Source : Webster's Revised Unabridged Dictionary (1913)

Silverweed \Sil"ver*weed`\, n. (Bot.)
   A perennial rosaceous herb ({Potentilla Anserina}) having the
   leaves silvery white beneath.

Source : WordNet®

silverweed
     n 1: any of various twining shrubs of the genus Argyreia having
          silvery leaves and showy purple flowers
     2: low-growing perennial having leaves silvery beneath;
        northern United States; Europe; Asia [syn: {goose-tansy},
        {goose grass}, {Potentilla anserina}]