Root exudates, knapweed

C) Inhibitory compounds can be identified in knapweed and these are probably released into the soil environment. However, sesquiterpene lactones were not detected in root exudates, where the major components were long-chain carboxylic acids. 

Flavonoids are important secondary metabolites involved in pigmentation of flowers, disease resistance, and so on. Among the flavonoids, kaempferol (67), quercetin (68), and naringenin (69) are most often cited as allelochemicals. (zh)-Catechin was identified in the root exudates from spotted knapweed Centaurea maculosa) as the compound responsible for its invasive behavior.45 The plant uses (-)-catechin (70) as an allelochemical facilitating its invasion and (+)-catechin (71) as a defense compound against pathogens. 

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