Salt Playa Food Web 
Plants of the Playa 
iodine bush 
Allenrolfea occidentalis
 
Photo provided by Arizona State University Herbarium  http://ls.la.asu.edu/herbarium/images 

What is iodine bush?  
What does iodine bush Look Like?  
Where does iodine bush live?  
How can it live in the playa's extreme environment?  
What is iodine bush's role in the food web?  
References  
 
  What is iodine bush? 
Allenrolfea occidentalis is in the Chenopodiaceae or Goosefoot Family.  This plant has many common names such as iodine bush, bush pickleweed, or kern greasewood.  The name iodine bush was probably given to this plant because when you crush its leaves, a brown color emerges.  This genus is named for the botanist Allen Rolfe from Kew Gardens in London around early 1900's (Mozingo 1987).  

Many members of this family are halophytes.  That means they are tolerant of extreme environments  in which other plants can not survive.  This particular species is tolerant of soils that contain an appreciable amount of salt.  Iodine bush grows in moist places, some of which are so saline that no other plant can tolerate the habitat.(Anderson 1986).  Since they can tolerate high concentrations of salt in the soil, they play a vital role in many parts of the world such as the coasts of the Mediterranean, Caspian and Red seas, the flora of the steppes of Central Asia as well as the alkali plains of the SW U.S.(deWit 1966).  Members of this family grow as weeds in "saline soils near human habitations and especially bomb sites"(deWit 1966). 

What does iodine bush look like? 
 
Shrub  Photo provided by Arizona State University Herbarium  http://www.ls.la.asu.edu/herbarium/images  

This shrub is rarely more than 4 feet tall ranging from between 30 centimeters and 1 meter high(Mozingo 1987).  A low, straggly branching woody shrub that has round, succulent, gray-green, jointed stems that ascend from a woody root.  Its name probably comes from the salty-bitter iodine taste of its saltwater-filled tissue.  It has distinctive succulent green segments along the stem arranged in a chain, much like miniatur sausages (Harrison 1993).  Iodine bush leaves are reduced and scale-like.  Its older branches turn dark purplish brown.  The stems have an interesting tart, salty flavor.  Inconspicuous flowers are produced on short scaly spikes(Anderson 1996).  

Iodine bush is similar to the annual pickleweed and inweeds in appearance. The difference between the two is that pickleweed has leaves that are opposite on the stem while Iodine bush has alternate leaves wiht a distinctive opposite branching pattern. Also, iodine bush is a shrub not a solitary plant as is pickleweed.  The woody stems branch alternately which distinguishes it from the annual pickleweed which has  and must reproduce from seed each year. Iodine bush will tolerate salt up to 3-4%, but it grows best in 1-1.5% in a zone with a reliable supply of water (Harrison 1993). 
 
Where does iodine bush live? 
Habitat for Allenrolfea occidentalis 

Extensive stands of iodine bush can be seen in the desolate saline areas west of Salt Lake City, where it usually occupies low hummocks on the salt flats. Allenrolfea is directly responsible for the formation of these hummocks by capturing windblown sand. Iodine bush produces underground runners which assist in its spread(Mozingo 43 1987).  

The [geographic] range of iodine bush includes California, east to Colorado, New Mexico, and western Texas, and south into northern Mexico. It is abundant on the alkaline flats of southern and northern nevada and extends northward to eastern Oregon(Mozingo 1987). 
The figure below shows the distribution of iodine bush in Utah by county.  

 
Map provided by Utah State University Geography Department 

How can iodine bush live in such an extreme environment? 
As noted by Mozingo 1987, Allenrolfea occidentalis is one of the most common plants on  the Great Salt Lake Playa.  Iodine bush utilizes the plant's ability to export salt from its tissues into the cells interior vacuole as it absorbs salt through its roots from the soil.  Salt diffuses rapidly into the roots from the salt playa's soil.  This plant must actively use the cells natural ability to export salt by the sodium - potassium ion pump exchange mechansims that exists in all cell membranes.  This activity requires a lot of energy that the plant gets from the sun by photosynthesis.  Through the process of photosynthesis, the chloroplasts within the plant's tissues transforms the suns energy into the plants energy which is in the form of Adenosine-Tri-Phosphate or (ATP). 

There have been many studies on Allenrolfea occidentalis to determine how this plant has adapted to live in its high saline environment.  The following experiments have tried to explain how this plant has been studied because of its unique adaptation to its environment.  Like many of the plants and animals that also live on the Great Salt Lake Playa, they have adapted by the process of natural selection to be tolerant of excess salt content in the water and the soil.  Gul Bilquees and Darrell Weber of BYU in  Utah 1998, studied how salt effects seed germination on iodine bush.  Another study was conducted in 1988 by Chrominski, Halls, Weber, and Smith also at BYU studying how iodine bush deals with the excess salt in its tissues.  

What is iodine bush's role in the food web? 
Because of the extremely salty nature of the salt-succulent stems, few animals graze directly on iodine bush.  But just because animals don't eat the actual plant, many do eat the seeds that the plant produces.  Examples of these plants are mentioned in other pages in this project their links are here:  
 VOLES and Savannah sparrow. 

REFERENCES 
Anderson, Bernice A. 1996 Desert Plants of Utah  Utah State University pp.21 

Chrominski A., Halls S., Weber, D.J., Smith B.N. 1988 "Proline affects ACC to Ethylene Conversion under Salt and Water Stresses in the Halophyte Allenrolfea occidentalis"  Department of Botany and Range Science, BYU Provo, Utah. 

Gul, Bilquees, and Weber, Darrell J 1998 "Effect of dormancy Relieving Compounds on the Seed Germination of Non-dormancy Allenrolfea occidentalis under Salinity Stress"  Department of Botany and Range Sciences, BYU Provo, UT. 

deWit, H.C.D. 1966  Plants of the World E.P. Dutton and Co., Inc.  Netherlands, New York. pp. 202-205 

Harrison, A.T. 1993.  The Salty Shore of Great Salt Lake:  A Natural History.  Unpublished. 

Mozingo, Hugh N, 1987  Shrubs of the Great Basin.  A Natural History  University of Nevada Press, Las Vegas, Nevada    pp 43-45. 

Nelson, Ruth Ashton, 1969  Handbook of Rocky Mountain Plants  Dale Stuart King, Pub. Tuscon, Arizona. pp. 113 

Waisel, Yoav. 1972 Biology of Halophytes  Ed. by T.T. Kozlowski, University of Wisconsin, Madison. 

Utah State University Geography Department online,  http://www.nr.usu.edu/Geography-Department/ utgeog/utvatlas/family/chen/aloc2.html (November 1999) 

Arizona State University Vascular Plant Herbarium (1997, Revised August 31, 1999) <http://ls.la.asu.edu/herbarium/images/chen/allocc2.jpg> (November 1999) 
<http://ls.la.asu.edu/herbarium/images/cheno/allocc1.jpg> (November 1999) 

CREATED BY PAIGE WALKER  
COMPLETED 12/6/99 

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