[Wikipedia] Habitat, Range, Life Cycle, Toxicity: Triglochin maritima is a species of flowering plant in the arrowgrass family Juncaginaceae. It is found in brackish marshes, freshwater marshes, wet sandy beaches, fens, damp grassland and bogs. It has a circumboreal distribution, occurring throughout the northern Northern Hemisphere. In the British Isles it is common on the coast, but very rare inland.
It can be an annual or perennial.[6]
This plant is believed to be toxic, as it can produce cyanide. However, this is usually when the plant is distressed in drought conditions or due to over harvesting, usually by grazing animals. There is a common belief that this species has been known to cause losses in cattle, with green leaves being more toxic than dried material, yet sheep and deer graze on the plant, especially in rural seaside areas. It could be that belief in the plants' toxicity is apocryphal and based on anecdotal evidence.[8][2] (link added by Mary Ann Machi)