. Textbook of pastoral and agricultural botany, for the study of the injurious and useful plants of country and farm. aint-brush. It propagates very freely byrunners, as well, as by feathery fruits. It is now spread over large areasof Maine and other New England states, in northern Pennsylvania, asat Eaglesmere, where a field of it was noted by the writer in full bloomon June 22, 1905. WEEDS AND WEED CONTROL 245 Means of Distribution.—When once introduced, weeds migrate ina number of ways by natural and artificial means. The natural migra-tion of weeds is favored by the possession of runners (
. Textbook of pastoral and agricultural botany, for the study of the injurious and useful plants of country and farm. aint-brush. It propagates very freely byrunners, as well, as by feathery fruits. It is now spread over large areasof Maine and other New England states, in northern Pennsylvania, asat Eaglesmere, where a field of it was noted by the writer in full bloomon June 22, 1905. WEEDS AND WEED CONTROL 245 Means of Distribution.—When once introduced, weeds migrate ina number of ways by natural and artificial means. The natural migra-tion of weeds is favored by the possession of runners (slender radiatingbranches), by elongating rootstocks, by running roots, by seed-throwingapparatus, by having fleshy edible fruits with hard seeds, by flying seeds,and winged fruits, by drifting over frozen ground, or snow, as tumbleweeds, (Fig. 100), by means of water-carried seeds, by attachment to thehair and fur of animals by means of hooks and other devices. The artifi-cial means are as follows: Roots, rootstocks and bulbs are sometimescarried from field to field and from farm to farm by plows, harrows and. Fig. 101.—Extensive patch of bouncing bet {Saponaric officinalis) along an unusedrailroad siding across Hackensack Meadow, July 15, 1916. cultivators. Seeds and other plant parts are carried away in the ball ofearth surrounding the roots of nurserystock. They are entangled inpacking material, in the waste from woolen mills, as ihe storksbill {Erod-ium), in hay, in commercial seeds, which is one of the most frequent waysof weed introduction. Weeds are carried along by the disturbance of theair through the passage of trains (Fig. loi) and automobiles and on theserapid means of conveyance. Weeds have been introduced as useful orornamental plants which have later escaped from cultivation. Theyhave been introduced in ballast and along with the packing of commercialarticles. 246 PASTORAL AND AGRICULTURAL BOTANY Lines of Travel.—The lines of travel of weeds are of interes
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