TYPE STUDIES, SEED PLANTS 179 



2. Wiiat plants (if any) are common to two or more for- 

 mations. 



3. Some of the causes of the boundaries between formations, 

 and whether these boundaries are fixed or shifting. 



B. Make a sketch map of the series of zones on the same gen- 

 eral plan as that of Fig. 366 in Principles, and if possible 

 secure one or more photographs of the series, with a large 

 numbered placard set up in a prominent position in each zone. 



STUDY OF TYPES OF SEED PLANTS* 



161. Family Pinacese.i 



162. Family Liliaceae. Any obtainable genus may be used to represent 

 the family. Lilies, tulips, dogtooth violets {Erythronium), Scilla sibirica, or 

 Roman hyacinths answer excellently. Since it is to be had of florists during 

 the winter months and in gardens for a long time in spring, the lily of the 

 valley (Convallaria) is here taken as a type. As an alternative the study of 

 Erythronium is also outlined. 



Convallaria majalis, L. 



A. Sketch the entire plant. 



B. Does the underground portion all belong to the root system ? Give 

 reasons for conclusion. Is it highly specialized for storage of reserve 

 material ? 



1. Test a piece of it (collected in winter) for starch. Sec. 12. 



2. Cut a cross section of the most vigorous portion, examine with m.p. , 

 and decide which of the types of stem studied in Sees. 25, 26, it 

 most resembles. 



3. In early spring note the manner in which the plant emerges from 

 the ground. 



C. In the portion above ground note first the scale leaves, and, higher up, 

 the foliage leaves. Label these in your sketch. 



1. Are both leaf surfaces equally or unequally exposed to the light ? 

 Hold a leaf up to the light and study its venation. Describe it. 



* To THE Instructor : As these studies consume much time, it may be found 

 desirable to select only a few of them. One of the longer ones, like Sec. 165 or 

 Sec. 167, thoroughly worked out, is worth more than the whole series hurriedly 

 done. 



1 A detailed study of the pine may be found in Sec. 138. It may, if necessary, 

 be simplified to make it homologous with those studies of families of angio- 

 sperms which here follow by omitting some of the histological work and the 

 larger part of the details about the process of reproduction In gymnosperms. 



