Unlike crested wheatgrass, an alien species from Siberia that forms only shallow roots and produces tall above-ground shoots, native North American grasses develop an extensive root system, allowing for greater enrichment of the soil, but do not grow to be very tall.

• Anative North American grasses develop an extensive root system, allowing for greater enrichment of the soil, but do not grow to be very  
• Bnative North American grasses develop an extensive root system, which allows for their greater enrichment of the soil, but without growing to be that  
• Cthe root system of native North American grasses is extensive, allowing for greater enrichment of the soil, but they do not grow to be very  
• Dthe root system of native North American grasses is more extensive, allowing for the greater enrichment of the soil, but these grasses do not grow to be very  
• Ethe extensiveness of the root system of native North American grasses allows for their greater enrichment of the soil, but they do not grow to be that