Degree Name

Master of Science (MS)

Semester of Degree Completion

2014

Thesis Director

Gordon C. Tucker

Abstract

Two closely related species of bulrush, Scirpus atrovirens (Green bulrush) and Scirpus georgianus (Georgia bulrush), are widely distributed in Illinois. They are difficult to separate in the field, but readily distinguishable under magnification in the lab. These two species have been found in moist meadows, shallow marshes, edges of wet forests, and ditches. The objective of this study was to evaluate the morphological and ecological distinctness of the species with the aim toward discovering and describing other features to distinguish them reliably. Eighty plants of Scirpus atrovirens and 80 of Scirpus georgianus were examined. Fifty S. atrovirens and 50 S. georgianus were collected in the field at different counties in Illinois. Thirty S. atrovirens and 30 georgianus specimens were measured from Stover-Ebinger Herbarium at Eastern Illinois University in Charleston, IL, University of Illinois in Champaign herbarium, and the Morton Arboretum in Lisle, IL. Parameters measured on both species were spikelet length/width (mm), culm width (mm), rachilla length (mm), scale length/width (mm), plant height (cm), and achene length/width (mm). A t-test performed showed a significant difference between the species in spikelet length and width, rachilla length, scale length and width, culm width, and achene length and width. There was no significant difference in plant height. Scirpus atrovirens was larger in several morphological characteristics than S. georgianus. Analysis of field data showed that within 30 m of S. atrovirens, 61 different plant species were found. Thirty-four different plant species were found within 30 m of S. georgianus. Only five plant species were found within 30 m of both S. atrovirens and S. georgianus: Glyceria striata, Phalaris arundinacea, Agrostis alba, Juncus dudleyi, and Carex lupulina. Soil data was examined for numerous collections sites. Seventy- nine percent of Scirpus atrovirens examined occurred in silty loam, while 88% of Scirpus georgianus examined occurred in silty loam. There were 31 families that were found within 30 m of S. atrovirens, and 16 families that were found within 30 m of S. georgianus. Poaceae had the highest percentage (29%) of plant species found within 30 m of S. georgianus. Cyperaceae had the highest percentage (24%) of plant species found within 30 m of S. atrovirens. Herbaceous perennials had the highest percentage (51%) of each type of plant species found within 30 m of S. atrovirens. Herbaceous perennials had the highest percentage (76%) of each type of plant species found within 30 m of S. georgianus. Native species had the highest percentage (90%) present compared to non native species (10%) of plant species found within 30 m of S. atrovirens. Native species had the highest percentage (85%) present compared to non-native species (15%) found within 30 m of S. georgianus. The Sorensen Index was used to measure the similarity in communities between S. atrovirens and S. georgianus. The Sorensen Index between the aggregate communities around each of the two species was 0.3. The Sorensen Index of 0.3 from this study indicates that the plant community was significantly different between the two species. Scirpus atrovirens and Scirpus georgianus are different from each other morphologically and ecologically.

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