This section is from the book "Wayside And Woodland Blossoms", by Edward Step. Also available from Amazon: Wayside And Woodland Blossoms: A Guide To British Wild-Flowers.
We have selected this very vulgar plant as a familiar example of a genus that contains some very striking species. They all produce composite flowers, but in this common weed the ray-florets are usually wanting, and consequently the few cylindric flower-heads have a very singular appearance. The leaves are deeply cut, the lobes irregularly toothed. The flowers are succeeded by the well-known fluffy pappus attached to the seeds, which has enabled the plant to become one of the most widely distributed in all temperate and cold climates. It is to this hoary head of seed-bearers that the genus is indebted for its name, which is derived from the Latin Senex - an old man.
Senecio vulgaris. - Compositae. -
- Gramineae. There are other eight British species, of which the most frequent are briefly noted below.
I. Mountain Groundsel (S. sylvaticus). Leaves similar to S. vulgaris, but divisions more accentuated. When the ray is present it is rolled back. The flower-heads are more numerous than in vulgaris. Plant with unpleasant foetid smell. Dry upland banks and pastures. July to September.
II. Stinking Groundsel (S. viscosus). More objectionable-smelling than the last. Leaves broader, more divided, glandular, hairy and viscid. Plant much branched and spreading. Flowers larger: rays rolled back. Waste ground. Local. July and August.
III. Ragwort (S. jacobaea). Stem thick and leafy, 2 to 4 feet high, somewhat cottony, with clusters of large golden yellow flower-heads with spreading rays Leaves finely lobed and toothed. Waysides, woods and pastures. June to October. Very plentiful.
IV. Hoary Ragwort (S. erucifolius). Similar to the last, but the stem more loosely cottony; the segments of the leaves more regular and less divided; rootstock creeping. Hedges and roadsides. July and August.
V. Water Ragwort (S. aquaticus). Like S. jacobaea, but of lesser growth Flower-heads larger, leaf-stalks longer. Wet places, riversides, ditches. July and August.