Reproduction 377 



Under exceptional conditions fruiting of the oak or 

 apple may occur in the nursery stock. On the other 

 hand annuals may be induced to grow for a period of 

 years without flowering. With a careful selection of 

 conditions, and by employing vegetative propagation when 

 necessary, Klebs was able to induce continuous growth 

 and fruiting in Parietaria officinalis. Uninterrupted 

 growth, without flowering, was obtained with Fragaria 

 lucida, Glechoma hederacea, Rumex acetosa, and other 

 species, - - plants which normally produce blossoms in 

 summer. These facts suffice to suggest the complexity 

 of the relations, and the importance of determining the 

 releasing stimuli, with respect to vegetation and fruiting. 



LABORATORY WORK 



The flower. - - Review or study the morphology of the flower, 

 giving attention to monoecious and dioecious plants as well as to 

 those with perfect flowers. 



Study more completely the floral mechanism in two or three 

 representatives of some one order, such as the Liliaceae or Legu- 

 minosae. [Consult Church or some other convenient text.] 



Anther and pollen. - - Cut crosswise the large anthers of some 

 plant, such as lily or tomato, press out the pollen-forming areas, 

 and note the changes in the character of the contents of the anther 

 (pollen) sacs, or microsporangia as maturity proceeds. 



Study and describe the pollen from plants in at least two 

 different orders, mounting it both dry and in water. 



Set uj germination experiments with pollen from several plants 

 which produce tubes readily (within a few hours) in water or 

 sugar solution. Germinating well in 3 per cent sugar solution 

 there are among the numerous monocotyledons which might be 

 used, several species of lily, also orchids, tulip, and Narcissus ; 

 while cucumber, buttercups, willows, and Erica are among favor- 

 able dicotyledons. 



