Shrub identification request
This appears to be a variety of Crepemyrtle (Lagerstroemia), though when out-of-bloom, we cannot tell which. (Even then, there's some overlap in varieties.) There are many varieties of dark-leaved crepemyrtles on the market nowadays that have been introduced in recent years. The main difference between them is flower color (red, white, several shades of pink, and shades of reddish-purple), though a few may have different mature sizes as well. They were introduced as having more multi-season interest due to the strikingly-colored foliage; some are purported to also have good resistance to powdery mildew and other leaf ailments. If the park staff don't know the variety planted, you could take a photo (or a flower sample, as photographs can distort the true color of things, if the nuance of the color matters) and bring it to a local nursery/garden center to see if it matches up with varieties they stock.
Some of the names we've seen of series of dark-leaved crepemyrtle include "Black Diamond," "Delta," and most recently, "Thunderstruck." Their marketing names may differ from their true cultivar names, which are often an unpronounceable mix of letters and numbers; marketed names are often trademarked, but other sellers may be allowed to sell the plants under different trade names. In both cases, the actual cultivar name, written in single quotes, will be the same. This way you can be sure you're looking at the same plant, even if it's coming from different sources. Plant tags usually include the cultivar name even if they also print the trademarked name.