caltrop

Noun

• Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America

• a plant of the genus Trapa bearing spiny four-pronged edible nutlike fruits

• tropical annual procumbent poisonous subshrub having fruit that splits into five spiny nutlets; serious pasture weed

Related words

• Synonyms: 
  star-thistle , Centauria calcitrapa , water chestnut , water chestnut plant , devil's weed , Tribulus terestris