A GROUP OF AIRSHIP SEEDS 



Ready to start on the great adventure 



Of the many methods of seed dispersion that of using the 

 wind as carrier is one of the most common and most effective. 



In the picture opposite we have an interesting group of such 

 airship seeds. The centre is occupied by a spike of the great 

 willow-herb, or fireweed, whose forty long pods conta'ned about 

 twelve thousand seeds On a dry day it is a pretty sight to see 

 these pods splitting open, their four slender divisions cui 

 quickly but gently outward into the form of a cross, and the 

 imprisoned down instantly fluffing out as if delighted to find 

 freedom. The seeds lose no time in starting on their momentous 

 journey, but eagerly commit themselves to the first passing breeze. 

 The launching of these tiny, crowded airships is in open situations 

 usually attended by few mishaps, and away they sail, each freighted 

 with a potential fireweed that may by and by bloom in splendor 

 on some distant clearing. These seeds are extremely light and 

 buoyant. Twelve hundred of them weigh less than one grain, 

 and in a still room, experiment showed that on the average the 

 seeds took forty seconds to fall eight feet. The slightest upward 

 breath of air sent them soaring, and in the open there is no doubt 

 that they rise to great heights and travel long distances. 



On the left of our picture are opened milkweed pods. Each 

 held about fifty large, brown seeds. These pods split open along 

 one side only, and at first no silk is seen, for the flat seeds overlap 

 one another like the scales of a spruce cone, but as drying pro- 

 gresses the elasticity of the compressed hairs pushes up and out 

 seed after seed to be whirled away by the wind. The weight of 

 each is more than one hundred times that of a fireweed seed, yet 

 the sustaining power of its large and beautiful parachute is such 

 that it has one-fifth the buoyancy of the lighter seed. 



To the right are five disintegrating cylinders of the long- 

 fruited anemone. While still intact, all the seeds about two 

 hundred and forty to each are on the outside, arranged in well- 

 ordered spirals with the wool tightly packed within. When the 

 expansive pressure of this drying wool finally bursts the neat 

 cylinder, the crinkly wool separates into little tufts with a seed 



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