BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Krascheninnikovia lanata | Winterfat 



GENERAL BOTANICAL CHARACTERISTICS : 
Winterfat is a native, low-growing, long-lived subshrub with a woody
base and numerous annual branchlets growing 1 to 2 feet (0.3-0.6 m)
tall.  Herbage is hairy giving the plant a silvery white appearance
[62].  The narrow leaves remain on the plant during winter and are shed
when new leaves grow in the spring or when the plant is water stressed
[99].  The flowers are inconspicuous with no petals [62].  The fruit,
0.2-inch (0.5-cm) long, is a utricle enclosed in two bracts covered with
fine, silky, pilose hairs [13].  The oldest winterfat plant in a
community in southwestern Idaho was 136 years old [106].

Winterfat is polymorphic with short and tall ecotypes. The typical
variety is low growing.  Krascheninnikovia lanata var. subspinosa has
taller, woodier stems at the base than the typical variety, and K. l.
var. ruinina is woody for 2.6 feet (0.8 m) from the base, with annual
growth sometimes exceeding 3.9 feet (1.2 m) in height [97].

The root system consists of a deep taproot with numerous branched
lateral roots.  Fibrous roots are contained within the upper meter of
soil but may extend as deep as 57 inches (145 cm).  The taproot may grow
as deep as 25 feet (7.6 m) [85].  In Saskatchewan, a winterfat taproot
penetrated 6 feet (1.8 m) [21], and in western Colorado, winterfat root
depth was 3.1 feet (0.95 m) [14].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Winterfat reproduces by seed and sprouts from buds near the plant's base
when browsed or damaged [111].  Under favorable conditions, winterfat
may produce seed in its first growing season, but it may require up to 5
years to produce seed in areas of low rainfall [85].  Seed production,
especially in desert regions, is dependent on precipitation [101].  Good
seed years occur when there is appreciable summer precipitation and
little browsing [85].  Winterfat produced approximately 350 seeds per
plant on a site in western North Dakota during a slightly drier than
normal year [44].

Seeds are dispersed a short distance by wind.  In a study of seed
dispersal, 67 percent of seed was found within 12 inches (30 cm) of
the parent plant, and no seeds were farther than 35 inches (90 cm) away
[44].  All seedlings observed on southwestern Idaho sites were within 3
feet (1 m) of a mature plant [60].

The hairy bracts help anchor seed to soil which in turn helps the
radicle penetrate and begin growth.  Entire fruits have better seedling
establishment and seedling vigor than threshed seed, which may be
damaged [13].

An undetermined percent of winterfat seeds are dormant when fresh.  A
10-week afterripening period generally breaks dormancy [82].  In the
laboratory, a 14-day prechill period at 41 degrees Fahrenheit (5 deg C)
effectively breaks dormancy of fresh seed [3].

Germination generally occurs during warm, wet weather [1].  Germination
occurs near the soil surface [104].  Seedlings emerged substantially
better from a 0.06-inch (0.02-cm) depth than than from greater depths
[81].  Germination is reduced as moisture stress increases, regardless
of temperature [80].  However, seeds are sensitive to deficient aeration
and have poor germination rates when soils approach saturation.
Germination was best at field capacity soil moisture [81].

Germination of viable seeds generally exceeds 90 percent within a
constant temperature range of 50 to 80 degrees Fahrenheit (10-27 deg C).
Optimum temperatures for germination depend on seed source [105].
Germination is generally complete within 5 days at 59 degrees Fahrenheit
(15 deg C) or higher [83].  Dettori and others [23] achieved greater
than 95 percent germination when they used an alternating temperature
regime with a 32, 36, or 41 degree Fahrenheit (0, 2, or 5 deg C) cold
period and a 59 or 68 degree Fahrenheit (15 or 20 deg C) warm period.
For laboratory germination, a 59 degrees Fahrenheit (15 deg C) constant
temperature for 14 days without light is recommended [3].  Booth [11,12]
reports that post germination growth is affected by mother-plant
transpiration, imbibition temperature, windstress, and nutrition.

As the level of soil salinity increases, germination decreases [17,105].
Choride salts reduce germination more than sulfide salts.  Germination
was severely restricted by soil sodium chloride levels of 2 percent [17]
and 3 percent [105].

Winterfat seeds stored in an open (temperature unregulated) warehouse in
Utah maintained high germination rates (greater than 74%) for 4 years,
but germination after 5 years was only 18 percent, and germination was 0
percent after 10 years of storage [86].  After 8 years of refrigerated
storage at 34 to 42 degrees Fahrenheit (1-6 deg C), viability ranged
from 51 to 80 percent [84].

Natural reproduction in central New Mexico had greatest survival on
disturbed soils with low-growing vegetation that afforded some shelter
but little shade.  By July, when summer rains began, the only seedlings
surviving were either close to mature winterfat, in grass clumps, or in
litter.  The seedling roots penetrated beneath those of the grasses.
Seedlings were successful on land protected from grazing or lightly
grazed range dominated by grasses, but did not survive heavy grazing
[104].  Seedling survival was poor in the Mojave Desert.  Of the 44
seedlings that established on plots during a 5-year period, none lived
to a second growing season [1].




SITE CHARACTERISTICS : 
Winterfat occurs in dry valley bottoms, on flat mesas, and on hillsides.
It occurs on well-drained, calcareous soils with low to moderate salt
concentrations [19,88].  It is a halophytic species which excludes
salt at the roots [19,100].  It often occurs over compact and indurated
calcic horizons [9].  Soil texture apparently does not influence the
distribution of winterfat [95].

Winterfat occurs in arid to semiarid climates with mean annual
precipitation ranging from 5 to 20 inches (130-510 mm) [95].
Elevational ranges for some states are as follows:

Arizona    2,000-7,000 feet 	  (600-2,100 m) [47]
California   300-8,900 feet 	  (100-2,700 m) [42]
Colorado   3,800-9,500 feet     (1,160-2,900 m) [25]
Montana    3,800-5,000 feet     (1,160-1,520 m) [25]
Wyoming    4,000-7,300 feet     (1,200-2,200 m) [25]
Utah       2,400-9,300 feet 	  (730-2,840 m) [97]

In northern climates, winterfat is often found on south- or west-facing
slopes.  It occurs on ridgetops and south- and west-facing slopes in the
Gros Ventre River drainage in northwestern Wyoming [39], and on southern
aspects in coulees in Alberta [52].  In the Kluane Range in Yukon
Territory, winterfat occurs on open, xeric gravelly hillsides [64].
Winterfat is tolerant of cold temperatures.  Lethal temperatures for
winterfat shoots (measured in laboratory tests) were -112 degrees
Fahrenheit (-80 deg C) in winter and -31 degrees Fahrenheit (-35 deg C)
in April [94].  However, newly germinated seedlings are susceptible to
freezing temperatures [85].


SUCCESSIONAL STATUS : 
Winterfat is a component of stable arid shrub communities.  Winterfat
communities have very little change in population over time [16].
Winterfat is intolerant of shade; it decreases as juniper (Juniperus
spp.) cover increases [112].

Winterfat is generally not favored by disturbance.  It had only 4.3
percent cover on formerly cultivated, ungrazed lands, whereas cover was
21 percent on undisturbed sites in Alberta [26].  Winterfat
significantly (p<0.01) increased in desert grasslands protected from
grazing for 10 years in southern Utah [49].  In southwestern Nevada,
winterfat had greater mean density in undisturbed communities than in
communities disturbed by Nevada Test Site activities [36].  Winterfat
was not present on mined sites abandoned from 1 to 13 years previously,
but was present on adjacent unmined plots in northwestern New Mexico
[91].  Although winterfat is susceptible to disturbance, it establishes
on disturbed sites if seeds are present [104].


SEASONAL DEVELOPMENT : 
In the Mojave Desert, winterfat flowers and puts out new growth
following adequate spring, summer, or fall rains [2].  Germination
occurs between October and March after rains of at least 0.6 inch (16
mm) [1].  Bud, leaf, flower, and fruiting phenology is reported for a
2-year period in the Mojave Desert [2].

In Saskatchewan, average first flowering date of winterfat over a 5-year
period was June 27.  The mean flowering period was 45 days [15].  In
western Colorado, flowers bloom in late May to early June [14].  The
average phenology of winterfat in the Curlew Valley in northern Utah
over a 7-year period follows [101]:

Stage				average date

leaf buds swell			April 8
twigs elongate			April 29
floral buds develop		May 28
flowers open			June 7
fruits develop  		July 8
fruit dissemination begins	August 27
summer dormancy begins		September 10

Winterfat root growth was primarily in the upper soil layers early in
the growing season in the Curlew Valley.  Later in the season, root
growth began in the deeper soil layers [33].

Related categories for Species: Krascheninnikovia lanata | Winterfat