Stinging Nettle Trail is a 4.8 mile moderately trafficked out and back trail located near Ballwin, MO that features a river. The trail is rated as moderate offers a number of activity options.
The Stinging NettleTrail offers an easy, scenic walk along the bottomland of the Meramec River. If you wish to make a loop out of it instead of an out-and-back, I would suggest taking the Al Foster Trail from the Herman Park Trailhead, then come back along the river on the Stinging Nettle. It is a very easy, wide single-track walk most of the way, with a total elevation gain of only about 130 feet over the 5 mile route.
Lots of solitude and nice foliage, At the eastern end where the trail turns around, there are signs that you are entering private property. However, it's Castlewood Park. I did not go further, but it appears that it connects with Castlewood's River Scene Trail.
For some reason I prefer the section of the Al Foster that goes west from the Sherman trailhead to Glencoe, as it's a little more scenic in my book, but it depends on what you like.