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.
As in the case of other typical marsh plants this plant has been found in Interglacial and Neolithic deposits. It is found to-day in Arctic Europe and Siberia. The Marsh Thistle is known in all parts of Great Britain, even ascending to 2400 ft. in the Highlands.
The name Marsh Thistle indicates to some extent the range of this species, which is so familiar a member of all marsh floras, with its tall tufted heads of purple bloom. But it is really common to all wet ground, growing in damp hollows in meadows and along the margins of lakes, rivers, and pools of all descriptions.
The Marsh Thistle is one of the tallest thistles, erect, branched at the top and angular, clothed with white hairs and with numerous spines. It has usually one main stem, which is purple and green. The leaves run down the stem, and are rough, deeply divided to the base, and beset with numerous brownish prickles, stalkless and turned down, lance-shaped, with blunt broad teeth, and a palish-green midrib. The margins of the leaves bear the spines, which are purple at the base.
The stem is winged with interrupted, spinous, rudimentary leaves, which serve to protect it.
The flowerheads are violet in an egg-shaped involucre, with egg-shaped to lance-shaped phyllaries, which terminate in a point and overlap. The florets are tufted and clustered, and rather small, and the involucre is slightly webbed. The limb of the corolla is 5-lobed to the middle.
This graceful plant may be 3 ft. high. It is rarely in flower before July. Biennial, it is herbaceous and propagated by seeds.
Marsh Thistle has a capitulum intermediate between C. arvensis and C. lanceolatus, in so far as it is possible to reach the honey, and in the variety of visitors. The throat of the corolla is 2 1/2 mm. The florets are tubular and complete.
It is visited by Apis mellifica, Bombus, Andrena, Halictus, Mega-chile, Lindenius, Eristalis, Volucella, Syrphus, Sicus, Pieris, Hesperia, Satyrus, P/usia, Agrotis, Strangalia.
The achene is narrow, and provided with a feathery pappus for wind dispersal.
This fine composite is a peat-loving plant, requiring a humus soil, and growing in peaty bogs, etc.
Two fungi, Puccinia hieracii, P. dioicae, infest it. Two beetles, Psylliodes picina, Larinus carlinae, a moth, Coleophora therinella, are to be found upon it.
The second Latin name refers to its habitat. It is called Boo-thrissel, Moss-thistle, Red and Water Thistle. It was said to counteract the powers of darkness, and in Esthonia they place it in ripening-corn to drive away malignant demons. Elf lock, a disease in Poland amongst the poor, said to be due to evil spirits, disappears when one buries thistle seeds. If thistles are seen in a dream it is a good omen. "If the down flieth off Coltsfoot, Dandelion, and thistles when there is no wind it is a sign of rain", and "Chaff, leaves, thistle down, or such light things whisking about and twining round foreshows tempestuous winds". In Suffolk "Cut your thistles before St. John, You will have two instead of one".
The tender stalks, if peeled, are eatable when boiled.
Essential Specific Characters:171. Cnicus palustris, Willd. - Stem tall, erect, purple, hollow, branched above, spinose, winged, leaves not hairy above, decurrent, thorny, brownish, flowerheads purple, small, terminal heads in a cluster, bracts purplish-green, ovate-lanceolate, corolla limb 5-fid to middle.