Caspian grass (Calamagrostis brachytricha 'Caspian') is a decorative, clump-forming perennial grass with lush green blades and fluffy, pale pink plumes that turn white in late summer. It grows in full sun or light shade, requires moist soil, and is valued for its heat tolerance and vertical, four-foot-tall structure. Caspian generally grows to a mature height of 3 to 4 feet and is around 1.5 to 2 feet broad.