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SOME PROMISING CHENOPODS FOR USE ON DISTURBED LANDS
Howard C. Stutz
ABSTRACT: Some of the harshest sites in western
North America are occupied solely by members of
the family Chenopodiaceae. Because of the
abundant genetic variation present in many of the
species, there is good opportunity for deliberate
breeding and selection of superior forms. This
is particularly true of Atriplex which has
experienced an explosive evolution during recent
years, yielding numerous forms uniquely adapted
to specific sites.
Of these, Atriplex is the only one in which there
has been an explosive eruption of species. Each
of the other genera only have one or two species
as follows:
CERATO IDES
£·
~ (winterfat) is a highly variable
species but primarily at the genic level; all, so
far examined, are diploid except one population
of tetraploids in central Colorado. Winterfat
grows throughout all of western North America from
Alaska to Mexico. Some forms grow to more than
three feet (one meter); most are less than one
foot (30 em) tall.
INTRODUCTION
Thousands of acres of salt desert in western
North America are occupied solely by plants
belonging to the family Chenopodiaceae. In some
places the Chenopod landscape is small -- on the
order of one hundred acres (40 ha) or less. More
often it is so extensive that one can travel all
day by automobile without seeing anything but
Chenopods. In total, more than 300 million
acres (120 million ha) in western North America
are dominated by these remarkable plants.
Because of its extensive genetic variation,
potential for improvement by breeding is very
promising.
GRAYIA
G. brandegei is narrowly distributed in southern
Wyoming, western Colorado, southeastern Utah and
northeastern Arizona. It is found almost
exclusively on talus and steep mud slopes.
Variations in stature and leaf size are dramatic
but no genetic studies have yet been made to
disclose the bases for these or other
differences. So far, only diploid chromosome
numbers have been found.
The reasons for the superior performance of
Chenopods are not well known but must include
attributes which permit accommodation of both
climatological drought resulting from low levels
of precipitation, and physiological drought
caused by high salt content of soils. Some
species excrete salt externally on the surface of
leaves (Osmond and others 19£0; Mozafar and
Gooden 1970; Hill and Hill 1976). Some adjust
by increasing succulence (Black 1958) • Some
species circumvent challenges by becoming dormant
during periods of stress. Some apparently obtain
physiological advantages from saline environments
(Ashley and Beadle 1957; Caldwell 1974).
Grayia brandegei is very different from G.
~a but very much like Zuckia arizonTca and
therefore would probably best be changed to
brandegei.
G. spinosa (Hook.) Moq. (Spiny Hop-sage) is an
Important range plant throughout much of Utah,
Nevada, Colorado, Idaho, Wyoming and eastern parts
of California, Oregon and Washington. Variations
expressed between natural populations suggest
promise for improvements by breeding and
selection.
There are seven principal genera of perennial
Chenopods in western North America: Atriplex,
Ceratoides, Grayia, Kochia, Sarcobatus, Suaeda
and Zuckia. - - - - - Genus
Atrip~
Ceratoides
Grayia
KOCiiia
~atus
Suaeda
ZiiCkia
z.
Species
more than 20 named species and at
least that many more to be yet
named
c. 1anata
G. brandegei, G. spinosa
K. americana
s. vermiculatus, s. baileyi
s. fruticosa
~- arizonica
KOCHIA
K. americana Wats. (Green Molly) is usually
~onsidered to be the only perennial species of
Kochia in North America although some authors
~ize K. californica as a distinct species
with smaller leaves and more spreading habit. K.
americana occupies extremely harsh environmentswhich are usually dry and alkaline. It is
apparently quite uniform genetically and hence
not amenable to much improvement by genetic
manipulation.
Howard C. Stutz is Professor of Botany and
Genetics in the Department of Botany and Range
Science, Brigham Young University, Provo, Utah.
132
SARCOBATUS
widely spaced bushes with very little else growing
with it. It appears to be genetically quite
uniform so probably offers little promise for
development for use on other sites.
~·
baileyi Cov. grows only in western Nevada and
east-central Utah. It is generally not listed as
an important range plant but because of its
capacity to accommodate severely harsh
environments, it deserves more consideration. It
occurs in almost pure stands, sometimes covering
thousands of acres, on dry gravelly soils. It
appears to express very little genetic variation
so may be unsuited for much genetic improvement.
ATRIPLEX
Atriplex is so genetically rich and
evolutionarily explosive, it is difficult to
become acquainted with the component species
except within an evolutionary and genealogical
context. Although much is yet to be studied
before a completely valid interpretation can be
formulated, it is possible, from what we do know
to identify some highly probable biogeographical
history to accommodate most of the.recognizable
variations.
s. vermiculatus (Hook.) Torr. (Greasewood) is a
highly variable species growing mostly in
bottomlands in heavy clay soils but often extends
up even steep hillsides, particularly where there
is seepage and/or saline soils. It is endemic to
western United States and Canada. It is most
abundant in the Great Basin but extends northward
to southern Alberta and eastern Oregon and
Washington, and southward to Arizona and Texas.
Two chromosome races (4N and 8N) have been
detected thus far but have not been shown to be
correlated with morphology nor ecological
preference. Although generally considered a
nuisance plant in some areas, it is sometimes
highly prized for forage, particularly where it is
associated with other species which provide
dietary variety.
It appears that during the Pleistocene, Atriplex
canescens (four-wing saltbush) existed in the
diploid form throughout much of the southern
Mojave and northern Sonoran deserts. Tetraploids
were most common east of the Rockies in what was
probably an ice free corridor. Following the
demise of Pleistocene Lakes 10-12,000 years ago,
tetraploid forms derived from the warm desert
diploids migrated northward into the Great Basin
and other intermountain terrain. This northward
migration is apparently still in progress and can
be witnessed at several advancing fronts. It (4N
A, canescens) has arrived at Pocatello, Idaho but
not at Blackfoot nor Idaho Falls. It has marched
to the Snake River near Boise, Idaho but has only
rarely crossed it. It is at Marsing, Idaho and
Ontario, Oregon, but not yet to Weiser.
SUAEDA
S. fruticosa (L.) Forsk (seepweed) is common in
moist saline bottomlands throughout western North
America from Alberta to Mexico and also
throughout much of Europe and the Middle East.
Some authors have referred to the American form
as~· torreyana Wats., but there appears to be no
consistent differences which will delineate it
from the old world form. There is considerable
variation within the species, particularly in
habit and in edaphic restrictions. Most plants
are 15-30 inches (38-76 em) at maturity but some
have been reported at more than 6 feet (2 meters)
in height, while other populations consist of
plants which are no more than 8 inches (20 em)
in height. Most grow on heavy clay soils but
many populations occur on sands.
These tetraploids which have just recently
migrated northward to occupy much of New Mexico,
Arizona, Utah, Nevada, California, southern
Oregon, southern Idaho and western Colorado
appear to be genetically distinct from the more
ancient forms which reside east of the Rockies.
During their northward migration, A. canescens
came in contact with other Atriplei species with
which it has hybridized to produce numerous new
adaptive products which are now expanding to fill
unique habitats. Among the most fruitful of these
interspecific hybrids have been A. canescens x A.
tridentata, A. canescens x A. falcata and A.
canescens x ~- polycarpa.
-
Very little attention has been given to the
genetics of Suaeda but because of its abundance
inherent genetic variation, it should be possible
to prepare genotypes which would be suitable for
use on many range sites.
A. canescens east of the Rockies hybridized with
gardneri to give an array of hybrid products
collectively referred to as ~· aptera ("Wytana"
saltbush is one of these products).
A.
ZUCKIA
Another important species which has had
phenomenal success since the disappearance of the
Pleistocene lakes is A. confertifolia
(shadscale). During the Pleistocene it apparently
existed in the diploid form throughout much of
the Intermountain West, above the lakes and
northeast of the montane glaciers in ice-free
tablelands. With the disappearance of the lakes,
tetraploid forms derived from the resident
diploids spreaa into the E%pty vallcy~. as irnmePse
z.
arizonica Standl. has until recently been
thought to be endemic to northwestern Arizona but
it is also common in many parts of Utah. It has
apparently escaped attention because of its
superficial resemblance to Grayia brandegei. It
has also been collected and deposited in herbaria
as Atriplex. However it is a very distinctive
species and because of its tolerance of extremely
harsh environments deserves our attention. It is
found mostly on shallow sandy soils as scattered,
133
monoculture populations, occupying the vast
domains left exposed as the waters receded.
Octoploids and decaploids followed, also
occupying extensive acreages left exposed as the
lakes dried up.
western North America. In the Colorado River
drainage of eastern Utah and western Colorado a
number of unique diploid species have combined in
various combinations to produce new highly
adaptive taxa. Also chromosome races of many
species have emerged in response to major
ecological variations.
Hybridization of A. confertifolia and A.
canescens has pro~ided introgressant p~pulations
having improved genetic capabilities but no
distinct taxon has yet been found.
In eastern Utah and western Colorado tetraploid
Atriplex cuneata appears to have arisen several
times as an allopolyploid from different
combinations of various diploid species as well as
an autopolyploid from ~- ancestrale sp. nova. A.
corrugata occurs here also in both diploid and
tetraploid forms.
While A. canescens was migrating from the south
and ~.-confertifolia was expanding into newly
exposed domains, a battery of other Atriplex taxa
were entering this same arena from the north. A.
canadensis sp. nov., a common diploid species in
Alberta and Saskatchewan, apparently gave rise to
at least three other distinct taxa: A. falcata,
A. gardneri and A. tridentata. Each ;f these
grade almost imperceptably into A. canadensis but
separate neatly into distinct entities as they
move further and further south.
In the southern deserts, mostly south of 37°
latitude, several other Atriplex species dominate
many areas. A. obovata is common throughout
Arizona, New Mexico, Chihuahua and Sonora.
Although of lower palatability than most other
species of Atriplex, it is a highly important
range plant, partly because in many places it is
almost the only species which can accommodate the
harsh, warm, saline deserts. In some respects it
is the southern counterpart of A. tridentata to
the north in that it is an upright subshrub, a
vigorous root-sprouter and grows mostly in heavy
clay soils.
~-
falcata occurs mainly as a diploid form
throughout southern and eastern Oregon, southern
Idaho, southern Wyoming, western Utah and much of
Nevada. It usually occurs in monoculture
populations of ca 5 to 30 acres (2 to 13 ha) on
sandy loam soils. Sharp contact boundaries
usually separate it from Artemisia tridentata,
Ceratoides lanata, Sarcobatus vermiculatus or
other speci~Atriplex. Although mostly
diploid, both tetraploid and hexaploid forms are
also known.
Hybrids between A. obovata and A. canescens are
not common but when they do occur, hybrid swarms
and segregating backcross progeny are common.
Some of these have proven to be very valuable in
use on mine spoils in northern New Mexico.
~-
gardneri is abundant throughout Wyoming,
Montana, and North and South Dakota west of the
Missouri River. It occurs mostly in the
tetraploid form'although diploids are quite
common, particularly on harsher sites.
Throughout much of its territory A. gardneri
contacts and hybridizes with A. canescens
yielding, in many instances, the hybrid
derivative ~- aptera.
A. polycarpa is one of the most drought tolerant
of all Atriplex species. It is common throughout
the Mojave Desert and down into many parts of
Mexico including most of Baja California. Its
interest to range managers to the north comes from
its. potential for increasing drought tolerance in
cold tolerant species. In many places it
hybridizes rather freely with A. canescens
yielding fertile hybrids and hybrid segregants.
An important derivative from these hybrids is A.
laciniata, a remarkably promising species found in
many,places throughout the Mojave Desert.
A. tridentata occurs as diploids, tetraploids and
hexaploids but it is only at the hexaploid level
that it has been phenomenally successful. This
is the form which occupies thousands of acres of
the saline bottomlands of old Lake Bonneville.
It is a vigorous root-sprouter which may account
for some of its success in competing for these
rich, albeit saline, territories. Its contact
and subsequent hybridization with A. canescens
has yielded several new exciting hybrid
derivatives. Hybrids with A. confertifolia are
also common, and although less conspicuous than
those derived from hybridizing with A. canescens,
may be responsible for some of its e~tensive
variation and also perhaps for some of the
variation found in A. confertifolia.
There are several other important, well known
species of Atriplex in western North America and
they too demonstrate the unusual propensity for
rapid evolution and hence the promise for almost
unlimited opportunity for improvement through
breeding and selection. Because most species of
Atriplex are available in several chromosome
races, readily hybridize with others upon contact
and are mostly cross-pollinated, their genetic
base is phenomenally rich. They are remarkably
adapted to accommodate almost all of the existing
challenges presented by the deserts of western
north America and because of their rich genetic
heritage can provide new permutations suitable
for accommodating almost any conceivable new
challenge. Probably no other group of plants
could offer more potential for genetic
manipulation.
Besides this evolutionarily explosive eruption of
Atriplex in the Great Basin brought about by the
intermingling and hybridization of taxa which
recently migrated in from both the north and the
south, together with those which were already
resident, other forms have evolved elsewhere in
B4
PUBLICATIONS CITED
Ashby, W. C.; Beadle, N. C. W.
Studies
on halophytes III. Salinity factors in the
growth of Australian saltbushes. Ecology
38: 344-352; 1957.
Black, R. F. The effect of sodium chloride on
leaf succulence and area of Atriplex hastata
L. Aust. Jour. Bot. 6: 306-321; 1958.
Hill, A. E.; Hill, B. s. Elimination processes by
glands: mineral ions. In Luttge, U.; Pitman
M.G., eds. Transport i~plants II.
Encyclopedia of plant physiology II B.
New York:
Springer Verlag; 1976
480 p.
Mozafar, A.; Goodin, J.R. Sodium and
potassium interactions in increasing sal$
t~lerance of Atriplex halimus L.
II. Na and
K uptake characteristics. Agron. Jour.
62: 481-484; 1970.
Osmund, c. B.; Bjorkman, 0.; Anderson, D. J.
Physiological Processes in Plant Ecology:
toward a synthesis with Atriplex.
New York: Springer Verlag; 1980. 468 p.
f.·'
135