Atropa belladonna: A plant species of the genus ATROPA, family SOLANACEAE that contains ATROPINE; SCOPOLAMINE; BELLADONNA ALKALOIDS and other SOLANACEOUS ALKALOIDS. Some species in this genus are called deadly nightshade which is also a common name for SOLANUM.Atropa: A plant genus of the family SOLANACEAE which contain SOLANACEOUS ALKALOIDS including ATROPINE which is named after this genus.Belladonna Alkaloids: Alkaloids obtained from various plants, especially the deadly nightshade (Atropa belladonna), variety acuminata; atropine, hyoscyamine and scopolamine are classical, specific antimuscarinic agents with many pharmacologic actions; used mainly as antispasmodics.Hyoscyamus: A plant genus of the family SOLANACEAE which contains TROPANES.Solanaceous Alkaloids: Alkaloids, mainly tropanes, elaborated by plants of the family Solanaceae, including Atropa, Hyoscyamus, Mandragora, Nicotiana, Solanum, etc. Some act as cholinergic antagonists; most are very toxic; many are used medicinally.Materia Medica: Materials or substances used in the composition of traditional medical remedies. The use of this term in MeSH was formerly restricted to historical articles or those concerned with traditional medicine, but it can also refer to homeopathic remedies. Nosodes are specific types of homeopathic remedies prepared from causal agents or disease products.