It is a herbaceous perennial plant growing to 1 m tall, with hairless stems and leaves. The leaves are rounded, 5-10 cm diameter, palmately divided into five to seven deeply lobed segments. The flowers are dark purple to bluish-purple, narrow oblong helmet-shaped, 1-2 cm tall.
Nine subspecies are accepted by the Flora Europaea:
Plants native to Asia and North America formerly listed as A. napellus are now regarded as separate species.
Plants are grown in gardens in temperate zones for their spike-like inflorescences that are showy in early-mid summer and their attractive foliage. There are white and rose colored forms in cultivation too.
Like other species in the genus, A. napellus contains several poisonous compounds, including enough cardiac poison that it was used on spears and arrows for hunting and battle in ancient times. A. napellus has a long history of use as a poison, with cases going back thousands of years. During the ancient Roman period of European history the plant was often used to eliminate criminals and enemies, and by the end of the period it was banned and any one growing A. napellus could have been legally sentenced to death. Aconites have been used more recently in murder plots; they contain the Chemical alkaloids aconitine, mesaconitine, hypaconitine and jesaconitine, which are highly toxic.
Aconite produced from the roots of a number of different species of Aconitum is used ethnomedically in Traditional Chinese Medicine (TCM), to treat "coldness", general debility, and "Yang deficiency." Such use has been shown in some cases to negatively affect the cardiovascular and central nervous systems including documented instances of poisoning and death.