horsetails

noun

1. The tail of a horse.
2. Any of various simple vascular plants, of the order Equisetales, that have hollow stems and produce spores.
3. A Turkish standard denoting rank.“Commanders were distinguished by the number of horsetails carried before them. The sultan had seven, the grand vizier five, and the pashas three, two, or one.”
4. A mare's tail, a water plant in genus Hippuris.