Group 1. Plants with upright or upslanted leafless stems; or similar plants with long, narrow leaves coming from the lower part of the stems; flowers usually individually inconspicuous, but crowded and numerous. pp. 5-22
Group 2. Plants with upright or upslanted stems with grass-like leaves on two sides (one plane); flowers individually inconspicuous between scales which overlap in two rows to form spikelets, the spikelets clustered toward the top of stems. pp. 23-36
Group 3. Plants with upright stems with grass-like leaves on three sides; flowers individually inconspicuous between scales which usually overlap in several rows to form spikelets, the spikelets clustered toward the top of stems. pp. 37-45
Group 4. Plants with upright, sprawling, or horizontal stems with singly placed, non-grasslike, lance-shaped or wider, untoothed leaves; flowers clustered at the end of stems or single or clustered at the base of leaves. pp. 46-55
Group 5. Plants with upright, sprawling, or horizontal stems with paired, whorled, or otherwise clustered, lance-shaped or wider, untoothed leaves; or plants with leafless stems and paired or whorled branches; flowers single or clustered at the end of stems, in stalked heads along stems, or single or clustered at the base of leaves. pp. 56-69
Group 6. Plants with both their lance-shaped or wider, untoothed leaves and the stalks of their solitary flowers or flower clusters coming from underground stems or underwater sterms. pp. 70-86
Group 7. Plants with tooth-edged to deeply divided leaves or leaflets. pp. 87-94