220 . THE POPULAR SCIENCE MONTHLY. 



columbine is particularly well adapted for having its seeds scat- 

 tered by the wind. They are held in open seed vessels surmount- 

 ing a slender stalk which, although nodding at flowering time, 

 has become upright. A slight breeze easily shakes this stalk, 

 causing the seeds to be thrown for quite a distance. The poppy 

 throws its seeds in a similar way, and the little eaves which stand 

 over the holes in the pod are even said to close in wet weather, 

 not allowing the seeds to escape. 



In many wonderful instances the ripe pod projects its seeds 

 forcibly into the air. In some of our wild violets the pod, after 

 dehiscence, consists of three spreading valves, each shaped like a 

 boat, bearing within several seeds which are pear-shaped, hard, 

 and smooth. In drying, the valve walls contract, approach each 

 other, and squeeze out the seeds, which are thus thrown several 

 feet. Our wild witch-hazel throws its seeds often to the distance 

 of thirty feet. Many of us recollect the sudden bursting and coil- 

 ing up of the pods of the " touch-me-not," whose yellowish, spurred 

 flowers are so common in moist places. The object of this action 

 is to expel the seeds. Curious is the case of the squirting cucum- 

 ber of southern Europe. The ripe, cucumber-like fruit is greatly 

 distended by its contents. At a slight touch, as from a browsing 

 animal, it breaks from the stalk, and through the hole thus formed 

 the pressure of the elastic walls forces the seeds in a viscid liquid 

 for twenty or thirty feet. 



Fruits that do not split open are invariably scattered by ex- 

 ternal means, inanimate and animate. Of inanimate agencies 

 the wind is far of tenest employed, and seeds have evidently found 

 it extremely efficient, judging from their many adaptations for 

 wind dispersion. The seeds of our elms, maples, pines, etc., are 

 surrounded, as we know, by thin expansions called "wings," 

 whose purpose plainly is to present a large surface for the wind 

 to act upon. Wings are characteristic alone of trees or tall 

 shrubs, and never occur on low herbs, where they would clearly 

 be out of place. Instead of a wing, a tuft of hairs frequently 

 serves the same purpose. A common example is furnished by 

 the milkweed, whose seed is surrounded by a spreading " pappus " 

 of long, silky hairs. The dandelions and thistles have adopted 

 this means of distribution, and this explains their abundance 

 everywhere. In the smoke-bush of our gardens only a few 

 flower stalks bear fruit, the rest become slender and feathery, 

 forming a light network which is borne along in the wind, carry- 

 ing the few small fruits which have formed. 



Flowing water transports many large nuts, some depending 

 upon it almost exclusively. Drifting along in our fresh-water 

 streams one may often see the " key fruits " of the red maple, and 

 the soaking they thus receive must further germination. The 



