Sagittaria latifolia aka Broadleaf Arrowhead

Sagittaria latifolia is an aquatic perennial in the Alismataceae family. Common names include broad-leaved arrowhead, duck potato, and wapato. Its native range spans Canada, much of the United States, and Cuba. It also reaches Central America and western South America. It grows in ponds, ditches, lakes, marshes, and swamps. People grow it for food and as a pond plant.

Plants form upright clumps and spread through stolons below ground. These stems produce starchy tubers that store food. Garden sources give heights of about 2–3.3 feet [0.6–1 metre]. Chicago Botanic Garden reports plants reaching 4 feet [1.2 metres]. Other accounts describe shorter clumps near 1.5 feet [0.45 metres]. Reported spreads range from 0.3–2.7 feet [0.1–0.8 metres]. The green leaves lack hairs and fall at season's end. Their shape ranges from narrow and lance-shaped to broad arrows. RHS gives leaf lengths near 1 foot [0.3 metres]. NC State reports much longer leaves, reaching 2.7 feet [0.8 metres].

White flowers rise in racemes above the leaves. Each flower has three petals around a yellow centre. Flowers grow in groups of three along the stalk. RHS reports blooms about 0.13 feet [0.04 metres] across. Flowering runs from June to October, though timing varies by place. Brown fruits appear from August through November. Insects pollinate the flowers, and bees visit them. The plant also draws birds to wet gardens. At least fifteen duck species eat its underground tubers. Snapping turtles eat them too.

Grow it in sun, though it also accepts part shade. It needs moist or wet ground and suits pond edges. It grows in clay, loam, or sand across varied pH levels. Shallow water may stand still or flow slowly. Suitable water depths reach about 0.4 feet [0.12 metres]. Published USDA ranges differ: Chicago lists 5–10, NC State 3–11. RHS rates it H6 for UK conditions. Water lily aphids may attack, but diseases cause few problems.

This plant can spread into large colonies and become weedy. England and Wales prohibit planting or releasing it into the wild. Gardeners there must keep it contained. Its tubers have long served as food for Indigenous peoples. People eat them raw or cooked, though raw skins taste bitter. Cooked tubers can be peeled, dried, and ground into flour. Sources report no known hazards and describe minor traditional medicinal uses.