Wildflowers and blooming trees, bushes, and vines.

Sources:

Blue Ridge Parhway Bloom Calendar: https://www.nps.gov/blri/learn/nature/upload/Blue-Ridge-Parkway-Bloom-Calendar.pdf

Blue Ridge Parkway Wildflower Bloom Schedule http://www.virtualblueridge.com/nature-guide/wildflowers/

Bloom Schedule http://www.blueridgeparkway.org/v.php?pg=77