Senecio aquaticus (MARSH RAGWORT)

Senecio aquaticus (MARSH RAGWORT) is a form of S. Jacobaea, common on the sides of rivers and ditches throughout the country, growing freely at an elevation of 1,500 feet above sea-level, in the Lake district and resembling the common Ragwort, but usually of laxer growth and readily distinguished by its less divided, longer-stalked leaves and larger heads of flowers, which are 1 to 1 1/4 inch in diameter.

All forms of this genus are not of beneficial use, and one at least has lately been found to be distinctly harmful, for Molteno disease, a cattle and horse disease prevalent in certain parts of South Africa, has been definitely traced to the presence of a poisonous alkaloid in S. latifolius, a near relative of the Common Groundsel.

Some botanists refer the genus Cineraria to the same order as the Senecio; these differ from Senecio in the achenes of the rayflorets being winged. The beautiful spring-flowering plants cultivated in greenhouses as Cinerarias belong, however, to Senecio, and have been obtained by horticulturists by intercrossing with each other a number of the Canary Island species, such as S. populifolius, S. Tussilaginis, etc. The deep blue colour of some of the garden varieties of these plants is singular in the genus, and not at all common in the family.

From the report of the Board of Agriculture's Chief Veterinary Officer (1917):

'It is not generally recognized that the common British Ragwort is poisonous to cattle. This probably arises from the fact that poisoning under natural conditions is a slow process, that is to say, an animal does not receive, and could not eat enough of the weed at one meal to cause acute poisoning. On the other hand, the poison is cumulative in its action; with continuous doses the amount of poison which becomes available is sufficient in time to cause very serious symptoms which often end in death. Much more attention has been given to the subject of poisoning by certain species of Ragwort in South Africa, Canada, and New Zealand, and in certain districts where it is commonly met with it was believed to be a disease of cattle until its actual cause was discovered. Thus, we find such names applied to it as Pictou, Winton, and Molteno disease. The following represent broadly the circumstances of the cases which have recently come to the notice of the Board. Pastures containing a considerable proportion of the weed were cropped in the hope that the comparatively early cropping might help to get rid of it. The crop was made into hay, and owing to the prolonged spell of cold weather and the scarcity of other feeding stuffs, this was fed later and in considerable amount to animals at pasture.

'The actively poisonous agent in the plant seems to be one or two more alkaloids which have been extracted in more or less pure form from various species of Ragwort.... Some of the animals fed on the Ragwort died in a few days after the first appearance of definite symptoms. In others the symptoms continued for a month or more and deaths occurred at later dates. It would appear also that although animals which had received a toxic amount of Ragwort over a certain period may seem healthy at the time when feeding on the material is discontinued, they nevertheless develop active symptoms of poisoning and die at a later period. Thus in the cases investigated some of the animals did not show definite symptoms until twelve days or more after the feeding with Ragwort had been discontinued. In the early stages the animals have the appearance of being hide-bound. Later, they walk with a staggering gait, some appearing to be partially blind or heedless of where they go. Later they may become very excitable, and will charge at anyone who approaches them. In some there may be diarrhoea, but usually constipation is so marked that it causes violent straining. The pulse is weak and rapid, but the temperature remains normal. ... There is no cure, and prevention resolves itself into removing the Ragwort from the forage, or eradicating it from the pastures.

          McGovern makes the following recommendations for eradicating the weed:

'Ragwort may be exterminated by preventing the plant from seeding. This may be done in the following ways:

'(a) By grazing infested land with sheep in the winter and early spring.

'(b) By cutting the plants in the flowering stage either

-- '(i) Twice, the first cut being made early inJuly, and the second about six weeks later, there being no necessity to gather up the cut portions; or

-- '(ii) Once only, cutting being done late in July or early in August. The cut portions of the plants must be gathered up at once and burnt.

'(c) By pulling the plants, if circumstances permit, preferably early in July, when there is no need to collect and burn the pulled plants. If pulled later the plants must be collected and burned to prevent seeding . . .

'It is not certain that sheep are absolutely immune to poisoning by Ragwort. Probably the flowering season -June, July, and early August - is when Ragwort is most actively poisonous.'