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Friday, August 26, 2011

Grasslands of the High Plains

Here's Joy Handley of WYNDD (right in the blue plaid),
showing a group of Wyoming science teachers
around the Rocky Mountain Herbarium at the
University of Wyoming.
You remember Joy, right?  She's a botany pro at WYNDD with a love for sedges and grasses.  She wrote the article about the Berry Prairie's token sedge species earlier this month. 

Today, Joy is sharing her knowledge about grasses - specifically those that are found in the Berry Prairie.  Email THuja@uwyo.edu with questions or for additional information.

There is also a grasses key available for you to use while you're walking through the Berry Prairie.  The key was put together by Emma Stewart, a master's student in Botany and former intern at WYNDD.  The key will help you identify which grass species is which.


Berry Prairie Grasses:

Due to a great deal of research into species’ relationships in the grass family (Poaceae) over the last few decades, there are many species with several scientific names (synonyms). Of the species on the Berry Center Green Roof, western wheatgrass is an example of this phenomenon; it is known as Pascopyrum smithii, Agropyron molle, Agropyron smithii, Elymus smithii, and Elytrigia smithii. Indian ricegrass has a slightly shorter list of synonyms: Achnatherum hymenoides, Oryzopsis hymenoides, and Stipa hymenoides. For the most part, the rest of the grasses on our green roof have been known by the same scientific names for a long time: blue grama (Bouteloua gracilis), sideoats grama (Bouteloua curtipendula), prairie Junegrass (Koeleria macrantha), prairie dropseed (Sporobolus heterolepis), and little bluestem (Schizachyrium scoparium). Sandberg bluegrass (Poa secunda) was once divided into seven separate species but the overlaps in morphology and lack of barriers to hybridization caused it to be put into one, highly variable, species.

Western Wheatgrass is a very common species in Wyoming prairies.


The grass species on the Berry Green Roof, and the Laramie Basin in general, have an array of life strategies to survive on the High Plains. Western wheatgrass reproduces vegetatively with underground stems (rhizomes). This method of producing “clones” allows the grass to spread relatively quickly in an area of suitable soil to supplement unpredictable circumstances for sexual reproduction. The other species have varying amounts of cespitose growth habit, meaning they tend to grow in bunches, mats, or tussocks. Bunchgrasses clone themselves slowly outward; sometimes the older inner portions of the bunch will die off leaving a ring of genetically identical bunches. The tuft of a bunch grass are often able to survive fire, the outer portion of the bunch may burn hot enough to be killed, while the inner portion is insulated enough to resprout.


Grasslands just west of Laramie. 
Photo courtesy of jimmywayne

The Wyoming Plains have a short, cool but semi-arid growing season. There are two different photosynthetic pathways that give different grass species special advantages in diverse environments. The C3 pathway is the most common in the plant world and is most beneficial in cool, moist ecosystems. Green roof species that utilize C3 carbon fixation, and are known as cool season grasses, include western wheatgrass, prairie Junegrass, Indian ricegrass, and Sandberg bluegrass. C4 carbon fixation provides greater water use efficiency and is more favorable in hot, dry settings. The C4, or warm season grasses on the green roof are blue grama, sideoats grama, prairie dropseed, and little bluestem.

Written by Joy Handley, WYNDD

 

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