Yellow tulp (Moraea pallida Bak.), collected predominantly during the flowering stage from a number of sites in South Africa, showed large variation in digoxin equivalent values, indicating variability in yellow tulp toxicity. Very low values were recorded for tulp collected from certain sites in the Northern Cape.
Snyman, L. D., Schultz, R. A., & Van den Berg, H. (2012). Variability of yellow tulp (Moraea pallida Bak.) toxicity. Journal of the South African Veterinary Association, 82(2). https://doi.org/10.4102/jsava.v82i2.48