Agkistrodon piscivorus leucostoma is a stout snake with a thick, muscular body.

[11] Its broad, flat head is distinctly wider than its neck, and it has an elliptical (cat-like) pupil.

[12] The animal opens its mouth widely when startled, exposing its whitish-colored oral mucosa; this is the reason it is commonly referred to as the "cottonmouth".

[10] Found in the United States, from southern Alabama along coast of the Gulf of Mexico, including many offshore islands, to southeastern and central Texas and north to Oklahoma, Missouri, Illinois, Indiana, and southeastern Nebraska, and western Kentucky.

Schmidt (1953) proposed that this be amended to "10 miles northeast of Bolivar, Hardeman County, Tennessee".