The Collaborative International Dictionary of English v.0.48:

Sweetbrier \Sweet"bri`er\, n. (Bot.)
   A kind of rose (Rosa rubiginosa) with minutely glandular
   and fragrant foliage. The small-flowered sweetbrier is Rosa
   micrantha.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sweetbrier
    n 1: Eurasian rose with prickly stems and fragrant leaves and
         bright pink flowers followed by scarlet hips [syn:
         sweetbrier, sweetbriar, brier, briar, eglantine,
         Rosa eglanteria]