Datura innoxia is a tuberous-rooted, subshrub that typically reaches a height of 0.6 to 1.5 metres. Its stems and leaves are covered with short and soft grayish hairs, giving the whole plant a grayish appearance. It has elliptic smooth-edged leaves with pinnate venation. All parts of the plant emit a foul odor similar to rancid peanut butter when crushed or bruised, although most people find the fragrance of the flowers to be quite pleasant when they bloom at night.
The flowers are white, trumpet-shaped, 12–19 cm (4.5–7.5 in) long. They first grow upright, and later incline downward. It flowers from early summer until late fall.
The fruit is an egg-shaped spiny capsule, about 5 cm in diameter. Like those of other species belonging to section Dutra of the genus Datura, it splits open irregularly when ripe to disperse its seeds. Another means of dispersal may also occur, in which the spiny fruit becomes entangled in the fur of animals, who then carry the fruit far from the mother plant. The seeds are long-lived, having the ability to lie dormant in the soil for many years. The seeds and indeed the whole plant, have strongly delerient properties and a high potential for overdose, the slow appearance of the effects leading to the erroneous belief that the dose taken has been ineffective.