304 ] The Fascination of Flowers 



upper petals are erect, suggesting colorful display signs. They are 

 marked with lines that point toward the opening of the nectar 

 tubes. The lower petals stand out to form a landing platform for 

 visiting insects. 



Despite this, the flower is not actually designed for hospitality; 

 it can accommodate only big insects such as sizable bees or butter- 

 flies for its pollination work, and it is able to thwart smaller, use- 

 less creatures that might creep into its treasure house of nectar. 

 Each of the lower "landing" petals narrows to a fine strip at its 

 inner end, making it in effect a footbridge to the nectar tube. 

 These bridges are covered with projecting fringes and numerous 

 little spikes that prove an effective barrier to any small creeping 

 visitors. 



Mechanized Pollination: When a nasturtium first opens, its several 

 stamens are all bent downward. But when the pollen-containing 

 anthers located at the end of each slender stalk of a stamen 

 are ready to function, the stalk lifts up so that it is directly 

 in the path of the nectar store. When a bee or butterfly, or oc- 

 casionally a hummingbird, touches the stamens, it is sometimes 

 bombarded with pollen. Equally remarkable is the action of the 

 anther: No sooner has it discharged its pollen than it shrivels, 

 making way for a new anther. 



While all this is going on, the flower's three-lobed stigma lies 

 quietly below and behind the anthers. (The stigma is located 

 on the prolongation of the ovary known as the style.) But, once 

 all the pollen has been shed, the stigma rises up and opens. Now 

 the stigma operates like a three-pronged fork, and as more insects 

 come in quest of nectar, it rakes pollen from them. Thus the 

 ovary is fertilized and the seeds are ready to develop. 



PETUNIAS AND THEIR INTERNATIONAL BACKGROUND 



Profusely blooming petunias are so much a part of our 

 American garden scene that it comes as a surprise to us to learn 

 that they have an international background. They are the result 

 of a cross between two species of plants from different parts of 

 South America. The first of these, with long-tubed white flowers, 

 was brought to Europe a little more than a hundred years ago. 



