Guaiacum
 Guaiacum (/ˈɡwaɪ.ə.kəm/) sometimes spelled Guajacum is a genus of flowering plants in the caltrop family Zygophyllaceae. It contains five species of slow-growing shrubs and trees reaching a height of approximately 20 m (66 ft) but are usually less than half of that. All are native to subtropical and tropical regions of the Americas and are commonly known as lignum-vitae guayacán (Spanish) or gaïac (French).