pillwort

Century Dictionary and Cyclopedia

1. n. A plant of the genus Pilularia; especially, P. globulifera, the creeping pillwort of Europe: named from the pellet-like involucres containing the fruit.

Wiktionary

1. n. botany Any plant of the genus Pilularia; a minute aquatic cryptogram with small pill-shaped fruit.

GNU Webster's 1913

1. n. (Bot.) Any plant of the genus Pilularia; minute aquatic cryptograms, with small pill-shaped fruit; -- sometimes called peppergrass.

WordNet 3.0

1. n. European water fern found around margins of bodies of water or in wet acid soil having small globose sporocarps