Natural Areas as well as our home gardens and roadsides are homes to a number of plants that are exotic invasive species. These are species that evolved elsewhere on the planet and are generalists, meaning they can live in a wide range of climates and habitats. There are about 150 that are such generalists that they can take over almost any habitat where they become established.
The dune is actually a very harsh environment so we have few exotic species. The ones that do live there tend to be annuals or short-lived perennials; they grow and bloom in the spring when there is little competition from indigenous plants. The fact that there are only a few invasive species and only seasonal does not diminish the fact that they take over the niche of indigenous species and confuse the native habitat.
We hand pull these plants rather than use herbicides, because herbicides do not distinguish between species. The ones that we pull in May and June are:
Bromus tectorum (Cheatgrass) It is an annual. This grass is called Cheatgrass because it can bloom twice in one season. It doesn’t do that on the dune because the environment is so harsh. It is ubiquitous and when you start to see it, it is suddenly everywhere in May and June. We rarely get ahead of this because it blooms and forms seeds in May, when our volunteer pool is smaller.
Medicago lupulina (Black medick) It is a relative of alfalfa. It has interestingly shaped seeds that are black. If we left it, there would be a mat of black medick and nothing else. Each plant can have as many as 1000 seeds. The flooding of the area seems to have washed the seeds all over and it is quite lush and has spread. This is what we have been focusing on the most.
Elymus repens (Quack grass) It is a cool season grass meaning it grows, flowers and seeds in the spring. We have it at the dune and it also grows in the lawn of Loyola Beach Park. It can live in most environments.