threesquare /ˈθɹiːskwɛə(ɹ)/ noun3 •Several species of bulrush (biologically, sedges) with a triangular stem. •Schoenoplectus americanus (American threesquare, Olney's bulrush, chairmaker's bulrush).In colonial days, threesquare was used to cane chair seats. — 2018 •Schoenoplectus pungens (common threesquare, sharp club-rush)
