Small, Journal of the New York Botanical Garden 20(230): 29, 1919
Opuntia ammophila was once considered a variety of O. humifusa; however, it is a distinct species. The species was more commonly found 100 years ago and sometimes grew to the height of humans with thick woody trunks. Today, plants are seldom 3-ft tall. Unlike other opuntias of Florida, it has gray-green cladodes. The flowers are light yellow and the stigma is cream colored. Tepals are distinctly recurved. It also has numerous long, thin spines that may be deflexed. Plants occur in lower Florida, and the type specimen was from Ft. Pierce in sand dunes. Britton and Rose reported that O. ammophila typically has a single trunk and can appear tree-like; even small plants may be upright from a single stem. Some authors propose that O. ammophila is a form of O. austrina. See the original citation.