The Collaborative International Dictionary of English v.0.48:

Morus \Mo"rus\, n. [L., mulberry tree. See Mulberry.] (Bot.)
   A genus of trees, some species of which produce edible fruit;
   the mulberry. See Mulberry.
   [1913 Webster]

   Note:

   Morus alba is the white mulberry, a native of India or
      China, the leaves of which are extensively used for
      feeding silkworms, for which it furnishes the chief food.


   Morus multicaulis, the many-stemmed or Chinese mulberry, is
      only a form of white mulberry, preferred on account of its
      more abundant leaves.

   Morus nigra, the black mulberry, produces a dark-colored
      fruit, of an agreeable flavor.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Morus nigra
    n 1: European mulberry having dark foliage and fruit [syn:
         black mulberry, Morus nigra]