Senecio jacobaea - part three

Apologies for the delay, but as suggested on the last post - here is the third post.

Common Ragwort (Senecio jacobaea) in its first year stage creates an immature ragwort plant that resembles a small rosette of between 5 and 15 centimetres across with no flowers. In the second year, it pushes forth a green stem that can reach up and over 1.5 metres high (I know the blasted plants are higher than I am) with the yellow flowers at the top. The photo below shows a recently extricated plant. 

The third photo of this blog (see below) will show the scale of the plant, however it is possible to see how the plant in its second year develops most of its energy budget to create the huge stem with frond-like leaves.

The root is considerably small compared to the length of the stem. You don't have to imagine these plants as sails as you can see them from late July along the sides of single and dual carriageways - the shallow roots help the stem tot sway but not snap. This plant's anatomy reminds me of the huge trees in the tropical rainforests as they also have tall trunks and relatively short roots. This may be due to the fact that both plants exploit poor soils to create huge plants to increase the chance of their progeny surviving; Senecio jacobaea is a natural plant of semi-natural grasslands and colonise well drained and sandy soils. The plant can be an indicator of where sandy soils exist in a field. The small root is also useful in the plant's downfall, the ragwort fork has small tines, and when inserted at the bast of the plant, can act as a pivot for felling the large stem.

Senecio jacobaea has other tricks in its biological arsenal. The flower heads and vegetative parts of Senecio jacobaea have an allelopathic effect on the surrounding vegetation by suppressing the competition from other plants - so that the Common Ragwort can colonise an area. This can be seen by the creation of stands or swathes of Common Ragwort. As seen in the photograph below, the ragwork fork is shown for scale.

With various studies, it has seen that the seeds can travel from the parent plant of under a metre to over five metres. A plant can hold from 4,760 to 174,230 of seeds per plant. After flowering, the plant dies relying on the seeds to increase the invasion and the potential seed bank. The seed bank, the soil below the plant, can be affected by animals, failed germination, fire, mechanical, pathogens, physiological death, predation, rainfall dispersal, above ground and sub-soil water flow and wind.

Yes, it can be said that Senecio jacobaea or Common Ragwort can reduce the quality of a pasture through allelopathy and the decomposition of the leaf litter; it has the potential to kill many agricultural and pastoral animals; and finally it has a crucial part in providing a suitable food source and habitat for many invertebrates...as the Defra document states "It should be expected that some common ragwort will continue to occur in such swards and will fulfill its role in the ecological dynamics of well-drained grassland ecosystems."

If anyone is interested, please either email or add a comment, I can provide sources of the reports quoted in the blog entry above.