As native grasses such as little bluestem (Schizachyrium scoparium and cvs., Zones 3–9) and prairie dropseed (Sporobolus heterolepis and cvs., Zones 3–9) increasingly gain traction in gardens, exotics such as miscanthus (Miscanthus sinensis and cvs., Zones 4–9) are losing favor because of their invasive tendencies. But not all exotic grasses are troublesome and need to be avoided. Feather reed grass (Calamagrostis × acutiflora and cvs., Zones 5–9) is a natural hybrid of C. arundinacea and C. epigejos, which are both nonnatives and prolific self-sowers, but the hybrid rarely sets fertile seed—a major plus for an exotic grass, right? So why are other reed grasses—‘Karl Foerster’ aside—so underused? To answer that question is to understand the phenomenon of ‘Karl Foerster’ feather reed grass (C. × acutiflora ‘Karl Foerster’).