"horsetails" in the noun sense
1. horsetail
perennial rushlike flowerless herbs with jointed hollow stems and narrow toothlike leaves that spread by creeping rhizomes tend to become weedy common in northern hemisphere some in Africa and South America
Source: WordNet® (An amazing lexical database of English)
Princeton University "About WordNet®."
WordNet®. Princeton University. 2010.
View WordNet® License