Hognut or pignut can mean any of a number of unrelated plants:

• Bunium bulbocastanum (black cumin) or Conopodium majus (kippernut) of the Apiaceae
• rushpeas, particularly Hoffmannseggia glauca (Indian rushpea) and Hoffmannseggia densiflora, of the Fabaceae
• Carya glabra (pignut hickory) of the Juglandaceae
• Hyptis suaveolens (chan), also known as Mesosphaerum suaveolens, of the Lamiaceae