Our area was under a drought watch for most of the spring, and one impact of this on Minnie’s Island was the delay of the typical spring growth spurt for herbaceous plants, such as goldenrods and sunflowers, until after Memorial Day. This has resulted in a banner year for grasses, which are more drought tolerant, which benefited from the extra sunlight for most of the spring. In this article, we’ll take a look at the most common grasses found at Minnie’s Island and along the river. All of these native grasses can be used in our home gardens and can be found at local nurseries.
Northern sea oats (Chasmanthium latifolium) is known for its attractive oat-shaped seed heads. It is a cool season grass that grows through the winter and spring, turns brown during the summer, and provides visual interest with the seeds remaining through the winter. I have a stand of this forming a low screen around our patio. It also looks great as a dried arrangement. It can be aggressive in home gardens, however.
It is easy to identify bottlebrush grass (Elymus hystrix) when it is in bloom, as the bristly seed heads resemble a bottle brush. It is another cool season grass that starts growing in late winter, blooms in June, and then retains brown leaves and seeds through early winter. I have a small stand of this attractive grass in the front yard.
Big bluestem (Andropogon gerardi) is the iconic species of midwestern tall grass prairies. In the Potomac Gorge, including Minnie’s Island, it is found on rock outcrops along the river. It is a warm season grass that doesn’t start actively growing until late spring. The seed heads of this grass are stunning while in bloom, with bright purples and yellows. Many cultivars of this grass are available at local nurseries. I have several of these growing in large containers.
Deertongue grass (Dichanthelium clandestinum) is a warm season grass named for its broad, deer tongue-shaped leaves. It is common on Minnie’s Island, forming large clumps that can get up to four feet tall. Of the grasses listed, it is probably the least commonly used in home gardens, although it is hardy and attractive.
Broomsedge bluestem (Andropogon virginicus) is a warm season grass (not a sedge) that is spreading in the portion of Minnie’s Island that we manage as a meadow. It retains a golden-orange color through the winter, and is a common landscaping plant. The name comes from its use in the construction of simple brooms in the past.
Other grasses found on Minnie’s include switchgrass (Panicum viratum), purpletop tridens (Tridens flavus), Virginia wildrye (Elymus virginicus), plus several others that I have not been able to identify. There are also many attractive sedges on the island, but those are also difficult to identify.
At the time of writing, Minnie’s Island is still closed to the public due to contaminated sediment from DC Water’s sewage spill in January. We hope to re-open after sediment testing results return to baseline and Montgomery County Department of Health lifts their advisory to avoid the sediment and Community shoreline from Lock 11 down to Minnie’s Island. [Editor’s Note: Minnie’s Island has reopened!]
By Joe Saliunas, Maryland Master Naturalist, Board Chair of Minnie’s Island Community Conservancy
Contributing Writer