Other Grasses
A few researchers have studied [189, 144, 190] other fast growing prairie grasses as cellulosic ethanol feedstocks, some of these varieties include:
1. Big Bluestem (Andropogon gerardii), also known as turkey foot, prairie tall grass, or simply tall grass, is a tall grass native to much of the Great Plains and prairie regions of Central North America. This grass is tolerant to a wide range of soils and moisture conditions. Depending on soil and moisture conditions, it grows to a height of 1-3 meters (3.3-9.8 ft). In a comparison of big bluestem grass with little bluestem grass and other varieties of warm-season grasses [191], big blue — stem grass has shown the highest concentration of cellulose. In this study, it was found that four warm — season grasses, big bluestem (Andropogon gerardii), little bluestem (Schizachyrium scoparium), prairie sand reed (Calamovilfa longifolia), and switchgrass (Panicum virgatum) had cellulose contents of 346, 342, 340 and 338 g kg-1, respectively. Further, it was reported that accumulated thermal time (degree day base 10°C) correlated to hemicellulose concentrations in the warm — season grasses but not for cool-season grasses.
2. Indian grass (Sorghastrum nutans) is another native warm-season perennial grass species in the North American tall grass prairie ecosystem with potential as a bioenergy crop [144, 189].
3. Timothy grass (Phleum pratense) is an abundant perennial grass native to most of Europe except for the Mediterranean Region. It grows to 50-150 cm tall, with leaves up to 45 cm long and 1 cm broad. The flower head is 7-15 cm long and 8-10 mm broad, with densely packed spikelets. Timothy grass was unintentionally introduced to North America by early settlers [192]. A study on saccharification of pretreated timothy grass at two different stages of maturity and ethanol yields produced by fermentation with Saccharomyces cerevi — siae was reported in 1997 [193].
4. Tall fescue grass (Festuca arundinacea; syn., Lolium arundinaceum) is a fast growing species with potential as a bioenergy crop [192]. It is a cool-season perennial C-3 species of bunchgrass native to Europe.