PNW Landscape Plant Guide

brought to you by the plant geeks at Calendula Farm

American Dunegrass (Leymus mollis)

Ok, we’re going to dive deep into the weeds with this one. American Dunegrass is native to the Northwest coast, upper Midwest, New England, most of Canada, and far northern Asia. It plays a critical role in the ecological health of most shorelines, specifically in stabilizing and controlling erosion of sandy dunes and beaches from both wind and water. The importance of this plant cannot be understated. In the 1930s, some nincompoops thought that the stable ecology of seaside dunes that has existed for tens of thousands of years was not good enough, so they introduced European Beach Grass to ‘stabilize’ the shorelines. This grass immediately became invasive, altered the natural balance, and has now caused devastating erosion and instability along shorelines from California to British Columbia.

We hate lead with a bummer, but there you have it. The good news is that major efforts have been underway for a few decades to eradicate the destructive introduced weed, and put back the plant that belongs there. A wonderful example of American Dunegrass is along the shoreline adjacent to Ruston Way in Tacoma. It has been beautifully planted at Dune Peninsula Park and an even better example is on the beachfront trail between Mary Coss’ sculpture at Dickman Mill Park and the fishing pier to the west.

American Dunegrass grows as a collection of 2-3 foot tall distinctively blue-green, stiffly upright, 1/2 inch wide leaves. In early summer it shoots up bloom spikes that look a little like oversized wheat. In fact, for many decades it has been crossed with wheat to make more durable strains of the world’s primary food crop. The plant does its stabilization job with a densely spreading web of rhizomatous roots. It withstands little to no fresh water, can be submerged by waves or sand and still carry on, and the leaves are nearly unbreakable. Original coastal people used them for basketry. Despite its capacity for harsh conditions, it will happily grow in your garden, adding great texture and color.