Nigella is a genus of 18 species of annual plants in the family Ranunculaceae, native to southern Europe, north Africa, south and southwest Asia.
 Common names applied to members of this genus are nigella, devil-in-a-bush or love-in-a-mist.
Leucanthemella is a genus of flowering plants in chamomile tribe within the sunflower family.
Thymoquinone is a phytochemical compound found in the plant "Nigella sativa".
 It is also found in select cultivated "Monarda fistulosa" plants grown and steam distilled in the USA producing an essential oil.

Question: Are both Nigella and Leucanthemella both plants?
Answer: yes