mare's-tail

noun5

1. •
   A long streaky cloud, spreading out like a horse's tail, and believed to indicate rain; a cirrus cloud.
2. •
   Any aquatic plant of the genus Hippuris, having narrow leaves in whorls.
3. •
   especially, common mare's tail (Hippuris vulgaris)
4. •
   Equisetum, a fern ally.
5. •
   Erigeron canadensis (syn. Conyza canadensis), an annual weed.