pigweed

noun6

1. •
   Any of various weedy plants sometimes used as pig fodder

   • He still carried the basket with the shags and pig-weed. — 1941
2. •
   Amaranthus species.
3. •
   Chenopodium album, white goosefoot.
4. •
   Portulaca bicolor, of Australia.
5. •
   Polygonum aviculare (common knotgrass).
6. •
   (dialect) Heracleum sphondylium.