aka spider lily

Tradescantia virginiana
Commelinaceae

More than two dozen species of Tradescantia grow in the US; most are natives, a few are alien.  Of these, only this one and T. ohiensis can be found in the Maryland Piedmont.  The plants stand two to three feet tall, and like moist soils and some shade.  The flowers open in the morning and close by early afternoon (maybe later on overcast days).  Each flower lasts only one day, but the plant can produce flowers over a period of a month or more.

This is a nice plant for the garden, and there are many hybrids in the nursery trade. Remember, if you garden to benefit wildlife (bees and butterflies visit spiderwort), look for the species rather than cultivars, which are often not recognized by the wildlife you’re trying to attract.

Here are a few brief articles on the subject:
http://www.audubon.org/news/how-buy-native-plants
http://pollinatorgardens.org/
http://www.dcnr.state.pa.us/forestry/plants/nativeplants/