arrowgrass

/ (ˈærəʊˌɡrɑːs) /

noun

either of two species, sea arrowgrass (Triglochin maritima) or marsh arrowgrass (T. palustris), of monocotyledonous perennials having long thin fleshy leaves and spikes of inconspicuous flowers

Word Origin for arrowgrass

C18: named from the shape of the fruits when open