THISTLES. 35 
6. (a) Flowers purple; no pappus on the seed-like fruits.—True Star 
Thistle or Calthrops (Centaurea calcitrapa, L.). 
(5) Flowers yellow, the oe leaves aaa more or less down the 
stem as wings : ee 7 
7. (a) Fine pappus bavitles re as isn as the os rTienaiivall spines 
of the involucral bracts as long or shorter than the broad basal part of 
the bracts. —Malta Thistle (Centaurea melitensis, L.). 
(0) Pappus longer than the fruit, and the terminal spines on the bracts 
much longer than the basal portions. —St. Barnaby’s Thistle (Centaurea 
solstitialis, L.). 
Carduus arvensis, L. The perennial Corn Thistle. This is commonly, 
but erroneously, called the Canadian or Californian Thistle. It is a native 
of Europe, Asia, and Africa. This is one of the greatest pests of both 
arable, and still more of pasture land, and fortunately is the only one 
of the Trur TurstLEs that is perennial. It grows on almost any soil. It 
can be kept down to a slight extent on pasture land by close-penning sheep 
on infested spots, when the stems are eaten down and trampled off. Freely 
pastured sheep usually leave it untouched unless pressed for food. 
Various elaborate remedies have been suggested, but none are as effec- 
tive as ploughing the ground, raking out and burning the rhizomes, and 
keeping the land under root crops and extra clean cultivation as long as 
may be required. Seeding on neighbouring waste land, roadsides, &c., 
must be prevented, since otherwise the seeds blow in again. In the soil 
the seeds do not appear to last for more than one or two years at the 
outside. The underground parts are weakened by frequent cutting, and 
still more by hoeing or hand-pulling, especially if the latter is performed 
after rain, when more of the rhizome comes up. When the land is once 
cleared, care should be taken not to reintroduce the plant with impure 
agricultural seed, or to allow careless neighbours to do so. 
This plant can be told from most other thistles by its narrower leaves, 
more slender stems, and smaller heads of flowers, as well as by its creeping 
underground “roots.” 
The annual thistles are less injurious, and more easily eradicated if 
properly treated. All the annual thistles will develop as biennials under 
favourable circumstances, or if flowering is prevented by topping. The 
earlier they are dealt with the better. If the hoe is passed through the 
seedlings below the hypocotyl, that is at or below the surface of the ground, 
they die, and two hoeings early in the season should be sufficient to keep 
a crop clean. On pasture land, it is better to wait until the plants have 
attained an appreciable size, but still show no signs of flowering, because 
wherever the pasture is dense the seedlings fail tc establish themselves. The 
plants should be spudded out, taking care that the cut is made well below 
the surface of the ground. If not too large, the plants shrivel without 
flowering. 
On a small scale, hand-picking of seedlings is effective. especially after 
rain, when they usually come up whole. It is no use clearing land unless 
attention is also paid to the borders of fields, roadsides, and to waste 
places, especially round the farm buildings and in the home paddock, since 
the continual in and out traffic is peculiarly liable to spread weeds from 
such a centre of infection. 
Much has been said by interested persons as to the value of thistles as 
fodder in times of drought, and even in times of plenty. They have a 
slight fodder value, especially in the form of silage, and the large milk 
thistle is about the best for this purpose. ‘To cultivate thistles for fodder 
