Alisma triviale aka Northern Water Plantain

Alisma triviale is called northern water plantain. This wetland plant lives for more than one year. It belongs to Alismataceae, the water-plantain family. Its native range starts in subarctic North America. It extends south to northern Baja California. It grows by ponds, streams, marshes, and wet ditches. Its roots grip mud or soil in shallow water. Leaves and flower stems rise above the water.

Garden plants grow about 2–3 feet [0.61–0.91 metres] tall. They spread about 2 feet [0.61 metres] wide. Rhizomes, or underground stems, support a ring of leaves at ground level. These gray-green leaves have long stalks. The blades range from broad ovals to lance shapes. They grow about 0.5–0.67 feet [0.15–0.20 metres] long. Plants in mud hold their leaves upright. Plants in water may have narrow, loose leaves. Tall flower stems rise from the leaf ring's center. They bear open, branched flower sprays called panicles. Small white flowers grow in rings along these sprays. The plant blooms from July through August. Small flies and bees visit the flowers. Some flowers also pollinate themselves.

Grow this plant in full sun and wet ground. Full sun gives the best bloom. Bogs and muddy pond or stream edges suit it. It also grows in water 0.17–0.5 feet [0.05–0.15 metres] deep. Pots can hold its corm-like bases in water gardens. Missouri Botanical Garden lists USDA hardiness zones 5–10. Plants For A Future gives a rough range of 3–8. Both sources say wetland sites suit this plant.

Northern water plantain suits water gardens and rain gardens. It also suits marshy ground. Tall flower sprays stand above its broad leaves. It gives water wildlife cover and places to feed. These include amphibians, water insects, and some waterfowl. Missouri Botanical Garden reports no serious pest or disease problems. Care is simple, but watch its spread by seed. It can sow lots of its own seeds. It may spread with force where sites suit it. To grow more, sow seed in wet mud. You can also divide plants in spring.

Plants For A Future names cooked rhizomes as the main edible part. Their starch gives them a potato-like taste and feel. Raw rhizomes are acrid and may cause irritation or mild poisoning. You must cook them well before you eat them. The source also notes roasting, drying, and grinding them into flour. Do not gather food from polluted water. The tiny seeds have little use as food. The same source lists no known medicinal uses.