The Collaborative International Dictionary of English v.0.48:

Roseroot \Rose"root`\, n. (Bot.)
   A fleshy-leaved herb (Rhodiola rosea); rosewort; -- so
   called because the roots have the odor of roses.
   [1913 Webster]

WordNet (r) 3.0 (2006):

rose-root
    n 1: Eurasian mountain plant with fleshy pink-tipped leaves and
         a cluster of yellow flowers [syn: rose-root, midsummer-
         men, Sedum rosea]