Hippuris vulgaris aka Mare's Tail

Hippuris vulgaris, or common mare’s tail, is an aquatic perennial. It belongs to the plantain family, Plantaginaceae. Its native range spans subarctic and temperate regions. It is native to Britain and Ireland. Other names include bottlebrush, jointweed and paddock pipes. It grows along pond margins and in ditches. It also lives in marshes, shallow lakes and slow streams. These sites may have muddy or peaty shores.

Straight, hollow stems rise from rhizomes beneath the water. Narrow green leaves grow in close whorls around each stem. This gives the shoots their brush-like shape. The soft foliage stands upright above the water. The plant loses its leaves at the season’s end. RHS describes leafy stems reaching about 1 foot [0.3 metres]. Its garden size range is 0.3–1.6 feet [0.1–0.5 metres] in height and spread. Plants reach full size within one to two years. Small green-yellow flowers may appear during summer. The leaves and stems give more visual interest than the flowers.

Grow it at a pond edge or in a bog garden. It accepts full sun or some shade. RHS lists clay soil and a broad tolerance of soil pH. The crown can sit beneath about 0.5 feet [0.15 metres] of water. Plant it straight into the pond edge or use a basket. Aquatic compost with a gravel top layer suits basket planting. RHS rates its cold hardiness H7. Plants For A Future lists USDA zones 3–10.

The upright shoots contrast with floating leaves and low waterside plants. This makes it useful in wildlife ponds and water gardens. Rhizomes can spread, so small ponds may need a planting barrier. A submerged basket can help keep growth within bounds. Divide established plants to make more. RHS lists no need for pruning. It also reports few routine pest or disease problems. These traits make it a low-maintenance choice where conditions suit it.

Plants For A Future lists leaves, young shoots and tender upper stems as edible. Cook them before eating; boiling is the safer preparation. Young green tops are softer than the older lower stems. Use only plants from water known to be clean. Water that looks clear may still contain germs, parasites or pollutants. These risks differ from any toxic effect of the plant itself. The source also records traditional use for wounds and bleeding. Those reports do not establish that such treatments are safe or effective.