Marestail (also mare's tail and mare's-tail) may refer to:
Plants
- Conyza canadensis, an annual weed also known as horseweed and Canadian fleabane
- Equisetum, a fern ally also known as horsetail and pipeweed
- Hippuris, a genus of aquatic flowering plants, including:
- Hippuris vulgaris, the common mare's-tail
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;Waterfalls
- Mare's Tail, on the Snaid Burn near Loch Lomond
- Mare's Tail, on Hungry Hill in Ireland
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Other
- Mare's tail, a type of cirrus cloud formation
See also
- Grey Mare's Tail (disambiguation)