The process of simultaneous fertilization of two spermatozoa, one with the ovum and the other with the secondary nucleus, is called double fertilization. Dicotyledons occur in herbaceous plants. In 1990, scientist Williams Friendman discovered bi-toxicity in the gymnosperm Ephedra. In 1898 scientist Navasin observed double fertilization in Lilium martagon and Fritellaria tenella plants. Double fertilization occurs in paddy, wheat, bhutra, redi etc.