Hyoscyamus
In general, Hyoscyamus spp. are known as Henbane and are very toxic. These contain potent narcotic and hyponotic alkaloids which are also valuable sources of medical drugs.
Erect, annual to perennial, hairy or glabrous herb. Leaves sinuate to pinnatipartite or rarely entire. Inflorescence a bracteate scorpioid cyme. Flowers somwhat zygomorphic. Calyx tubular-campanulate or urceolate, 5-dentate, accrescent in fruit, ribbed. Corolla funnel-shaped, lobes broad, imbricate, oblique. Stamens 5, inserted about or below middle of the corolla tube, usually exserted; filaments filiform, slightly dilate at the base; anthers ovate or oblong. Ovary 2-celled; style filiform; stigma capitate. Capsule enclosed in the enlarged clayx, 2-valved, dehiscence circumcissile. Seeds tubercled or pitted, reniform to orbicular.
About 20 species distributed in Mediterranean region, SW & C. Asia. Of these 5 species have been reported from Saudi Arabia.