Crossword clue: any unbranched, slender, green plant of the fresh-water algae. the word is frequently used in a wider sense.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
any of various algae of the genus Tribonema; algae with branching filaments that form scum in still or stagnant fresh wa