The Collaborative International Dictionary of English v.0.48:

Sinapis \Si*na"pis\, n. [L.] (Bot.)
   A disused generic name for mustard; -- now called Brassica.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Brassica \Bras"si*ca\, prop. n. [L., cabbage.] (Bot.)
   A genus of plants embracing several species and varieties
   differing much in appearance and qualities: such as the
   common cabbage (Brassica oleracea), broccoli, cauliflowers,
   etc.; the wild turnip (Brassica campestris); the common
   turnip (Brassica rapa); the rape or coleseed (Brassica
   napus), etc.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Brassica
    n 1: mustards: cabbages; cauliflowers; turnips; etc. [syn:
         Brassica, genus Brassica]