The rough greensnake averages 22 to 32 inches in length. It is very slender with a green back and a white, yellow or pale-green belly. The scales are keeled (ridged). After the snake dies, the body color changes to a dull blue. The mouth cavity is purple.
The rough greensnake may be found in the southern one-half of Illinois. It lives in vegetation around water, particularly forest edges. The rough greensnake is semiaquatic, entering water as well as living on land. It is excellent at climbing, often foraging and resting in shrubs and trees. This snake is active during the day. Mating occurs in spring. The female deposits from four to six eggs under a rock, in leaf litter, in a brush pile or in a rotten stump during June or July. Eggs hatch in August or September. This snake eats insects and spiders.