FLOWERS OF THE TREES. 



The trees are usually in flower before 

 the leaves come, and so secure for the 

 blossoms the full benefit of the sunshine. 

 Except in the fruit trees, the flowers of 

 the trees are, for the most part, incon- 

 spicuous. They are of a green or 

 greenish color, with little or no odor. 

 Color and odor are associated with insect 

 pollination, and the trees that make no 

 display of flowers are dependent on the 

 wind. 



Wind pollination is- very extravagant. 

 Only one grain of pollen is required to 

 fertilize one ovule ; yet in the case of the 

 pine the ratio is seven thousand grains of 

 pollen to one ovule. In the South, in 

 the late spring, when the pine trees are 

 in bloom, the light pollen dust is blown 

 in clouds for miles about, giving rise to 

 various newspaper allusions to sulphur 

 showers ! 



Nature's first aim is towards success 

 in her purpose ; so that she is willing that 

 myriads of forms should be lost so that 

 this success may be attained. But her 

 second aim is towards economy, so we 

 find her working out plans to reduce the 

 amount of material to be manufactured 

 and to secure the surest agent for its 

 distribution. 



Insects carry pollen on their wings or 

 heads, from flower to flower, wasting 

 little and placing it accurately where it 

 will perform its work. The flowers that 

 are so served by the insects must offer 

 to them certain compensations for the 

 service. So we find many trees, notably 

 the fruit trees, with blossoms rich in color 

 and odor, ready to attract the small 

 visitors. There is usually, too, a gen- 

 erous amount of nectar stored in the 

 heart of the flower, cleverly put there so 

 that in securing it the insect must brush 

 off all of the pollen it has brought from 

 a neighboring flower. 



In the change of the agent for the 

 carrying of the pollen, the pollen itself 

 has altered its character. When it was 

 produced in large quantities and blown 

 about by the wind it was dr\^ and fluffy. 

 But when insects were employed the 

 pollen became sticky, so as to adhere the 



better to their bodies and lessen the 

 chance of waste. 



Trees belong to either one or the other 

 of the two great groups into which 

 flowering plants are divided: Gymno- 

 sperms or Angiosperms. Gymnosperms 

 are lower in the scale of development 

 than the Angiosperms because the organs 

 of the flower are less specialized. In- 

 deed, the flower of the Gymnosperms can 

 hardly be recognized as such by the 

 ordinary observer; but since it consists 

 of the essential organs of the flower, the 

 stamens and pistils, or at best the vital 

 parts of these organs, it is classed as a 

 flower. 



The pine is a characteristic member of 

 the Gymnosperms. Its flowers are 

 monoecious ; that is, the pistillate flowers 

 and the staminate flowers are separate but 

 borne on the same tree. The pistillate 

 flowers are arranged in a scaly catkin, 

 which afterwards becomes a cone. Each 

 bract bears at its base a pair of ovules 

 side by side, all that there is of the pistil- 

 late flower. These ovules are not 

 enclosed in an ovary — ^the main char- 

 acteristic of Gymnosperms. The pollen 

 blown from the staminate flowers enters 

 the ovule directly through a minute 

 orifice, and fertilization is complete. 

 Gymnosperms are pollinated altogether 

 by the wind. 



The Angiosperms bear flowers that 

 enclose their seeds in a special sac, the 

 ovary. The flowers are either dioecious, 

 as the willow, with staminate catkins on 

 one tree and the pistillate on another; 

 or monoecious, as the oak, with both 

 kinds of flowers on one tree. Except in 

 the fruit trees, there are usually no petals 

 or sepals, but the flowers consist merely 

 of groups of stamens or pistils. The 

 pollen is carried by the wind or by an 

 insect from the staminate flower to the 

 pistillate, where it finally finds its way 

 to the ovary. If the style is present, the 

 grain drops on the stigma, where it is 

 moistened and develops shortly into a 

 tube. This tube pushes its way through 

 the style and so reaches the ovule. The 

 process varies in time, sometimes requir- 

 ing several days for completion. 



Mary Lee Van Hook. 



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