Wheatgrass-bluestem-needlegrass

607 Wheatgrass-needlegrass

608 Wheatgrass-grama-needlegrass

609 Wheatgrass-grama

610 Wheatgrass

611 Blue grama-buffalo grass

612 Sagebrush-grass

614 Crested wheatgrass

704 Blue grama-western wheatgrass

705 Blue grama-galleta

706 Blue grama-sideoats grama

708 Bluestem-dropseed

709 Bluestem-grama

710 Bluestem prairie

713 Grama-muhly-threeawn

714 Grama-bluestem

715 Grama-buffalo grass

802 Missouri prairie

803 Missouri glades

ALASKAN RANGELANDS

906 Broadleaf forest

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

More info for the term: cover

SAF COVER TYPES [46]:

16 Aspen

107 White spruce

201 White spruce

202 White spruce-paper birch

203 Balsam poplar

206 Engelmann spruce-subalpine fir

209 Bristlecone pine

210 Interior Douglas-fir

211 White fir

215 Western white pine

217 Aspen

218 Lodgepole pine

219 Limber pine

220 Rocky Mountain juniper

229 Pacific Douglas-fir

237 Interior ponderosa pine

238 Western juniper

239 Pinyon-juniper

244 Pacific ponderosa pine-Douglas-fir

245 Pacific ponderosa pine

247 Jeffrey pine

251 White spruce-aspen

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

More info for the term: shrub

KUCHLER [77] PLANT ASSOCIATIONS:

K005 Mixed conifer forest

K008 Lodgepole pine-subalpine forest

K009 Pine-cypress forest

K010 Ponderosa shrub forest

K011 Western ponderosa forest

K012 Douglas-fir forest

K016 Eastern ponderosa forest

K017 Black Hills pine forest

K018 Pine-Douglas-fir forest

K019 Arizona pine forest

K020 Spruce-fir-Douglas-fir forest

K021 Southwestern spruce-fir forest

K022 Great Basin pine forest

K023 Juniper-pinyon woodland

K024 Juniper steppe woodland

K031 Oak-juniper woodland

K032 Transition between K031 and K037

K034 Montane chaparral

K037 Mountain-mahogany-oak scrub

K038 Great Basin sagebrush

K039 Blackbrush

K040 Saltbush-greasewood

K050 Fescue-wheatgrass

K051 Wheatgrass-bluegrass

K052 Alpine meadows and barren

K053 Grama-galleta steppe

K055 Sagebrush steppe

K056 Wheatgrass-needlegrass shrubsteppe

K063 Foothills prairie

K064 Grama-needlegrass-wheatgrass

K065 Grama-buffalo grass

K066 Wheatgrass-needlegrass

K067 Wheatgrass-bluestem-needlegrass

K068 Wheatgrass-grama-buffalo grass

K069 Bluestem-grama prairie

K074 Bluestem prairie

K075 Nebraska Sandhills prairie

K088 Fayette prairie

K093 Great Lakes spruce-fir forest

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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):

ECOSYSTEMS [49]:

FRES11 Spruce-fir

FRES19 Aspen-birch

FRES20 Douglas-fir

FRES21 Ponderosa pine

FRES22 Western white pine

FRES23 Fir-spruce

FRES26 Lodgepole pine

FRES29 Sagebrush

FRES30 Desert shrub

FRES32 Texas savanna

FRES34 Chaparral-mountain shrub

FRES35 Pinyon-juniper

FRES36 Mountain grasslands

FRES37 Mountain meadows

FRES38 Plains grasslands

FRES39 Prairie

FRES44 Alpine

Lewis flax is a dominant species in the Colville's phlox (Phlox covillei)/Lewis
flax alpine community of the White Mountains in California [81].

Planting: Flax should be seeded with a drill or broadcast at a depth of 1/4 inch or less into a firm seedbed. The ideal seeding depth is 1/8 inch. Flax is not recommended for single species seedings. The full seeding rate (not recommended) for these forbs is 4 pounds Pure Live Seed (PLS) per acre or 24 PLS per square foot. When used as a component of a mix, adjust to percent of mix desired. For mined lands and other harsh critical areas, doubling the seeding rate component of flax is not required.

The best seeding results are obtained from seeding in late fall to very early spring (because of grass component of mix) on heavy to medium textured soils and in late fall on medium to light textured soils. Late summer (August - mid September) seeding is not recommended. Dormant fall seedings (preferred seeding period for flax) will pre-chill seed and reduce seed dormancy which may be present. Mulching, irrigation, and weed control all benefit stand establishment. Seedling vigor is good, but not as good as most grasses. Germination normally occurs the first growing season, but may not occur until the second growing season. Full flowering should not be expected until at least the second growing season.

Stands may require weed control measures during establishment. Because flax is a broadleaf plant, use of 2,4-D is not recommended. Mow weeds at or prior to their bloom stage. Grasshoppers and other insects may also damage new stands and pesticides may be needed.

More info for the terms: cover, fuel

Lewis flax maintains its green basal foliage year round and "does not readily burn". These traits may make it useful in vegetative fuel breaks to reduce the spread of fire [57,117]. It is frequently used in greenstripping projects throughout the Intermountain west because of its large ecological amplitude, ability to compete with annual weeds, ease of establishment, low flammability, and resilience and regrowth capabilities [85,95,96].

Postfire seeding with Lewis flax may be a viable postfire management option. Lewis flax appears to establish more readily on burned than unburned microsites following postfire broadcast seeding in meadows dominated by basin big sagebrush. A study done in the Toiyabe Mountains of Nevada measured the response of certain species while managing and restoring basin big sagebrush. The study sites were representative of dry meadow vegetation, and depth to water table was described as wet, intermediate, or dry. Treatment sites were burned and then seeded. Seedling establishment was recorded for each site from the 1st through the 3rd growing season. Lewis flax occurred on the wet and dry sites, but was not recorded on the control or intermediate sites [140,141].

Postfire establishment of Lewis flax seeded onto burned slash pile microsites under ponderosa pine in Arizona appears successful. Piles of slash were burned in February 2000 and subsequently underwent 1 of 5 site amelioration treatments. These treatments were: 1) no treatment; 2) living soil amendment (containing micro-organisms, arbuscular mycorrhizae, and plant propagules); 3) sterilized soil amendment (no propagules); 4) native seed amendment; and 5) seed/soil amendment. Establishment of Lewis flax was significantly higher (P ≤ 0.05) when seeded in conjunction with soil amendment. The average cover of Lewis flax for the native seed and seed/soil amendment plots is detailed below [75].

	Treatment 4	Treatment 5
2000	0.01 ± 0.01	0.11 ± 0.04
2001	0 ± 0	0.13 ± 0.07

More info for the terms: cover, prescribed fire

The impacts of fire and herbivory were the focus of a study done in Jasper National Park in Alberta, Canada,
where Lewis flax cover increased 2 years after fire in closed-canopy plots accessible to elk, but was not
significantly different on open-canopy plots or those where elk were excluded. Lewis flax cover in all
treatements averaged less than 1%. Plots were subjected to a low-intensity prescribed fire in May 1999,
with a rate of spread of 2 to 5 m/min and flame lengths of 10 to 20 cm with occasional "candling".
Percent ground cover of Lewis flax is detailed in the table below [2].

	Closed canopy		Open canopy
	Preburn 1998	Postburn 2001	Preburn 1998	Postburn 2001
No exclosure	0.02*	0.28	0.1	0.0
Exclosure	0.03	0.10	0.2	0.13

*bold indicates a significant difference between years at P = 0.05

More info for the term: caudex

Lewis flax is likely to survive and sprout from the caudex after fire, although no direct observations of this are reported in the literature.

Anecdotal information provided by Wasser [131] indicates that Lewis flax may establish from seed after fire. Lewis flax was present on burned sites and not on unburned sites in blackbrush communities in southern Nevada [24], suggesting that it recovers from an off-site seed source or from soil stored seed. Lewis flax seeds are capable of surviving in the soil for "multiple" years [73], so it is possible that Lewis flax may recover from the seed bank after fire. However, further research is needed on how Lewis flax seeds respond to fire.

More info for the term: severity

Lewis flax is likely top-killed in the event of high severity fire. Lewis flax maintains some green basal foliage year-round and, according to anecdotal information provided by Stevens and Monsen [117], "does not readily burn".

More info for the terms: ground residual colonizer, secondary colonizer

POSTFIRE REGENERATION STRATEGY [119]:
Ground residual colonizer (on-site, initial community)
Secondary colonizer (on-site or off-site seed sources)

More info for the term: stand-replacement fire

Fire adaptations: Lewis flax maintains some green basal foliage year round and, according to anecdotal information provided by Stevens and Monsen [117], "does not readily burn". Information provided by Wasser [131] indicates that Lewis flax may be killed by fire and that it may establish from seed after fire.

FIRE REGIMES: Lewis flax most commonly occurs in communities that are characterized by short fire-return intervals and mixed-severity or stand-replacement fire types.

The following table provides fire return intervals for plant communities and ecosystems where Lewis flax is important. For further information, see the FEIS review of the dominant species listed below.

Community or Ecosystem	Dominant Species	Fire Return Interval Range (years)
bluestem prairie	Andropogon gerardii var. gerardii-Schizachyrium scoparium	76,94]
Nebraska sandhills prairie	A. gerardii var. paucipilus-Schizachyrium scoparium	94]
silver sagebrush steppe	Artemisia cana	5-45 [58,101,139]
sagebrush steppe	A. tridentata/Pseudoroegneria spicata	20-70 [94]
basin big sagebrush	A. tridentata var. tridentata	12-43 [105]
mountain big sagebrush	A. tridentata var. vaseyana	15-40 [7,27,84]
Wyoming big sagebrush	A. tridentata var. wyomingensis	10-70 (x=40) [127,142]
saltbush-greasewood	Atriplex confertifolia-Sarcobatus vermiculatus	94]
plains grasslands	Bouteloua spp.	94,139]
blue grama-needle-and-thread grass-western wheatgrass	B. gracilis-Hesperostipa comata-Pascopyrum smithii	94,104,139]
blue grama-buffalo grass	B. gracilis-Buchloe dactyloides	94,139]
grama-galleta steppe	B. gracilis-Pleuraphis jamesii	94]
cheatgrass	Bromus tectorum	99,135]
California montane chaparral	Ceanothus and/or Arctostaphylos spp.	50-100 [94]
curlleaf mountain-mahogany*	Cercocarpus ledifolius	13-1,000 [9,107]
mountain-mahogany-Gambel oak scrub	C. ledifolius-Quercus gambelii	<35 to <100
blackbrush	Coleogyne ramosissima	<35 to <100
western juniper	Juniperus occidentalis	20-70
Rocky Mountain juniper	J. scopulorum	<35 [94]
wheatgrass plains grasslands	Pascopyrum smithii	<5-47+ [94,101,139]
Engelmann spruce-subalpine fir	Picea engelmannii-Abies lasiocarpa	35 to >200 [6]
pinyon-juniper	Pinus-Juniperus spp.	<35 [94]
Rocky Mountain bristlecone pine	P. aristata	9-55 [37,38]
Rocky Mountain lodgepole pine*	P. contorta var. latifolia	25-340 [12,13,124]
Sierra lodgepole pine*	P. contorta var. murrayana	35-200 [6]
Colorado pinyon	P. edulis	10-400+ [48,51,72,94]
Jeffrey pine	P. jeffreyi	5-30
western white pine*	P. monticola	50-200
Pacific ponderosa pine*	P. ponderosa var. ponderosa	1-47 [6]
interior ponderosa pine*	P. ponderosa var. scopulorum	2-30 [6,11,80]
Arizona pine	P. ponderosa var. arizonica	2-15 [11,31,109]
aspen-birch	Populus tremuloides-Betula papyrifera	35-200 [41,128]
quaking aspen (west of the Great Plains)	P. tremuloides	7-120 [6,53,83]
mountain grasslands	Pseudoroegneria spicata	3-40 (x=10) [5,6]
Rocky Mountain Douglas-fir*	Pseudotsuga menziesii var. glauca	25-100 [6,7,8]
coastal Douglas-fir*	P. menziesii var. menziesii	40-240 [6,88,103]
oak-juniper woodland (Southwest)	Quercus-Juniperus spp.	<35 to <200 [94]
Fayette prairie	Schizachyrium scoparium-Buchloe dactyloides	<10 [128]
little bluestem-grama prairie	S. scoparium-Bouteloua spp.	<35 [94]

*fire return interval varies widely; trends in variation are noted in the species review

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More info for the terms: forbs, frequency

Lewis flax is a pioneer, early-, and late-seral species in mountain brush, pinyon-juniper, and ponderosa pine (Pinus ponderosa) communities of the Intermountain West [118,129]

Lewis flax is 1 of the forbs with highest frequency on a 40- to 50-year-old burn in west-central Montana. Douglas-fir, lodgepole pine, and quaking aspen were representative small trees regenerating on this site [106].

More info for the terms: caudex, fitness, hypocotyl, litter

Lewis flax regenerates from seed and by sprouting from the caudex [85,117].

Pollination: Lewis flax is pollinated by flies, bees, and other insects in Colorado [1,70,71]. In western North Dakota populations, bees and flies were the most common visitors [79]. It is also probable that Lewis flax is wind pollinated [92].

In montane habitats above 9,100 feet (2,800 m) at the Rocky Mountain Biological Laboratory in Colorado, flies were more common than bees as pollinators of Lewis flax. Bees are more effective than flies at depositing pollen, but mean bee visitation of Lewis flax was lowest at the high-elevation site in all years. The lower number of bee visits at higher elevation sites could be because the dilute nectar available from Lewis flax flowers is less attractive than the nectar-rich flowers of other species that occur in alpine areas, or because there is  a decrease in the number of solitary bees at high elevations [70,71].

Pollen-eating muscoid flies are common pollinators of Lewis flax in Colorado. One Lewis flax flower produces fewer than 3,500 grains of pollen during the 1-day flowering period. These flies are known to eat more than 1,000 grains in a day and could have a negative impact on plant paternal fitness [71].

Breeding system: Lewis flax is a self-fertile homostylous species. Most species in this group are obligate outcrossing perennials [70,71].

Seed production: The spherical capsules of Lewis flax produce up to 10 seeds each. Many seeds are immature upon dispersal and must undergo an afterripening period before germinating [111,117].

Although Lewis flax is self-compatible, pollination by insects is needed for seed production [70,71]. In her study on the role of fly pollination in montane habitats, Kearns [71] grew 5 Lewis flax plants under laboratory conditions. The plants received no pollination treatments or insect visits. The 5 plants produced 438 flowers, none of which produced fruits with seeds [71].

Lewis flax seed set differed significantly (p = 0.0001) among low-, mid-, and high-elevation sites and among years (P = 0.03). Seed set decreased with increasing elevation. The lower seed set at higher elevations could be due to pollen limitation (see Pollination) or could be due to the shorter growing season and extreme weather conditions in alpine areas [71].

A study of Lewis flax plants transplanted from steppe and forest communities above the Yukon River at Eagle, Alaska indicates that light and water availability affect Lewis flax seed production. Reproducing individuals grown in the shade had an 87% reduction in total seed biomass. An increase in light significantly (P ≤ 0.05) affected seed production. Total seed biomass increased nearly fivefold with added moisture and was significant at the P ≤ 0.01 level [134].

Seed dispersal: No information is available on this topic.

Seed banking: Seed banking and longevity under field conditions have not been well studied for this species, although Kitchen [73] suggests that seeds survive for "multiple" years. Evidence of an afterrippening period for Lewis flax seeds (see Germination) suggests that they may remain viable in the soil for extended periods; however, further research is needed on the seed banking capabilities of Lewis flax.

Germination: Many Lewis flax seeds germinate in 10 to 15 days indoors at 60 to 70 °F (16-21 °C), and in 15 to 30 days in the field, under variable moisture and temperature conditions [131]. Lewis flax seeds taken from a high mountain grassland study site in western Colorado were germinated in a greenhouse setting. The optimum temperature regime for seed germination was 59 °F (15 °C). The cumulative percentages for Lewis flax seeds that germinated are presented below [93].

Observation days	7	14	21	28	35
Cumulative percent germination	16	80	86	86	86

Duration and climatic conditions of storage affect germination rates of Lewis flax [21,66,74] and suggests that Lewis flax is able to germinate under variable conditions. Jorgensen and Wilson [66] revealed that Lewis flax seeds germinated in the dark at 34 to 38 °F (1.1- 3.3 °C), and had a mean germination rate of 55% at ~35 days and 75% at ~55 days. A germination study using Lewis flax seeds from 21 Utah, Idaho, Nevada, and Washington populations found that percent germination for seeds recently harvested was 17% to 100% with no prechill period (control), 28% to 100% for seeds that underwent a 28-day prechill period, and 32% to 100% for those with a 168-day prechill period [74]. These results suggest that average germination of Lewis flax seeds increases the longer they are prechilled. Conversely, greenhouse germination trials revealed that the greatest percent germination of Lewis flax seeds occurred after being stored dry, at room temperature. There was a decrease in percent germination for seeds stored in dry, cold storage and wet, cold storage. The seeds used in the trials were collected during the summer on western North Dakota native ranges. The storage period for all treatments began December 1, and germination tests began on the 10th of each month and were observed for 60 days. The percent germination of Lewis flax seeds is presented below [21].

Month	January	February	March	April	May
Dry-room temperature storage	16	23	36	33	79
Dry-cold storage	4	25	16	13	43
Wet-cold storage	14	25	1	41	20

Lewis flax seeds may have an afterripening period, in that they initially exhibit low germination rates that increase after a period of storage [21,66,74]. Lewis flax germination was recorded, over a 25 year period, for seeds stored in an open, unheated, and uncooled warehouse. Greatest germination occurred after 5 years of storage. Percent germination of Lewis flax seeds after 2 to 25 years of storage in an open warehouse are presented below [115].

Years of Storage	2	3	4	5	7	10	15	20	25
Percent germination	66	72	85	93	83	70	25	8	0

Seedling establishment/growth: The seed coat of Lewis flax seed is mucilaginous (secretes a gelatinous or gummy substance). The mucilage adheres to the soil when hydrated, resulting in seed retention on site [30] and allowing for establishment on bare soil. Lewis flax seedlings have a thin, vigorous root, 1/3 to 1/2 the length of the hypocotyl [17]. Seedlings are vigorous, and have a rapid growth rate [87].

Leachates from singleleaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma) litter may inhibit Lewis flax seedling establishment. In a greenhouse study, buried seeds emerged more frequently from mineral soil than from pots with singleleaf pinyon and Utah juniper litter. When Lewis flax seeds were broadcast seeded, emergence was greater on singleleaf pinyon litter than on either Utah juniper litter or mineral soil [44]. Everett [44] speculates that allelopathic effects of pinyon litter on broadcast seeds are offset by improved surface microenvironment and reduced seed desiccation.

A seedling establishment study done in southwestern Colorado's San Juan Basin Research Center reports that Lewis flax seedlings have a better chance of establishing if seeds are planted in fall rather than spring. Three separate plantings were done in April, May, and October of the 1st year, and in May, June, and October of the 2nd year. Establishment ratings were assigned to the stands based on visual observations made in May of the following year. Lewis flax seedling establishment was higher for October plantings than spring plantings in both years. Establishment ratings are summarized below [47].

Date of planting	Establishment rating*
1982
April 16	1.13
May 17	1.83
October 21	3.75
1983
April 20	1.00
June 9	1.63
October 17	3.60

* 1=1% to 25%, 2=25% to 50%, 3=50% to 75%,
4=75% to 100% of complete stand (12 plants/m of row)

Asexual regeneration: Lewis flax sprouts from the caudex [85].

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More info for the term: hemicryptophyte

RAUNKIAER [102] LIFE FORM:
Hemicryptophyte

More info for the terms: forb, shrub

Forb-shrub

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Lewis flax normally requires 2 to 3 years to establish, mature, and flower [114]. Wasser [131] states that it might begin to flower by the 3rd year or, under more favorable conditions, by the end of the 2nd. Lewis flax maintains some green basal foliage year-round [117].

Lewis flax flowering periods were studied for 8 years in Saskatchewan. The mean first-flower date was June 5. The earliest flower date was May 19 and the latest was June 19. The latest date a plant was in flower was recorded as July 27. The mean flowering period was 33 days [26]. The following table provides flowering dates for Lewis flax.

State, Region, Province	Anthesis Period
Arizona	March to September [69]
California	May to September [91]
Nevada	April to August [16,68]
West Virginia	June and July [122]
Baja California	March to September [138]
Pacific Northwest	May to July [60]
Canada	late May [32]

Lewis flax seeds mature in late July and August [117].

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 3
Specimens with Barcodes: 8
Species With Barcodes: 1

Information on state-level protected status of plants in the United States is available at Plants Database.

Canada

Rounded National Status Rank: N5 - Secure

United States

Rounded National Status Rank: NNR - Unranked

Rounded Global Status Rank: G5 - Secure

Consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status and wetland indicator values.

More info for the terms: cover, forbs, presence, shrubs

An important aspect in management considerations for Lewis flax is its tolerance
of disturbance from grazing and herbicide applications.

Grazing: Lewis flax can survive heavy grazing
after it is established [61] and in most cases is an increaser [78]. Two pastures on mixed prairie grassland
near Fort Collins, Colorado were studied to find effects of 2 different management systems: deferred rotation
grazing and continuous grazing. The findings are summarized below [56].

	Number of quadrats in which Lewis flax occurred	Total number of Lewis flax individuals
Deferred Rotation Pasture	2	2
Continuously Grazed Pasture	6	22

A floristic inventory was conducted on 4 heavily used black-tailed prairie dog towns in Billings County,
North Dakota. Horses, cattle, and native ungulates contributed to the high level of disturbance in these
areas. The presence of Lewis flax was recorded on 1 of 4 prairie dog towns, confirming its ability to
survive in highly disturbed areas [120].
Research on an Idaho fescue-bluebunch wheatgrass grassland in southwestern Montana suggests that Lewis
flax survives under a variety of grazing regimes. Lewis flax cover in ungrazed, lightly grazed, and heavily
grazed sites ranged from 0 to 2.1 cm²/0.1m². No statistically significant differences were reported [43].
Lewis flax was listed as an indicator for range readiness in the Swift Current district, Saskatchewan:
"range will  be ready to graze when the plants commence blooming" [26].
Herbicide: In a study done on the effects of 2, 4-D on forbs
and shrubs associated with big sagebrush in Idaho, Lewis flax was unharmed by applications of 2, 4-D [22].

Foundation and registered seed is available for each variety through the appropriate state Crop Improvement Association or commercial sources to grow certified seed.

'Appar' blue flax (Linum perenne) is a selected release from seed originally collected in the Black Hills of South Dakota. 'Appar' was selected by the Forest Service Forest and Range Experiment Station and Aberdeen Plant Materials Center for outstanding vigor, beauty, and competitiveness with grasses prevalent on sites where it was collected. The Natural Resources Conservation Service, University of Idaho Agricultural Experiment Station, Utah Division of Wildlife Resources, and the Forest Service Forest and Range Experiment Station released 'Appar' in 1980. 'Appar' was released as native flax (Linum lewisii), but was later determined to be a naturalized introduced species from European origins. 'Appar' was named in honor of A. Perry Plumber, Forest Service (retired) who collected the original material. 'Appar' is a hardy, relatively short-lived, introduced perennial forb, 12 to 36 inches tall, with deep blue flowers that bloom profusely for about six weeks beginning in mid May. It is well adapted to sunny open slopes, well-drained soils from moderately basic to weakly acidic, 10 to 18 inch rainfall areas, at 1,000 to 6,000 feet elevation. It has some shade tolerance, but is not tolerant of poor drainage, flooding, or high water tables. It does well seeded in mixtures with other species. Its intended uses are erosion control, reclamation, highway right-of-ways, homes, gardens, parks, diversity, and beautification. Certified seed is readily available through commercial sources and breeder seed is maintained by Aberdeen Plant Materials Center.

Maple Grove Germplasm Lewis flax (Linum lewisii) is a recent (2003) Selected class Germplasm release of a native collection from the Maple Grove, Utah area. Maple Grove was selected by the Forest Service Forest and Range Experiment Station and Aberdeen Plant Materials Center for outstanding vigor, beauty, and competitiveness with grasses prevalent on sites where it was collected. The Natural Resources Conservation Service, University of Idaho Agricultural Experiment Station, Utah Division of Wildlife Resources, and the Forest Service Forest and Range Experiment Station released Maple Grove in 2003. Maple Grove is a hardy, relatively short-lived, native perennial forb, 12 to 36 inches tall, with light blue flowers that bloom profusely for about six weeks beginning in mid May. It is well adapted to sunny open slopes, well-drained soils from moderately basic to weakly acidic, 10 to 18 inch rainfall areas, at 1,000 to 6,000 feet elevation. It has some shade tolerance, but is not tolerant of poor drainage, flooding, or high water tables. It does well seeded in mixtures with other species. Its intended uses are erosion control, reclamation, highway right-of-ways, homes, gardens, parks, diversity, and beautification. Certified seed is available through the University of Idaho Foundation Seed Program and Utah Crop Improvement Associations and Soil Conservation Districts in Idaho, Utah and Nevada. Certification of seed shall be limited to not more than two generations from the G3 seed.

There are numerous flax species native to the U.S. that may be available through native plant nurseries and seed companies. These include the following: Linum alatum (TX & LA), Linum arenicola (FL), Linum aristatum (UT & AZ to TX), Linum berlandieri (CO to LA), Linum catharticum (northeast US), Linum compactum (MT & ND to NM & TX), Linum intercursum (Atlantic states), Linum lewisii (central & west US), Linum medium (east & central US), and Linum virginianum (east & midwest US). Please check the PLANTS database for other native flax species.

Contact your local Natural Resources Conservation Service (formerly Soil Conservation Service) office for more information. Look in the phone book under ”United States Government”. The Natural Resources Conservation Service will be listed under the subheading “Department of Agriculture.”

Flax should be seeded in 24 inch rows at the rate of 2.5 pounds PLS per acre or 36 inch rows at the rate of 1.5 pounds PLS per acre (25 to 30 seeds per linear foot of row) to allow mechanical weed control. It should be seeded in early spring (April - May).

Hand rouging within row and cultivation between rows may be required. Split applications of nitrogen in spring and fall and application of phosphorus in fall will enhance production. For optimum production, do not stress plants for moisture during late bud stage, pollination and re-growth.

Seed is generally harvested in late July to mid-August by wind-rowing before seed shatter and combining with pickup attachment once green stems have dried. Seed is mature when capsules are dry and seed is hard and dark in color. Flowering is indeterminate with mature capsules and the possibility of some flowers present at harvest period. Some seed will shatter once capsules open. Seed should be allowed to dry to 12 (bins) to 15 (sacks) percent moisture and then stored in a cool dry area. Seed retains viability for several years under these conditions.

Seed yields of 600 to 700 pounds per acre of blue flax can be expected under irrigated conditions and 200 to 300 pounds per acre under dryland conditions.

Seed yields of Lewis flax from irrigated fields average 300 to 350 pounds per acre. Seed production of Lewis flax under dryland conditions is not recommended below 16 inches of average annual rainfall.

Growth of flax begins in early spring and flowers appear in mid May through early July depending on species. Weed control and removal of very competitive species may improve chance of establishment. Damage from wildlife and rodents may occur and they may need to be controlled. Disease problems are minimal with flax; however fungus problems have been noted for some native species.

Environmental Concerns: Flax species establish relatively quickly and easily via seed under favorable climatic conditions. They are not rhizomatous or considered "weedy" or invasive species, but could spread into adjoining vegetative communities under ideal climatic and environmental conditions. They coexist with other species and add biodiversity to those plant communities. ‘Appar’ blue flax seed normally germinates the first growing season following planting under favorable temperatures if moisture is available and it generally does not maintain a viable seed-bank. Native flax accessions tested maintain a portion of seed, which does not germinate the first growing season, as a viable seed-bank.

More info for the term: fresh

Lewis flax was an important plant used by Native Americans. The strong fibers from the stem were made into cords and strings and used in baskets, mats, meshes of snowshoes, and in the weaving of fishing nets. Lewis flax seeds were used in cooking, as they have a pleasant taste and are highly nutritious. Stems were steeped for stomach disorders and roots steeped for eye medicine. The whole plant was also used to make an eye medicine by mashing and soaking it in cold water. Poultices of the crushed fresh leaves were used to reduce swellings, especially for goiter and for gall trouble. Early settlers made a poultice of the powdered seed, corn meal, and boiling water, mixing this into a paste for infected wounds and mumps [123,125].

More info for the terms: cover, reclamation

Lewis flax is commercially grown and planted throughout the Intermountain West [117]. It is used in the reclamation of mining sites and spoils, roadsides, and construction sites [23,25,34,61,62,108]. Germination of Lewis flax seeds directly seeded into coal mine spoils at Dickenson, North Dakota was successful, and resulted in 43 seedlings/m² after 120 days. This is a low number, however, compared to other species that had over 300 seedlings/m² [21]. Another reclamation study on coal mine spoils in North Dakota groups Lewis flax with plants described as "showing excellent establishment characteristics, even though they did not make outstanding height growth or provide exceptionally good cover." It was also noted that Lewis flax "appeared to show little promise because of low germination and/or survival for use in revegetation trials on spoil bank material" [20].

Lewis flax is a desirable species to seed for rehabilitation of rangelands and shrublands [85,129]. Transplanting Lewis flax is usually very successful and establishment can be expected when proper transplanting techniques are used [112]. In arid climate landscapes, the heat/drought-tolerant Lewis flax can be a substitute for plants that require more water [54]. Its ease of establishment is noted as "excellent" [85]. However, because Lewis flax seeds are eaten by deer mice in some vegetation types, they may not be appropriate to use in seed mixes. Everett, Meeuwig, and Stevens [45] suggest not using highly preferred seeds in some seed mixes, planting desirable species whose seeds are not preferred by deer mice, or treating desirable seeds with a repellent.

Lewis flax shows low potential for use in revegetation of subalpine sites or wildlife habitat improvement in Colorado [121,131].

Nonnative Species: Lewis flax is a strong competitor against spotted knapweed (Centaurea maculosa). A common garden experiment at The University of Montana Diettert Experimental Gardens in Missoula, Montana, revealed that aboveground biomass of spotted knapweed was lower (~1 g) when planted with Lewis flax versus spotted knapweed grown alone (~4.5 g). Fungicide added to the soil did not affect Lewis flax growth or how Lewis flax interacted with spotted knapweed [28].

When seeded in mixtures into cheatgrass (Bromus tectorum)-dominated communities, Lewis flax establishes and spreads quickly, occupying both open areas and those dominated by annual weeds [117].

More info for the term: cover

Livestock: The early green foliage of Lewis flax is sought out by livestock [61,62]. However, domestic sheep are reported to have been poisoned by grazing on Lewis flax, which has been shown to contain a cyanogenetic substance (capable of making cyanide) [1,42]. Dittberner and Olson [35] also list Lewis flax as a plant suspected to be poisonous to livestock.

Big game: The early green foliage of Lewis flax is readily eaten by elk, mule deer, white-tailed deer, and pronghorn [10,55,61,62,82,89,100].

A study done at the Desert Experimental Range of the Intermountain Forest and Range Experiment Station, Utah revealed that Lewis flax has a high preference rating as antelope forage and is generally used during the summer and fall. The preference rating was higher during wet years versus dry years because in wet years there is a greater abundance of Lewis flax available [14].

Birds: The seeds of Lewis flax are sought out by birds during the fall and winter months [61,100,121]. It is desirable for sage-grouse and Columbian sharp-tail grouse habitat [113].

Other small mammals: Lewis flax is "never edible" to golden-mantled ground squirrel, and "seldom edible" to the least chipmunk in trapped and caged populations taken from a rocky, meadow habitat in the mountains of west-central Colorado [29].

Feeding trials with trapped deer mouse populations revealed that Lewis flax seeds were preferred, and comprised of 16.3% of their diet. The deer mice were trapped in big sagebrush-antelope bitterbrush (Artemisia tridentata-Purshia tridentata), singleleaf pinyon-Utah juniper, and Jeffrey pine-snowbrush ceanothus (Ceanothus velutinus) vegetation types in western Nevada. Preference rating (scale of 1 to 18) for Lewis flax seeds for each vegetation type were 6, 7, and 8, respectively [45].

Conversely, Addicott [1] states that the fruit of Lewis flax seems to be avoided by birds, small mammals, and insects.

Palatability/nutritional value: Lewis flax generally has fair palatability to livestock and big game [121]. Palatability of Lewis flax for several western states has been rated as follows [35]:

	Colorado	Montana	North Dakota	Utah	Wyoming
Cattle	fair	fair	fair	poor	fair
Domestic sheep	fair	fair	fair	fair	fair
Horses	fair	fair	fair	poor	fair
Elk	----	poor	----	fair	poor
Mule deer	----	poor	fair	fair	poor
Pronghorn	----	----	good	fair	fair
White-tailed deer	----	----	poor	----	poor
Small mammals	----	poor	----	fair	fair
Small nongame birds	----	poor	----	fair	good
Upland game birds	----	poor	----	fair	poor
Waterfowl	----	----	----	poor	poor

Cover value: Wildlife cover values of Lewis flax for some western states are presented below [35].

	Colorado	North Dakota	Utah	Wyoming
Elk	----	----	poor	poor
Mule deer	----	poor	poor	poor
Pronghorn	----	poor	poor	poor
White-tailed deer	----	poor	----	poor
Small mammals	----	----	fair	poor
Small nongame birds	fair	----	fair	poor
Upland game birds	----	----	fair	poor
Waterfowl	----	----	poor	poor

Ethnobotanic: Cultivated flax (Linum usitatissimum) is grown both for fiber (flax) and seed oil (linseed). Linseed oil may cause skin irritation upon contact.

Ingestion causes difficulty of breathing, paralysis, and convulsions (Russell et al. 1997).

Grazing/rangeland: Blue and Lewis flax are noted to have fair forage value for livestock and wildlife during spring and winter. Plants stay green throughout the growing season providing some forage value. Birds use the seed and capsules in fall and winter. All species provide diversity to the seeded plant community.

Erosion control/reclamation/greenstripping: All flax species are noted for their value in mixes for erosion control and beautification values. The six week flowering period and showy blue flowers make seedings more aesthetically pleasing and increase plant biodiversity. Due to the semi-evergreen nature of the species, flax can also be used as a fire suppressant species in greenstrip plantings.

Wildlife: Flax is considered desirable forage for deer, antelope, and birds, either as herbage or seed. They may also provide some cover for selected small bird species.

Comments: In Kartesz 1999's treatment of Linum, he elevates 'var. lewisii', which many place in L. perenne, to its own species.