hare's-tail

from The Century Dictionary.

• noun A species of cotton-grass, Eriophorum vaginatum, common in Europe and North America.
• noun The hare's-tail grass (which see, under grass).

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A kind of grass (Eriophorum vaginatum). See Cotton grass, under cotton.
• noun (Bot.) a species of grass (Lagurus ovatus) whose head resembles a hare's tail.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany A kind of grass (Eriophorum vaginatum).