THE PLANT GROUPS 149 



is the structure of these cells and how would 

 they work in opening and closing the anther sacs ? 

 (4) Microspores. Xote the structure of the microspores 

 or pollen grains. What is the nature of the outer 

 wall, or extine ? Outline one half of your section 

 and detail the cell structure of wall cells and 

 microspores on a part of the section. Label 

 correctly. 

 d. Pistil and fruit. 



(1) Study the pistil, noting particularly the nature and 



extent of the ovary, style, and stigmatic surface. 

 Is each pistil simple or compound ? Observe the 

 megasporangium, or ovule, best seen in mature 

 fruiting pistils. Compare* the megasporophyll 

 and sporangium with that of Caltha in the text. 



(2) Drawing. Draw the pistil so as to show the stigmatic 



surface magnified and the relation of megasporo- 

 phyll and megasporangium. 



(3) Fruit. Make a drawing to illustrate the nature and 



parts of the fruit. 



CAP SELL A (SHEPHERD'S PURSE) 



Study the flower and inflorescence of the shepherd's purse as 

 outlined above under Reproduction, 1, a (see Fig. 251, p. 400, 

 of text). Make the following special study of pistil, megaspo- 

 rangium, megaspore, and embryo sporophyte. Consult the text 

 discussion of Capsella (p. 345 of text, and Fig. 203). 

 1. Pistil. 



a. Study young and mature pistils on the inflorescence 

 of Capsella and determine the relation of stigma, 

 style (if present), and ovary. Is the ovary simple 

 or compound ? How many placentae are there and 



