Source : WordNet®

helmet orchid
     n 1: any of numerous orchids of the genus Pterostylis having
          leaves in a basal rosette and green flowers often
          striped purple or brown or red with the dorsal sepal
          incurved to form a hood [syn: {greenhood}]
     2: any of several orchids of the genus Coryanthes having
        racemes of a few musky-scented waxy flowers with a
        helmet-shaped lip process [syn: {helmetflower}]