(Oxycaryum, Bolboschoenus, and Schoenoplectus)

Treated by some authors all as species of Scirpus, the Flora of North America classification is as follows:

1. Saltwater species. Culms with durable corms, scabrous marginally; culms with some cauline leaves or nodes; leaf blades eligulate; achenes inflated and floating...Bolboschoenus robustus

1. Plants in freshwater (S. tabernaemontanii may be in brackish water); culms leafless; leaf blades ligulate; achenes not inflated...2

2. Plants stoloniferous and not clumped; stems triangular with a cluster of rays at the top (reminiscent of Cyperus); ligule ciliate; flowering heads globose; achene encased in a white bonelike material... Oxycaryum cubense (an introduced weedy species)

2. Plants clump-forming or rhizomatous with round or triangular leafless stems; ligule membranous; achene not encrusted in white material...Schoenoplectus...3

3. Culm mostly round (possibly triangular toward the apex); inflorescence branched...4

3. Culm strongly triangular; inflorescence unbranched, capitate...5

4. Perianth parts 2-4, flattened; leaf blades < 2 cm or absent; stem triangular toward the top...S. californicus

4. Perianth parts 6 bristles; leaf blades generally > 2 cm; stem rounded at the top (spikelets often orangish and spotted)...S. tabernaemontani

5. Notch in scales < 0.5 mm; awns mostly < 0.6 mm; distal leaf blade usually shorter than the sheath; culms strongly triangular, the sides often deeply sulcate; bracts without blades (resembling scales)...S. americanus

5. Notch in scales > 0.5 mm; awns mostly > 0.5 mm; distal leaf blade usually longer than the sheath; sides of culm flat or shallowly concave; bracts with blades...S. pungens