Source : Webster's Revised Unabridged Dictionary (1913)

Sea holly \Sea" hol"ly\ (Bot.)
   An evergeen seashore plant ({Eryngium maritimum}). See
   {Eryngium}.

Eryngium \E*ryn"gi*um\ ([-e]*r[i^]n"j[i^]*[u^]m), n. [NL., fr.
   Gr. 'hry`ggion, dim. of 'h`ryggos eryngo; cf. L. eryngion,
   erynge.] (Bot.)
   A genus of umbelliferous plants somewhat like thistles in
   appearance. {Eryngium maritimum}, or sea holly, has been
   highly esteemed as an aphrodisiac, the roots being formerly
   candied.

Source : WordNet®

Eryngium maritimum
     n : European evergreen eryngo with twisted spiny leaves
         naturalized on United States east coast; roots formerly
         used as an aphrodisiac [syn: {sea holly}, {sea holm}, {sea
         eryngium}]