THISTLE (AS. Pistc/, OHG, distula. distil, Ger. Distel, thistle). A popular name for va Flow; plants of the natural order Composite. They have either stout, spiny herbage or flower ing bracts. They are widely distributed, mostly a, weeds. In the United States the name applies to the species of Cnicus, Carduus, Onopordon, Centanrea, and Sonehus. By some botanists the first two genera are combined under the name Cardims. The principal distinction between these two is that Cnicus has plumose pappns and hence is often called plume thistle. while Car duns has bristly pappus. The species belonging to the other genera are all introduced from the Old World. The pasture thistle (Cnicus pi/ali bis), yellow thistle (Carduus horridulus), bull thistle (Carduus laneeolatus), and others are common and troublesome in pastures and on roadsides. Cardaus arvensis, the so-called Can ada thistle, a European species, is one of the ino,t troublesome and difficult to eradicate of all. It is a slender perennial, one to three feet high. with rather small, rose-colored flowers. It spreads prin cipally by its spreading rootstocks. but can be eradicated by persi,tent cultivation. The heads are imperfectly dhecious and not all produce seed.
Among the other common European thistles found in the United States is the milk thistle (Silybum.
ilarianum), a biennial plant four to six feet tall, The leaves are some times used as salads, or as pot herbs. The roots,
for which it was formerly cultivated, were used like salsify. The blessed this tle (Carbeniabenedieta). native of Asia, was for merly considered to have medicinal properties. It resembles the star thistle (Centanrea). of which there are many species, the best-known of which are Centaurea Caleitra pa and Centourea Cyanus, the blue-bottle thistle. The cotton or Scotch this tle (Onopordon Acanthium) is recognized by its deeply honeycombed receptacle and cottony or woolly leaves. It is said to be the emblem of Scotland, but Cnicus aeaulis, a stemless thistle common in Scotland. seems more worthy this designation. The Carline thistle (Carlina rulgaris) is a rather troublesome weed in poor soils in Europe, and was named Carline thistle because Charlemagne, according to tradition, used its roots as a cure for the plague. Species of Sonehus are called sow thistle, of which three are found in the United States, Sonchus olera ceus, the common sow thistle. Sonehus asper. the spiny leaved sow thistle, and Sonehus arrcnsis, the field sow thistle. Other plants of different orders are sometimes called thistles, as species of Dipsaens (see TEASEL) and blue thistle (Echivni vulgare), the latter belonging to the order Bo•aginacen. See Plate of TANSY. ETC.