Senecio triangularis

Senecionine Pyrrolizidine Senecio triangularis Pedicularis semibarbata... 

Senecio taiwanesis hayata (rosmarinecine), 240 Senecio triangularis (rosmarinecine),... 

The stems and leaves of Castilleja rhexifolia (Scrophula-riaceae) contain senecionine (5) and its A -oxide (obtained from Senecio triangularis) as their main alkaloids. The major alkaloid of the blossoms and seeds is rhexifoline, an iridoid-monoterpene-derived alkaloid, which is found in many Castilleja species. These plants serve as a host for the plume moth, Platyptilia pica. The larvae primarily eat the green seeds. Both the larvae and the adults of this insect contain rhexifoline (Roby and Stermitz, 1984). Plants of C. hispida contain quinolizidine alkaloids, and occasional plants of C. sulphurea contain quinolizidine alkaloids, whereas those of C. occidentalis do not contain alkaloids other than rhexifoline. The iridoid monoterpene content of all these alkaloids is similar. The larvae were found to excrete the monoterpene iridoids (Stermitz et al., 1986). 

Plants from five species of Pedicularis (Scrophularia-ceae) take up alkaloids from their host plants. Those of Pedicularis groenlandica and P. bracteosa take up senecionine (5) from the host Senecio triangularis. Those of Pedicularis crenulata contain anagyrine (Fig. 30.1) (a quinolizidine alkaloid) from the host Thermopsis divaricarpa. Plants of Pedicularis racemosa contain quinolizidine alkaloids from a Lupinus argenteus hybrid (Schneider and Stermitz, 1990). 

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