Triglochin maritima aka Sea Arrow Grass

Triglochin maritima is known as sea arrowgrass. It is a perennial, so it lives for more than two years. It belongs to the Juncaginaceae family. It grows from rhizomes, which are stems below ground. Its native range spans the Northern Hemisphere's temperate parts. That range also takes in southern South America. It is native to Britain, Ireland, and the American Midwest. Wild plants grow in salt marshes and grassland near the sea.

The plant grows upright to about 2 feet [0.6 metres]. Its leaf stems have white bases below their green parts. The flowers are white or green. Chicago Botanic Garden gives May through August as bloom time. Plants For A Future gives July through September. These dates suggest that growing conditions can affect bloom time. Wind carries pollen from flower to flower. Each flower has both male and female organs. Seeds ripen from August to October.

Grow sea arrowgrass in full sun, not shade. It needs moist to wet ground. It can also grow in shallow water. A bog garden or pond edge suits these needs. It grows in sand, loam, and clay. This leaves few limits on soil texture. It accepts neutral to alkaline soil, even very alkaline ground. It can cope with salty soil, but may not need salt. Plants For A Future says it can stand strong winds. Yet that source says it cannot stand maritime exposure. Chicago Botanic Garden lists USDA hardiness zones 3–8. It also lists the plant for beds and borders.

Take care with food uses, as parts contain toxins. Plants For A Future records raw or cooked white leaf-stem bases as food. It notes a mild, sweet taste and a late spring harvest. Cooking can cause a bad smell. The source warns not to eat the green parts. It also warns not to eat the bases of flowering stems. It records parching seeds and grinding them for food. Roasted seeds have served in place of coffee. These uses do not make the whole plant safe.

Green leaves can contain cyanogenic glycosides. The risk is greater during and after drought. Cattle and sheep face a marked risk if they eat it. Cornell lists the whole plant as poisonous, including leaves and flowers. It names the toxins as taxiphillin and triglochinin. The plant's ash contains potassium and has served in soap making. Plants For A Future records no known medicinal use. It flags a risk of weed growth but gives no rate of spread. You can divide plants in spring to grow more.