This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Fruits of this common paludal type have been found amongst others in Interglacial deposits at West Wittering, Sussex. It is found in the North Temperate Zone to-day in Europe and Siberia. It grows in every part of Great Britain except N. Aberdeen, ascending to 1500 ft. in the Lake district.
Water Ragwort is a marsh plant, growing commonly in wet meadows that are continually submerged. But it also grows by the sides of lakes and rivers, and wherever there is water of a permanent nature. In similar spots grow Great Water Chickweed, Marsh Thistle, Water Mint, Alder, Crack Willow, and other hygrophytes.
The stems are not so stout as in some other species of Ragwort, but several small ones grow out of a short, often prostrate one, or the plant may be tall and erect, like Common Ragwort. The radical leaves are oval-oblong, entire, or rarely toothed, clasping, simple below, and smooth. The stem-leaves have the lobes larger upwards and deeply divided.
Photo. C. Allen - Marsh Ragwort (Senecio Aquaticus, Hill)
The flowerheads are rayed and spreading, with elliptical florets, borne on slender flower-stalks in a corymb. The corymb is very loose and variable in the number and arrangement of the florets. The fruit is smooth and ribbed.
The plant is 2-3 ft. high. It blooms in July and August. It is a herbaceous perennial and propagated by division.
The flowerheads are large and as conspicuous as in the Hoary Raowort, and the same arrangement of the flower holds good. The ray florets are female or absent, the disk florets being complete. The achenes are furnished with abundant silky pappus and adapted for wind dispersal.
Marsh Ragwort is a peat-loving plant, and requires a more or less damp and peaty soil, such as that which is obtained in a marsh or bog.
Marsh Ragwort is infested by a cluster-cup fungus, Puccinia senecionis. A moth, the Wormwood Pug (Eupithecia absynthiata), feeds upon it.
The second Latin name refers to its aquatic habitat.
Ragwort is known in Ireland as "Fairies' Horse", and was said to have been sought for by witches when taking their midnight journeys. Burns in his "Address to the Deil" makes his witches "skim the muirs and dizzy crags on ragweed hags "with "wicked speed". A similar legendary belief prevails in Cornwall in connection with the Castle Peak, a high rock south of the Logan Stone. "Here", Mr. Hunt writes, "many a man, and woman too, now quietly sleeping in the churchyard of St. Levan would, had they power, attest to have seen the witches flying into the Castle Peak on moonlight nights, mounted on the stems of the Ragwort." "Fairies' Horse" was applied because fairies were supposed in Ireland to ride to their scenes of merry-making on Ragwort. It was a Manx preservative against all infectious diseases.
Essential Specific Characters:167. Senecio aquaticiis, Hill. - Stem tall, radical leaves petiolate, subentire, glabrous, flowerheads large, yellow, in loose corymbs, rays spreading, fruit glabrous.