MAN DISPERSES SEEDS AND PLANTS. 
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52 . Man takes plants westward, though a few migrate 
eastward. — So far as man’s agency is concerned, the 
direction for plant migration is generally westward, in 
the course taken by himself. In case of two hundred 
kinds of weeds named by the United States Department 
of Agriculture, one hundred and eight species are of 
foreign origin. Three notable samples of weeds in the 
United States have gone from the west to the east, carried 
in seeds of grasses or clovers. These are Rudbeckia hirta, 
Artemisia biennis , Plantago aristata. To these Mr. Dewey 
adds buffalo bur, Solanum rostratum , squirreltail, Hordeum 
jubatum, false ragweed or marsh elder, Iva xanthifolia, 
Franseria hookeriana, alfalfa dodder, Cuscuta epithymum. 
Above I have barely mentioned a few of the methods 
by which man is an unwilling agent in distributing plants. 
Large volumes could be filled with statements of man’s 
more or less carefully planned attempts to transport seeds 
and living plants from one part of the world to another. 
