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wheat, 53 flax, 43 buckwheat, and 91 ragweed seeds. The wind was blowing at the rate of 20 miles per hour. There can be no question but that a drift holds a large number of weed seeds. Along our highways one may find, where the snow has drifted, the ragweed and thistle growing in large numbers.

Fig. 8. The seed of vegetable oyster plant scattered by the wind. Fig 9. Various “seeds” scattered by drifting snow. A, small ragweed; B, sunflower; C, foxtail.

Water.—A number of our very troublesome weeds are carried by the water. This is notably true for the “seeds” of docks. Three of the sepals or outer floral envelopes of the flower of the docks each bear an enlarged body called the tubercle, which is hollow. This body, combined with the calyx, enables it to float on the water. During our recent wet years, it has been noticed by farmers that these docks are unusually common on low ground, having been carried thither by water. Many seeds, like those of pepper grass, are mucilaginous. In


Fig. Io. The “seed” of a common sedge surrounded by an inflated sac, scattered by the water. (Beal.)

walking through a patch of this weed
with moist shoes, many seeds are
caught and carried to new situa-
Wild oats and many other seeds
may be found on land subject to
overflow. These seeds are scattered
in a mechanical way.
Animals.-Many of our weeds are
scattered by animals, this being
brought about either because the
plants offer something for food, as in
the ground-cherry, black nightshade,
dandelion and thistle, or because the
fruit is accidentally carried. Exam-
ples of the latter class are Spanish
bayonet or bootjack, cocklebur or

stick-seed, burdock, sandbur, and tick trefoil. Explosive Properties.—We have but one weed the

seeds of which have explosive properties. This is the

yellow sorrel (Oxalis), which is com

mon in some fields. The outer coat of the seed separates and the seed is forced out of the pod as though

shot from it.

Creeping Mechanisms.-The needle-grass is important as a weed at times only, in gravelly pastures. The seed of this grass has a sharppointed callus and hairs above this point that project obliquely upwards.

this way the seed not only creeps

Fig. 11. The seedlike - - fruit of arrow-head, It has a long, twisted awn, and in scattered by water.



over the ground, but becomes buried. The wild oats also has a creeping arrangement. Man as an Agent.—Nursery stock is responsible for the scattering of a number of weeds and weed seeds. The scattering of quack grass in this way had been reported to us. Canada thistle, ox-eye daisy, and other perennial weeds are known to have been carried and scattered by this means. Wool.—Wool is often responsible for the introduction of a great many different weed seeds. Around woolen mills it is common to find Fuller's teasel, which is so commonly used in carding of wool. The western storksbill o (Erodium cicutarium) no doubt owes its Fig. 12. Seeds origin in this section to having been :*::::"... o: introduced with wool. There is con- containing seeds of Stant danger when getting live stock Poison ivy, ... etc. from the o o # weeds of (U. S. Dept. Agrl.) this character will be introduced. Some members of the borage family like Lappula floribunda have been scattered in this way. Cultivation.—It is not uncommon to find that weeds are carried from one field to another by cultivators or plows. This is particularly true of quack grass and Johnson grass. Impure Seed.—Many bad weeds are introduced with impure seed. We have during the past season received many specimens of weeds found in clover meadows. These weeds were undoubtedly introduced with clover seed. In nearly all instances the farmers stated that they had not observed these weeds before. Not all of the clover seeds sold by seed merchants contained these weed seeds, much of it being of good quality.


As examples of presence in clover fields of weeds introduced with seed, a few selected areas observed July, 1903. may be cited. Three areas Io feet square situated southwest of Ames averaged 53 vigorous specimens of ribgrass. Two areas 12 feet square upon a farm near Mar

Fig. 13. Goldfinch eating the seed of dandelion. (U. S. Dept. Agrl.)

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Fig. 15. Burdock head with many “seeds” scattered by animals.

(Dewey, U. S. Dept. Agrl.)
Fig. 16. “Seed” of pitchforks, Spanish needle, scattered by animals.

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athon averaged six ribgrass and three wild carrot plants. In another piece of the same field not cut at Marathon,

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Fig. 17. Seeds scattered by explosive properties. A, geranium; B, wood sorrel; C, pod or common vetch. (U. S. Dept. Agri.)

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