Parental species

 

The parental species used in this study are the Jacobaea vulgaris (Common ragwort) and Jacobaea aquatica (Marsh ragwort), formerly known as Senecio jacobaea and Senecio aquaticus.

 

Common ragwortJacobaea vulgaris, a parent

 

Jacobaea vulgaris is a monocarpic perennial plant that flowers from June until October.  Two subspecies are recognized J. vulgaris vulgaris and J. vulagris dunensis.  Subspecies are discerned by the absence of an outer row of hairless nutlets and presence of rayed flowers in J. vulgaris vulgaris. In the ragwort cross the subspecies J. vulgaris dunensis was used. This subspecies mainly occurs in the dunes in The Netherlands in regularly appearing and disappearing populations.  It occurs on sandy, dry soils which are mostly calcareous. From ragwort many specialist and generalist herbivores are known. It is reported to be attacked by over 60 herbivores in Great Britain. In Meijendel the most common specialist herbivores are  Tyria jacobaeae, Longitarsus jacobaeae, Aphis jacobaeae, Botanophila seneciella. Examples of generalist herbivores are the rabbit and Arctia caja.

 

 

 

 

Jacobaea aquatica, a parentMarsh ragwort

 

In Europe also two subspecies are recognized: Jacobaea aquatica subs aquatica and Jacobaea aquatica subs barbaraeifolius. In the cross the subspecies aquaticus was used. J. aquatica is less common than J. vulgaris and it grows on sunny sides that are waterlogged in the winter  and often dried out in the summer. Soils range from sand, clay to peat with a high organic content and low pH.  Relatively few herbivores species are reported to be feeding on marsh ragwort.  One specialist herbivore is reported to feed on marsh ragwort, is the plume moth Platyptilia isodactylis. The plume moth is also reported to occur on common ragwort.