The approximately 500,000 ponds--both artificial and natural--dotting Britain's heaths, highlands and aristocratic estates are home to an enormous diversity of native British pond plants. Many of these freshwater plants have an endangered status, according to the Wildlifeextra.com website. Others, however, are common sites in home garden ponds, providing months of color or form. They also attract Britain’s native creatures, including blue flea beetles, with shelter, food and nesting materials.
Yellow iris (Iris pseudacorus), often called yellow flag, is common across England, Ireland and much of Scotland. Growing in shallow water or mud along stream edges, this is a rapidly spreading plant, sometimes to the point of being invasive. A single rhizome, in fact, can produce up to 100 plants. Yellow iris also self-sows from seed. Growing it in submergible containers may be a solution for gardeners with small ponds, according to the Natural England website.
Between May and July, stems up to 4 feet long rise above its clumps of sword-shaped green leaves, lighting the water's edge with bright yellow blooms. Their sepals--protective outer petals--may have brown or purple markings. Happiest in full sun to part shade, perennial yellow iris may be evergreen green during warm winters.
A charming and common sight in ponds along the southern and southeastern English coasts, annual European frogbit (Hydrocharis morsus-ranae) floats on top of the water, supported by its spongy leaves. The roots of plants in small colonies also float freely, according to the Natural England.com website. Large numbers of plants, however, may attach to a pond’s bottom. A small plant, frogbit has green-veined, water lily-like leaves topped with yellow-centered, white blooms. The three-petaled, crinkled flowers appear from mid-to-late-summer. Underwater mud buries the plant’s buds like hibernating frogs during its winter dormancy.
Marsh marigold, or king’s cup (Caltha palustris), is a shallow-water or marginal soil pond plant growing across Britain. King's cup is the more descriptive name for its brilliant yellow, buttercup-like flowers. Up to 2 inches across, they appear on its branching stems as early as March and continue until June. Growing up to 18 inches high and wide from a base of round or heart-shaped, glossy green leaves, this tough little plant handles winter temperatures as low as minus 40 degrees F. Insects come to collect its pollen, and frogs and wildlife shelter in its foliage, according to the Natural England website. Cooking its young leaves and flowers makes them edible. Marsh marigold flowers best in full sun.