11. Some seeds and seed-like fruits are furnished each with a balloon, or a sail, or with grappling hooks. (Dandelion, sticktights, burdock.)
12. Some remain with the dead plant long into winter, and when torn off by the wind or by birds, drift for long distances on the snow, often from one farm to another. (Pigweeds.)
13. Some have creeping root-stocks or tubers. (Quack-grass, nut-grass.)
14. Some defend themselves with forks and bayonets. (Thistles.)
15. Most of them are disagreeable in taste or odor, so that domestic animals leave them to occupy the ground and multiply. (Jamestown weed, stink grass, milk weed.)
16. Plants with stout roots are sometimes passed over by the harrow or cultivator.
HOW ARE WEEDS INTRODUCED AND HOW ARE THEY SPREAD?
1. By live stock, carried in the hair or fleece or carried by the feet; in some instances passing alive with the excrement.
2. By unground feed-stuff purchased.