I. Marsh Sow-thistle (_S. palustris_), now all but extinct, and found only rarely in the Eastern counties of England and Kent. It is taller-growing than _arvensis_, the stem sometimes reaching nine feet, but the flowers are only half the size of that species.
II. Common Sow-thistle (_S. oleraceus_). A common annual in every field and waste. General character of plant very similar to _arvensis_, but smaller. Stem, two to three feet in height, without (or rarely with) the glandular hairs. Flower-heads many, not exceeding an inch in diameter. June to September.
Name supposed to be derived from the Greek, _sonthos_, hollow, in reference to the fistular stems.
=Grass of Parnassus= (_Parnassia palustris_).
It is a singular thing that some of our most beautiful plants grow in the most unpleasant places. We remember a backwater of the River Thames that used to receive the waste waters from a large soap-works, and in the evening, when this waste was poured out, the stench arising from the ditch was unbearable. Yet, with its feet in this vile liquid, the Meadow-sweet grew luxuriantly, but truth compels us to add that its sweetness was thrown away; it could not overcome the other smell. Black bogs and mossy swamps are the particular haunts of floral beauties, such as the marsh violet, the bog buckbean, the marsh marigold, the bog pimpernel, the sundew, the bog asphodel; and it is in such resorts we must look for the Grass of Parnassus, a plant so pretty and elegant of form that it must first have grown upon Mount Parnassus. At any rate, the English name is a mere translation of that given to it by Dioscorides, among the six or seven hundred plants mentioned by him.
It is a perennial, with a stout rootstock. With few exceptions the leaves are radical; they are heart-shaped, smooth, with untoothed edges, and on long stalks. The flowering stems are long, angular, with a stalkless leaf nearly half-way up. At the summit is the solitary large flower. The fine thick sepals are slightly conjoined at their bases, the petals white, veined and leathery. The ovary is large, and on its summit, without the intervention of a style, are the four rayed stigmas. Around the ovary are five stamens--there should be ten, but five have been transformed into scales, which alternate with the perfect stamens, and are fringed with white hairs, each ending in a yellow knob; on the face nearest the ovary each scale bears two small honey-secreting glands. The perfect stamens ripen in succession, and as each becomes mature, it raises itself until the anther comes on top of the stigma, but with its back to it. The front opens and discharges the pollen away from the stigma; but it falls where insects seeking the honeyed glands (using the ovary as a perch) will get it upon their forelegs, and so attach it to the stigmas of the next flower they visit.