CHAPTER XXII
DISPERSAL OF SEEDS
It is to the plant's advantage to have its seeds distributed
as widely as possible. It has a better chance of surviving in the struggle for existence. It gets away from competition.
Many seeds and fruits are of such character as to
increase their chances of wide dispersal. The commonest
means of dissemination may be classed under four heads:
explosive fruits; transportation by wind; transportation by birds; burs.
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Fig. 249.—Explosion of the Balsam Pod.
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Fig. 250.—Explosive Fruits of Oxalis.
An exploding pod is shown at c. The dehiscence is shown at b. The structure of the pod is seen at a.
Explosive Fruits.—Some pods open with explosive force and discharge the seeds. Even bean and everlasting peas do this. More marked examples are the locust, witch hazel, garden balsam (Fig. 249), wild jewel-weed or impatiens (touch-me-not), violet, crane's-bill or wild geranium, bull nettle, morning glory, and the oxalis (Fig. 250). The
