UNDER-GROUND SEEDS 13 



There is considerable cross-pollination in nearly all flowers. 

 In many cases, as orchard fruits already mentioned, the pollen car- 

 ried from one plant to another may be more likely to grow well. 



How Pollen Is Carried. — There are two general methods by 

 which pollen may be carried from one flower to another, whether 

 these be on the same plant or on different plants, viz., (1) by insects 

 (Fig. 7) and (2) by wind. Of course pollen may be carried by 

 hand on a soft brush. This is often done in greenhouses, and where 

 crossing of two kinds is desired. 



Pollination by Insects. — When insects, such as honey bees, are 

 in searcb of nectar or pollen itself, they visit many flowers of the 

 same kind and carry pollen from one to another. The pollen on 

 their bodies and appendages is rubbed against the stigma of the 

 pistil and the cross-pollination is complete. 



Flowers which insects like to visit have (1) sticky or heavy pol- 

 len, (2) are showy by having colored sepals or petals, or (3) bear 

 nectar, and (4) are often fragrant. Usually all four of these 

 characters are found in flowers pollinated by insects. Common 

 fruit blossoms are nearly all examples of this type of flowers. 



Pollination by Wind. — When the pollen is to be carried by the 

 wind it becomes dry and powdery and is comparatively light. The 

 flowers have no need for being showy and no nectar or fragrance 

 is found. Corn, grasses, some small grains, plantain, and many 

 weeds are examples of flowers pollinated by wind. 



Under-ground Pollination. — There are a few plants, as the 

 violet, which bear two kinds of perfect flowers. The showy flowers 

 which we commonly see in the spring, and others borne under the 

 ground later in the season. These are small, closed buds and pol- 

 lination takes place within them. Later the seed pods of the violet 

 project above ground in order to spread the seed, (Fig. 8). Other 

 plants which bear this type of hidden flowers are the hog-peanut, 

 dalibarda and fringed wintergreen. Such flowers are called cleisto- 

 gamous, meaning hidden-union. In such cases nature enforces self- 

 pollination. 



Under-ground Seeds. — Most seeds are borne in the air, but 

 the peanut is a common exception to this rule. In this plant the 

 showy flowers are staminate and are borne well up on the stems. 

 Nearer the ground there are small pistillate flowers. After the 

 pollen growth has fertilized these small flowers, the flower stem 

 elongates and they are thrust down into the ground, where the 

 pods and seeds will mature. 



