Experimental evidence that the active principle of the poisonous plant Thesium lineatum L.f. (Santalaceae) is a bufadienolide.

The toxicity of Thesium lineatum is confirmed in sheep. A toxic crystalline bufadienolide, with the suggested trivial name thesiuside, has been isolated from it. This is the first cardiac glycoside to be isolated from a member of the Santalaceae. The toxin appears to have no cumulative effect and the symptoms of intoxication and pathology in sheep are similar to that expected from acute cardiac glycoside intoxication.