\Quill"wort`\, n. (Bot.)
Any plant or species of the genus {Isoetes}, cryptogamous
plants with a cluster of elongated four-tubed rushlike
leaves, rising from a corm, and containing spores in their
enlarged and excavated bases. There are about seventeen
American species, usually growing in the mud under still,
shallow water. So called from the shape of the shape of the
leaves.