growing are crowded and starved to death. A very
small proportion fall on good ground, and succeed in becoming
fruiting plants. A large plant of purslane produces one million two
hundred and fifty thousand seeds; a patch of daisy fleabane, three
thousand seeds to each square inch of space covered by a plant. The
genuine student will not be satisfied till he has selected several
different kinds of plants and counted, or estimated, the number of
seeds produced by each, or the number of seeds furnished to the area
covered by one or by several plants.

CHAPTER VIII.
MAN DISPERSES SEEDS AND PLANTS.

In describing the various means by which plants are dispersed, people
are very likely not to mention the aid supplied by man, or to speak
of his efforts as artificial or unnatural, forgetting for the time
that man so far appears to be the crown of earthly existence, and
that his works are a necessary part of a complete world.

51. Burs stick to clothing.--Late in summer or in autumn, who is there
who has not returned from a walk along the river or from a tramp through
thickets or the open woods, to find large numbers of half a dozen
kinds of seed-like fruits sticking to his clothes? When ripe, these
fruits usually separate from the parent plant very easily, by a joint
or brittle place well provided for in the early part of the season.
In pursuing your way you rub off a portion of these fruits, and at
the end of the journey, or before, you sit down in some comfortable
spot and deliberately pick off the unwelcome stick-tights. At such
times you have been the means of transporting seeds, and you have
left them scattered about ready to grow. If you ever were so fortunate
as to live on a farm, you must have seen your father or his hired
help carefully look about the field or the wood lot and remove all
the bur-bearing plants that could be found before turning in his flock
of sheep or the colts and cattle; for if this were not done, he knows
that hair and mane will surely be disfigured, and that the wool will
be rendered unsalable. In removing the weeds he defeated the plans
of Nature in her devices for sowing seeds.

The agency of man in the distribution of plants exceeds in importance
that of all other means combined. He buys and sells seeds and plants,
and sends them to all parts of the habitable globe. He exterminates
many plants in large areas, and substitutes in large measure those
of his choice. Mixed with seeds of