The Collaborative International Dictionary of English v.0.48:

Mayflower \May"flow`er\, n. (Bot.)
   In England, the hawthorn; in New England, the trailing
   arbutus (see Arbutus); also, the blossom of these plants.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Arbutus \Ar"bu*tus\, Arbute \Ar"bute\, n. [L. arbutus, akin to
   arbor tree.]
   The strawberry tree, a genus of evergreen shrubs, of the
   Heath family. It has a berry externally resembling the
   strawberry; the arbute tree.
   [1913 Webster]

   Trailing arbutus (Bot.), a creeping or trailing plant of
      the Heath family (Epig[ae]a repens), having white or
      usually rose-colored flowers with a delicate fragrance,
      growing in small axillary clusters, and appearing early in
      the spring; in New England known as mayflower; -- called
      also ground laurel. --Gray.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Mayflower
    n 1: the ship in which the Pilgrim Fathers sailed from England
         to Massachusetts in 1620
    2: low-growing evergreen shrub of eastern North America with
       leathery leaves and clusters of fragrant pink or white
       flowers [syn: trailing arbutus, mayflower, Epigaea
       repens]