Henbane (Hyoscyamus niger) is a poisonous plant of the nightshade family. CD had begun a series of experiments in the autumn of 1860 in an attempt to determine the effects of various poisons on the insectivorous plant Drosera rotundifolia (see Correspondence vol. 8). He discussed the results of the trials with henbane in Insectivorous plants, pp. 84, 206.