Seasonal age-specific measurements of the sesquiterpene lactones and chromenes of Encelia farinosa

• Published in: Biochemical systematics and ecology 1983-01, Vol.11 (4), p.345-352
• Main Authors: Wisdom, C.S., Rodriguez, E.
• Format: Article
• Language: English
• Subjects: age-specific variation; Asteraceae; Biological and medical sciences; Chemical constitution; chromenes; Encelia farinosa; Fundamental and applied biological sciences. Psychology; Plant physiology and development; quantitative analysis; seasonal variation; sesquiterpene lactone
• ISSN: 0305-1978; 1873-2925
• DOI: 10.1016/0305-1978(83)90035-2

Age-specific concentrations of farinosin, a sesquiterpene lactone, and encecalin and euparin, both chromenes, were measured in two semi-desert populations of Encelia farinosa in California over a three month period. All three natural products differed significantly in concentration. The average concentration of encecalin is 10 times that of euparin and eight times that of farinosin. Farinosin concentrations did not differ between the two populations, but both euparin and encecalin were in higher amounts in the UC Riverside population than in the Home Gardens population. Seasonal changes in natural products differed at the 0.05 level for all populations and compounds except euparin in the UC Riverside population. Percent nitrogen content of dried leaves was similar in both populations, but differed between collection dates. Water content did not vary significantly with leaf age on one collection date. The significance of these results is discussed in the light of herbivore history.