Most people are familiar with the various novel methods that are employed by plants in the distribution of their seeds. Many seeds are winged so that they are carried by the wind, others are contained in edible fruits to attract bids and animals - the seeds passing through the digestive tracts uninjured and thus are transported considerable distances to germinate and grow in a new locality. Still others are supplied with barbes that become attached to the bodies of animals that may be passing, and others equally interesting have other means of "locomotion".
That various ingenious mechanisms are also employed in the release of the seeds is not so well known. Apparently wild flowers seeds grow best if planted in the autumn. Many of them however are forced, for want of sufficient moisture in the fall, to flower in the spring. In such cases the seeds, although they may be formed early in the year are usually carried over the dry summer season by the parent plant.
A good example is the western anemone (Pulsatilla occidentalis). The flower comes very early in the season, often pushing its way through the edge of the receding snowdrifts and remain in bloom only a few days. The fluffy silver gray seed-heads are carried all through the summer however, the winged seeds not becoming sufficiently loosened on the stalk to be carried away by the wind until late season.
The avalanche lily (Erythronium montanum), employ another clever method. The seeds are formed in triangular pods that are carried erect at the top of a slender stalk. When the weather becomes dry these open but the seeds remain loose in the capsul and do not fall until the rains begin again in the late summer. With the rains conditions are ripe for planting and the seeds are mature and ready so the dry stiff stalk absorbs moisture and becomes soft. Immediately the heavier seed pods bends the stem and turns over, spilling the loose seeds on the moist soil.
The pods of several other plants remain closed until conditions are propitious and then, responding to the changed climate open suddenly and with sufficient force to broadcast the seeds to the four winds. Still others like the knobcone pine grow best after a fire. The cones will not open until heated by fire to a point well beyond that possible by the sun. So long as there is no forest fire the knobcone pine cones are wasted, they never open.
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