BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Halogeton glomeratus | Halogeton 



GENERAL BOTANICAL CHARACTERISTICS : 
Halogeton is an exotic succulent annual forb [42,104].  It has a
generalized type of root system; the taproot can penetrate as deep as 20
inches (51 cm), with a radial spread of 18 inches (46 cm) [32].  Many
main stems branch from the base of the plant and are low spreading
before becoming erect [107].  Halogeton can be a few inches high in
dense stands to 2 feet [61 cm] high in widely spaced stands [103,107].
Leaves are small, fleshy, and spine tipped [26,49].  Flowers are
inconspicuous in leaf axils and produce winged black and wingless brown
seeds [26,101].


RAUNKIAER LIFE FORM : 
   Therophyte


REGENERATION PROCESSES : 
Halogeton can produce 75 seeds per inch (35 seeds per cm) of stem, which
is 200 to 400 pounds of seeds per acre (222-449 kg/ha) [25].  It
produces two types of seeds which are important to its spread and
persistence.  The production of brown seed is controlled by long
photoperiods; black seeds are produced during short photoperiods [114].
Black seeds have no dormancy and are viable for 1 year [24,88,114].
Late germinating and maturing plants only make black seeds [25,114].
Brown seeds have a dormancy and can survive buried for up to 10 years
[4,24,25,108].  This allows halogeton to survive during extended drought
periods.  Brown seeds readily germinated under moist conditions after a
3-month cold (35 degrees Fahrenheit [5.4 deg C]) treatment [24,88].

Halogeton has many agents of dissemination.  Halogeton seeds have a high
degree of viability after passing through the digestive tracts of sheep
and rabbits [24].  Animals are capable of spreading large amounts of
seed great distances; seeds pass with the feces [23,37,63,99].
Halogeton seeds are rapidly spread along roads by road equipment,
especially road graders [24].  Local spread of halogeton is primarily by
the wind [37,99].  Halogeton will break off at ground level when dry and
tumble with the wind, scattering mature seeds [109].  Whirlwinds or
dust-devils will transport dry stems with seeds up to 2 miles (3.2 km)
[24].  Western harvester ants collect seeds [39].  Brown seeds recovered
from anthills gave 5 to 20 percent germination [24].


SITE CHARACTERISTICS : 
Halogeton is adapted to alkaline soils and semiarid environments
[47,107].  Halogeton is found from 2,526 to 7,218 feet (770-2,200 m) in
elevation throughout its range [19,38,43,44].  It occurs on soils that
are heavy clays, clay loams, sandy loams, and loamy sands [5,20,27,50].
Although halogeton can occur on many soil types, the sites usually are
saline [63].  Halogeton does best in soils where sodium chloride levels
are 5,800 p/m; increased salt does not increase the water requirements
of halogeton [25].  Soils may or may not have a prominent hardpan;
carbonates accumulate near the soil surface [16].  Soils are light
colored because little humus is present [50,97].  The soil pH ranges
from 8.0 to 9.0 [27,52].  Typically, there are large fluctuations in
daily temperatures [61].  Mean annual temperature is 42 degrees
Fahrenheit (5.5 deg C).  The abundance of halogeton depends upon year to
year precipitation, so outbreaks may sporadically appear [4,6,103].
Annual precipitation at most halogeton sites is from 5 to 13 inches
(127-330 mm) [21,50].  Approximately, 60 to 70 percent of precipitation
occurs as snow [21,50].

Halogeton has invaded open or disturbed ground such as dry lakebeds and
rodent workings [4,99].  Halogeton infests domestic stock trails,
overgrazed rangeland, and livestock congregation areas [46,49,71,82,86].
Halogeton invaded the disturbed areas left after dryland farms,
townsites, and mining camps were abandoned in the 1930's [25,33,52,56,
109].  Halogeton occurs in railroad rights-of-way, along road shoulders,
airstrips, and gravel pits [61,67,107].

Associated species, in addition to those previously mentioned (see
Habitat Types), are clasping pepperweed (Lepidium perfoliatum),
povertyweed (Iva axillaris), and bur buttercup (Ranunculus testiculatus)
[38,87].  Common grass associates are Indian ricegrass (Oryzopsis
hymenoides) and bottlebrush squirreltail (Elymus elymoides) [44].
Halogeton occurs with Gardner saltbush (Atriplex gardneri) in Colorado
and Wyoming [5].


SUCCESSIONAL STATUS : 
Obligate Initial Community Species

Halogeton is a ruderal species that readily invades disturbed,
saline-alkaline ground where other species offer no or little
competition [37,47,74,77,105,107].  Halogeton does not establish in
vigorous competing vegetation because it does not grow a large shoot or
root system early in the growing season [32].

In the alkaline valley soils where halogeton occurs, shadscale
vegetation is considered an edaphic climax [115].  Human use leads to
permanent changes in the flora of disturbed arid environments [56].
After 70 years of grazing on some sites in the Great Basin, halogeton
was dominant on moderately disturbed areas with cheatgrass and shadscale
[56].  Halogeton may permanently change soil surfaces via salt pumping
which impedes moisture infiltration and enhances evaporation [88,105].
In a comparison of plots on areas that were grazed or protected for 15
years, Branson [17] observed that no succession occurred or that it
occurred very slowly.

Cleared big sagebrush areas follow a succession pattern that currently
climaxes in cheatgrass. Nelson and others [72] state that the succession
through introduced annuals to a cheatgrass climax is maintained by fire.
The order of appearance of vegetation changes are Russian thistle
(Salsola kali), tumblemustard (Sisymbrium altissimum), pinnate
tansymustard (Descurainia pinnata), and cheatgrass [112,116].  Young and
others [116] added halogeton to this sequence as an initial invader.
Halogeton is also a part of another seral continuum that climaxes with
medusahead (Taeniatherum caput-medusae) [116].


SEASONAL DEVELOPMENT : 
Depending upon moisture, halogeton seedlings establish from February
through August, with a peak in April [24,99,101].  Halogeton builds its
root system during the cool weather, and topgrows during warmer weather
[54].  Seedlings begin rapid vegetative growth in May [24,109].  Growth
can continue through June; the best halogeton development occurs when
soil temperatures are between 60 and 80 degrees Fahrenheit (15-27 deg C)
[32].  In Utah, halogeton biomass was 4.1 pounds per acre (4.7 kg/ha)
over 5 years [6].  Near the first part of July, the plants cease
vegetative growth and begin reproductive growth [24].  Plants flower
during July and August.  Seeds begin to mature late August to early
September and are mature in October [24,25,96].  The frosts in October
and November will kill any plants not yet dried [51].  The majority of
black seeds are dropped by early November; however, brown seeds persist
and may remain on the plant until January or February [24].  Black seeds
may germinate after mid-December under favorable conditions [24].
Halogeton is a winter annual in the broad sense; plants may germinate in
the fall, winter, or spring, depending upon soil moisture [92].  Two
authors [96,103] state that halogeton is a warm-season plant; however,
since vegetative growth usually ceases at the end of June and seedling
establishment occurs predominantly in April, Parker [74] considers it a
cool-season plant.

Related categories for Species: Halogeton glomeratus | Halogeton