Deep-rooted Marram creeps through sand
Marram is a wild plant that everyone must know. It is the coarse, grey-green, prickly grass that dominates most sand dunes around the entire coast of Ireland. In fact, it is almost exclusively confined to coastal sandhills and sandy shores where it binds the otherwise mobile substrate.
Garden lawn grasses have flat, blade-like leaves. Marram also has blade-like leaves but instead of being flat they are rolled into a tight tube much as one can do by rolling a flat sheet of paper into a narrow cylinder.
Plants breathe and sweat through the lower surfaces of their leaves. Marram has rolled leaves to conserve water considering the harsh, dry, sandy, well-drained habitat it lives in. The lower surface of the leaf is on the inside of the roll. The upper, now outer, surface is protected by a thick coat of a waxy material to further prevent water loss due to drying, on-shore winds.
One of the consequences of rolling and the wavy coating is that the tips of the blades are rigid, very sharp, spiky and prickly, an unwelcome circumstance for summer beach-goers with bare legs walking through waist-high clumps of Marram on the dunes. The waxy skin is so tough that running a hand along the blades can result in a cut.
Marram is a perennial and native wild plant. The word ‘Marram’ is believed to be derived from Old Norse and is part of our Viking legacy. While ‘ Marram’ is the preferred name for the species, in many parts of Ireland the plant is known by the local names such as ‘ bennet’ or ‘ bent’. In the past, the tough grass has been used for thatching by coastal communities.
At present, the grass has leaf blades only. In July and August its flowers appear. Like all grasses its flowers are not showy or colourful. As illustrated above, they are thick, spike-like, straw-coloured flowerheads some 15cm long tapered at both ends. Each flowerhead is a crowded mass of one-flowered spikelets with long, silky hairs making each spike soft to the touch in contrast to the rough leaves.
Rhizomes are underground stems that creep horizontally. Marram is deeply rooted and has rhizomes that are several metres long. They creep unimpeded through the sand sending up dozens of new shoots. A single clump can send out rhizomes in all directions reproducing the plant vegetatively and stabilising the mobile sand that they creep into.