EXERCISE 50 



PREVENTION OF LOSS OF POLLEN 

 Materials. Flowers, in the field or garden. 



Directions for work. 1. Protection from rain. Pollen grains 

 which are placed in water soon absorb enough water to cause 

 them to burst. Rain may either destroy the pollen or wash it 

 out of the flower. Some plants, but not all, have flowers so 

 constructed that the pollen is not exposed to rain, or the flowers 

 may close in rainy or cloudy weather, 



List the kinds studied, and in column ^ note the sort of pro- 

 tection from rain which you find, or the absence of protection. 



2. Protection from injurious insects. Many flowers are equipped 

 with devices which exclude such insects as might feed upon the 

 pollen or nectar but are not likely to cross-pollinate the flower. 

 Ants are the most important insects in this class. 



The most common protective characters are hairs on the stem 

 or flower stalk, sticky zones on the stems or flowers, narrow 

 corolla tubes, narrow-throated corollas, and inclosure of the 

 stamens by an almost closed corolla. Examine the flowers you 

 have at hand and note the protective devices, if any, in column B. 



NAME 



Reference 



LUBBOCK. Flowers, Fruits, and Leaves, chap. ii. The Macmillan 

 Company. 



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