It is now recognized as an energetic cardiac poison, comparable with strophanthus, destined to play an important part in therapeutics.
"The Medicinal Plants of the Philippines"
T. H. Pardo de Tavera
strophanthus, for instance, was very popular a quarter of a century ago, and it seems as though in many cases it not only replaced, but was more efficient than digitalis.
"Psychotherapy"
James J. Walsh