PILLWORT
pillwort, Pilularia globulifera
(noun) European water fern found around margins of bodies of water or in wet acid soil having small globose sporocarps
Source: WordNet® 3.1
Etymology
Noun
pillwort (plural pillworts)
Any plant of the genus Pilularia, a minute aquatic fern with small pill-shaped sporangia.
Synonyms
• peppergrass
Source: Wiktionary
Pill"wort`, n. (Bot.)
Definition: Any plant of the genus Pilularia; minute aquatic cryptograms,
with small pill-shaped fruit; -- sometimes called peppergrass.
Source: Webster’s Unabridged Dictionary 1913 Edition