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The weeds from New England to Illinois are of much the same character. The Ohio and Illinois lists, therefore, will include
most of the weeds of New York and New England.

CHAPTER X.
MIGRATION OF WEEDS

The study of the abundance of weeds and their distribution is one of great importancé to the cultivator of the soil. Many of our common weeds occur from the Atlantic to the Pacific. Many of them are of European origin. Some weeds are native to the soil; others are tropical in origin. It will be found from the list of weeds appended that many of them are common from the Gulf of Mexico to British America. It is also true that Texas has some of its own weeds; that the eastern Gulf states have some peculiar weeds; that the states west of the Missouri River to the Rocky Mountains also have their own characteristic weeds and some localized weeds are found upon the Pacific coast.

It may be interesting to observe in this connection that some weeds require a considerable length of time before they are permanently established and become a part of our flora. In other instances certain weeds are crowded out. During recent years the writer has found very little evidence of the black mustard in this state, most of it being replaced by the charlock, or wild mustard of our oat fields. In Utah the awned brome grass has crowded out the quaking brome grass. In 1898, when the writer visited the region of Salt Lake and Ogden he found quaking brome grass the predominating grass on the hillsides, but now the hillsides are covered with the awned brome grass and very little of the quaking brome grass could be seen.

Our eastern weeds are in a large part native to Europe, but there are a number native to Iowa, while others have come from the South and West. The question of

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