234 Introduction to Botany. 



cross section of the ovary, showing the attachment of the 

 ovules. (It is a good plan to select a somewhat mature 

 fruit for this purpose.) What are the relative positions of 

 anthers and stigmas ? Are stigmas and anthers mature at 

 the same time ? Is self pollination liable to take place ? 

 Find the nectaries. Is the flower fragrant ? When insects 

 visit these flowers, would they be likely to cause self or 

 cross pollination ? Make a drawing showing how the 

 capsules break open, and how the seeds become scattered. 

 This plant has become naturalized from Europe. It 

 occurs in nearly all parts of the world and shows a great 

 aptitude in taking possession of waste places. It has a 

 great advantage over most other herbaceous plants in 

 being able to withstand low temperatures and to send 

 forth its leaves and flowers in the first warm days of late 

 winter or early spring. (See on page 311 an account of 

 Cochlearia belonging to the same family.) Watch for it at 

 such times and note how much it is in advance of other 

 plants. Now note down all of the points in its structure 

 and habits which help to make it a successful competitor 

 with most other plants in all parts of the world. (Read 

 the chapter on Plants of Different Regions.) Compare 

 other genera in this family with Capsella. 



Prunus chicasa (or other species). 



Study the trees in their native habitat at the time of 

 blooming. What is the character of the inflorescence ? 

 At what stage of development are the leaves when the 

 tree is in blossom ? Tell the different means by which 

 the flowers are made conspicuous. Draw a flower from 

 the point of view which best shows the form and relative 

 positions of all the parts. What is the position of the 

 anthers with reference to the stigmas ? Do the anthers 



