46 PHYSIOLOGICAL PROCESSES IN PLANTS 



this cluster yellow or white flowers? Into how many parts is the calyx 

 divided ? The corolla ? Is the corolla perfectly regular ? Notice the 

 live stamens ; is there anything peculiar about the filaments ? Are they 

 all of the same length ? In spite of the fact that the flower is called 

 moth mullein, it is not pollinated to any extent by moths. Bees and 

 flies are the chief pollen bearers. Bees which alight on this flower do 

 so for the purpose of collecting pollen. . This they usually gather from 

 the short stamens while they cling to the longer ones. As the bee lights 

 on another flower, the pollen on the under side of the body is transferred 

 to the stigma of this flower. 



Draw the flower from above, twice natural size. 



Jewel Weed (Impatiens 6(#ora). One of the most prevalent of all 

 our brookside flowers is the jewel weed. It well deserves its name, a 

 pendent flaming jewel of orange. 



The flower is very irregular in shape. Are the flowers single or in 

 clusters ? The sepals as well as the petals are colored. The former are 

 three in number, one of which is saclike in shape and contracted at one 

 end into a spur. The petals are also three in number. Open the flower. 

 Notice how short the filaments of the five stamens are. Make a note 

 of their position with relation to the pistil. Would self-pollination be 

 possible in this flower ? 



If it is possible to study jewel weed out of doors in its native habitat, 

 it will be found that humming birds are the visitors which seem best 

 adapted to cross-pollinate the flower. A careful series of observations 

 by some girl or boy upon the cross-pollination of this flower might add 

 much to our knowledge regarding it. 



Jewel weed has the habit of producing (usually in the fall) incon- 

 spicuous flowers which never open but which produce seeds capable of 

 germination and growth. Such flowers are said to be cleistogamous. In 

 England, where the plant has been introduced, it is found to produce 

 more cleistogamous flowers than showy ones, and the showy ones do not 

 produce seed. There are no humming birds in England, and without 

 this means of pollination, the cleistogamous form prevails. Make a 

 front view drawing of the flower of jewel weed twice natural size. 



d. Other Agents 



Method. Refer to or study as many other flowers as possible. Study 

 the Figures of other types, using charts or texts. 



Observations. 1 . Seek for any peculiarities of structure that would 

 lead you to think that they are for purposes of pollination. If possible, 

 especially study the structure of the sage blossom, pea or bean, and 

 violet. 



2. Find out how pollination is accomplished in the corn plant and the 

 willow. 



3. Find out the same thing for pines. Eel grass. Primrose. Jack 

 in the pulpit. Iris. Orchids. 



