1. (

• caltrop ,
• devil's_weed ,
• Tribulus_terestris

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

2. (

• water_chestnut ,
• water_chestnut_plant ,
• caltrop ,

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

3. (

• star-thistle ,
• caltrop ,
• Centauria_calcitrapa

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