i.S6 Elementary Botany 



Each of these orders contains numerous plants, which are 

 arranged in genera and species. A genus is an assemblage of 

 plants which resemble one another more closely in general 

 structure and appearance than they do other species of plants. 

 Thus, if we examine a Sweet Violet, a Dog-violet, and a Pansy, 

 we find that although they differ in many minor points of 

 detail, yet there is a great resemblance between them which 

 causes them all three to be grouped under the genus Viola. 

 By a species we mean an assemblage of individuals which 

 whilst possessing the characteristics of the genus, possess in 

 addition distinctive characters which separate them from the 

 allied plants of the same genus. Thus the points in which the 

 Sweet Violet, Dog-violet, and Pansy agree would be their 

 generic characters ; whilst the points in which they differ are 

 their specific characters. When the seed of a plant is grown it 

 always reproduces the same species as the parent. In giving 

 the riame of a plant we place the generic name first, followed 

 by the specific name. Thus the Sweet Violet is Viola odorata, 

 the Dog-violet Viola- cani-na, and the Pansy Viola tricolor. 



Sometimes the pollen of one species will fertilise the ovule of 

 a closely allied species, and a plant is thus obtained which com- 

 bines the properties of both. Such a plant is said to be a hybrid. 



We will now give a detailed account of the various orders, 

 in each case mentioning a typical plant that should be carefully 

 examined and compared with the description of the order. 



DICOTYLEDONS. 



THALAMIFLORAL ORDERS. 



RANUNCULACEvE. 



Plant for examination, Buttercup (there are several species 

 any of them will answer for the purpose). 



Note that the plant is an herb (the Clematis is a shrubby 

 climber ; otherwise the plants of the order are all herbs). If 

 you have a specimen with leaves on the stem, they are arranged 

 in an alternate manner (in the Clematis they are opposite) 

 Often the bases of the leaves sheath around the stem. ■ Examine 

 the flower, making a vertical section through one (fig. 165), 



