188 STUDY OF COMMON PLANTS. 



V. The single pistillate flower is far more conspicuous 

 than the staminate ones. As the ovary develops it pro- 

 trudes beyond the involucre, so that the entire flower is 

 easily studied. Observe 



1. The form of the ovary. 



2. The number of styles and stigmas. 



3. The number of cells in the ovary, as seen in cross- 



section, and the number and position of the 

 ovules. 



VI. With a number of entire plants review all that we 

 have learned about the species. See that all the facts are 

 clearly in mind, and that you are able to designate each 

 part by its proper name. Do you consider the plant well 

 adapted to* survive in the struggle for existence ? If so, 

 show how. 



RELATIONSHIP. 



With the species already studied compare other mem- 

 bers of the genus such as Euphorbia corollata, L., E. 

 marginata, Pursh, E. maculata, L., and one or more repre- 

 sentatives of other genera, as, for example, Acalypha 

 Virginica, L., and the cultivated castor-oil plant, Ricinus 

 communis, L. (The seeds of the latter are of large size, 

 and are more easily studied than those of the spurge.) 



Having compared as many species as practicable, see 

 how far the characters you have found to be common 

 to all agree with the family characters as given in the 

 manuals. 



Euphorbia Cyparissias is a familiar representative of a 

 large and peculiar family of plants. It is found in patches 

 by roadsides and old dwellings where it has escaped from 

 cultivation. Its copious milky juice, narrow leaves, and 

 tufted habit have given it the common name of " milk- 



