MUTUAL BENEFITS OF INSECTS AND PLANTS. 159 



abundantly dusted with pollen, yet no fruit sets unless two trees are somewhere 

 near each other, that the pollen of one tree may get upon the pistils of the 

 other. In such cases the flowers of the two trees fertilize each other. The 

 same is said to he true with one stalk of corn in a distant held. 



Most of our cultivated strawberries have perfect flowers, and may he self- 

 fertilized, at least to a great extent; hut the Ilovey, green prolific, and some 

 others, have poor or ahortive stamens. That they may he fruitful, it is the 

 practice to mix the plants witli the Wilson, or some other plants bearing perfect 

 flowers. The bees carry the pollen and take the honey. 



But how is it with the majority of perfect flowers which have good stamens 

 and good pistils in the same flowers? In many of these the pollen is applied to 

 the stigma by insects, and such flowers arc rendered more fruitful by these 

 insects than they would be if the flowers were left to themselves. This has been 

 proved by experiment to be the case in many instances, though some flowers 

 are no more likely to seed with the help of insects than without. Very many 

 of our perfect flowers present or ripen the anthers a day or so before the pis- 

 tils are ready. Such arc the lobelias, campanalus, — most all the compositai 

 which includes about one-ninth of all the flowering plants of this part of the 

 country. The last order includes the sunflower, aster, golden-rod, dandelion, 

 etc. Flowers of spilobrium or willow, herb, and clerodendrou, thrust the sta- 

 men out straight when ripe, while the miniature stigma is curled back when the 

 style straightens. The stigmas are the brides too late for the marriage of near- 

 est relatives, for the pollen or bridegrooms have been carried off by the insect 

 priests, and may be wedded to others not related or not very nearly related. 



Prof. Riley observed a small moth especially adapted to fertilizing a yucca. 

 She laid an egg and theii sipped honey, and so repeated the operation. The 

 plant reared her young insects. She took the honey and transferred the pollen, 

 enabling the plant to set seeds. Insect and plant were useless each without the 

 other. This is sometimes true of the striped cucumber-beetle. She eats the 

 young plants, and later the pollen and honey, but she helps the plants to seed. 



The flowers of martynia trumpet creeper, mimulus catalpa, bladdcrwort, 

 and others have broad flat stigmas which curl apart. When touched by a bee's 

 head in passing in, the stigmas close in a few seconds, and coyer the surface 

 which is sensitive to pollen. While taking the honey, the bees are dusted with 

 pollen which is just in the right place to be left on the stigma when entering 

 the next flower. In these flowers, self-fertilization is impossible unless in rare 

 and exceptional cases. Flowers of Dutchman' s-pipe, some arums, and lady's- 

 slippers, entrap and hold as prisoners different kind of small insects which 

 enter them. They are not prisons like Libby or Andersonville in miniature, 

 for they treat their prisoners well, with good shelter and an abundant of food 

 and drink of the best that nature affords. The flowers of our common flax are 

 absolutely sterile when close fertilized by the pollen which is ready in abun- 

 dance, and often falls upon the stigma of the same flower. Bees cause the 

 flowers to get seeds by crossing with the proper pollen. Our crop of flax seed, 

 then is benefited in yield, and in some cases entirely dependent on the aid of 

 the little busy bee. Our common garden beans are self-fertilizing to a certain 

 extent, but the crop is more than doubled by the aid of bees. 



Most or all plants are better for a cross. This is not always so apparent at 

 first, as it is after several generations of plants raised from self -fertilized flow- 

 ers. In such cases, a cross adds increased vigor and fruitfulness. Many, very 

 many flowers you see, are as plainly intended for cross fertilization as the beak 



