worst weed in grain fields. In cultivated fields it causes very little trouble, as it is as readily destroyed as other weeds; but in fields of spring wheat, especially, much damage is done by this plant. Springing up with the wheat the latter is crowded out, shaded out, and robbed of the food it might otherwise get from the soil. The result is a greatly reduced crop of inferior quality.

Like most of our bad weeds it is an introduction from Europe, but it is so well established now in this country and in the wheat growing sections of Wyoming that where it came from is only of historical interest. How to keep it out of our grain fields is a practical question, and I think one which can be answered.

This is a case where prevention, rather than cure, must be sought. A field well seeded to Cockle, as well as wheat, is practically beyond redemption. The remedy lies in clean seed on clean ground. This is not so difficult of attainment as many suppose. Suspected seed wheat, if it must be used, should and can be cleaned by screening. This should be sown on clean ground. Let the ground known to be full of Cockle seed be used for cultivated crops till the Cockle has been exterminated. To avoid having to fight and endure loss from it every year see that road sides, fence rows and vacant grounds are not maturing plants and seeds to undo all your other work.

This annual may be known by its smooth, opposite leaves, united by their bases, by its rather large pink flowers in a strongly five angled calyx which becomes much enlarged in fruit. It usually grows 18 inches to 2 feet high and branches above.

These characteristics in connection with the figure of

it (Plate V), will enable any one to determine suspected

plants.

CANADA THISTLE,

(Carduus arvensis Robs.)

This is one of the true Thistles and not merely one in name. It has been talked of and written of for years throughout the United States, and as a result it has come to be so dreaded that wherever it has appeared relentless war has been waged upon it. This, however, has not exterminated it, but it has kept it in check. That this commendable vigilance against this foe might not relax, many States have placed this in the list of weeds proscribed by law; in fact, it was among the first, if not the first, against which laws were enacted.

This weed is now in Wyoming. The writer found a patch in a stock yard on a farm near Sheridan in July of this year. It was also reported from there, with specimens, in 1895. It is probable that some effort was made to exterminate it at that point, but it is very probable that it has entered the State at other places.

Every one should be on the lookout for this invader, as it is comparatively easy to dig out a few, but when a large area is infested it is a costly undertaking. I use the words dig out advisedly, for it cannot be destroyed by ordinary methods.

It

It is a perennial plant; that is, it lives for a number of years, dying down to the ground only, each year. is reproduced by seeds, which are furnished with a tuft of hair, that the wind may the more readily carry them long distances. This accounts for the rapidity with which it

spreads, but the difficulty of killing it out where it has become established is quite another matter. Examination reveals the fact that each plant is furnished with a number of long, slender, underground stems, which at intervals give rise to new

above ground stems. This, then, is a second means of reproducing the plant, and gives it its wellknown tenacity of life. Ordinary stirring of the soil only increases the number of individuals, as each piece of the broken up underground stems promptly sends up a new shoot.

that it must not be allowed to seed, otherwise new areas will be infested by the seeds blown away by the wind. To destroy it where established, if the area be large..recourse must be had to some method of cultivating the soil which shall entirely keep down the above ground parts, thus starving to death the underground stems. All underground parts,

PLATE VII.-CANADA THISTLE. Part of a plant, showing leaf and head more in detail.