Juncus acutus

Juncus acutus, the spiny rush, sharp rush or sharp-pointed rush, is a flowering plant in the monocot family Juncaceae.
It grows in salt marshes and on dunes and is reliable for reducing erosion rates.
In some countries like Australia it is considered to be an invasive weed and the spines harmful to young children.
Description.
"Juncus acutus" is a brown and green 
"tussocky" 
perennial that can be to 
tall in all kinds of soils, 
in areas which go from extremes in flood and dry like dunes
or that just stay wet like lowland grassland and grassy woodland, riparian vegetation, freshwater wetland, and saline and subsaline wetlands.
Distribution.
Found principally in low-lying damp, low fertility areas like sandy sea shores and dune slacks and coastal flats, occasionally in salt marshes and disturbed saline areas, mine dumps, lowland grassland and grassy woodland, riparian vegetation, freshwater wetland, and saline and subsaline wetlands
Chemistry.
The dimeric phenanthrenoid 8,8'-bidehydrojuncusol and the monomeric juncusol and dehydrojuncusol can be isolated from "J. acutus".