Coumestrol: A daidzein derivative occurring naturally in forage crops which has some estrogenic activity.Phytoestrogens: PLANT EXTRACTS and compounds, primarily ISOFLAVONES, that mimic or modulate endogenous estrogens, usually by binding to ESTROGEN RECEPTORS.Estrogens, Non-Steroidal: Non-steroidal compounds with estrogenic activity.Lignans: A class of dibenzylbutane derivatives which occurs in higher plants and in fluids (bile, serum, urine, etc.) in man and other animals. These compounds, which have a potential anti-cancer role, can be synthesized in vitro by human fecal flora. (From Singleton & Sainsbury, Dictionary of Microbiology and Molecular Biology, 2d ed)Isoflavones: 3-Phenylchromones. Isomeric form of FLAVONOIDS in which the benzene group is attached to the 3 position of the benzopyran ring instead of the 2 position.Plant Root Nodulation: The formation of a nitrogen-fixing cell mass on PLANT ROOTS following symbiotic infection by nitrogen-fixing bacteria such as RHIZOBIUM or FRANKIA.