Birchbank has more early spring wildflowers than anywhere else I know of in Shelton. But it also has some serious issues with invasive species. Garlic Mustard, Japanese Knotweed, and Japanese Barberry are the worst problems. In the photo above you can see a native Trout Lily (left) and Red Trillium (right) being overrun by invasive Japanese Barberry.
Japanese Knotweed, a tall plant some people call Cane, is notoriously difficult to kill, and can survive repeated applications of Round-Up. Near the parking area, the knotweed is spreading into areas that were once solid mats of Dutchman's Breeches and Red Trillium. In the photo above you can see flowering Breeches along with old stalks from the Knotweed and fresh Knotweed sprouts.
The surviving Dutchman's Breeches also have to contend with illegal ATVs trampling the area.
The sprouts of Japanese Knotweed are edible, and though they look like asparagus they taste more like tart rhubarb. There are lots of recipes online. Garlic Mustard is also edible and in fact was brought to this country for cooking. Garlic Mustard pesto is very good.
Here's a Red Trillium competing with the Japanese Knotweed. At least it gets out early each spring before the Japanese Knotweed can overtake it. Here's a video about Japanese Knotweed.