WordNet (r) 3.0 (2006):

tower cress
    n 1: or genus Arabis: erect cress widely distributed throughout
         Europe [syn: tower mustard, tower cress, Turritis
         glabra, Arabis glabra]
    2: European cress having stiff erect stems; sometimes placed in
       genus Turritis [syn: tower cress, tower mustard, Arabis
       turrita]