He is best known for his popular book Magische Gifte: Rausch- und Betäubungsmittel der Neuen Welt ("Magic Poisons: Inebriating and Narcotic Substances of the New World"), first published in 1936.
This book recorded a number of second-hand observations on New World psychoactive drugs, paraphrased from notes he took of conversations with his cousin, the eminent Mexican ethnobotanist Dr. Blas Pablo Reko, including the first published refutation of Dr. William Edwin Safford's uncharacteristically untenable assertion that teonanácatl was not a mushroom, but a cactus.
for which he claimed psychoactivity,[1] Ololiúqui (Turbina corymbosa), peyotl (Lophophora williamsii), marihuana (Cannabis sativa), toloachi (Datura stramonium var.
tatula), ayahuasca, colorines (Erythrina and Sophora species), coztic-zapote (Pouteria campechiana), xomil-xihuite (Gelsemium sempervirens), camotillo (Dioscorea composita), and cohombrillo (Ecballium elaterium).
The second edition also contained chicalote (supposedly obtained from a cross between Argemone mexicana and Papaver somniferum), minapatli (Sebastiania pavoniana, Mexican jumping bean), and herbas locas (Dioon edule, Astragalus amphyoxys, and Oxytropis lambertii).