258 COLLEGE BOTANY 



into classes. Although these are the most important groups, 

 other divisions are sometimes made for convenience. Although 

 the species may be considered the final group, yet we find many 

 variations which' sometimes necessitate smaller groups known 

 as varieties. This is especially true of cultivated plants, and 

 the commercial varieties of some species are numerous. 



The specific name usually indicates some character of the 

 plant to which it is attached, i.e., vulgaris = common, nigra = 

 black and rubra = red. The Latin generic names are always 

 written in the nominative case. The family names usually end 

 in acece. The order names always end in 

 ales. The class names usually end in inece 

 or ece. The division names end in phyla, 

 or phyte. 



The plant kingdom as a whole may be 

 divided into four large groups or divisions 

 as follows : 



I. Thallophyta, which includes the 

 algae and fungi (page 260). 



II. Bryophyta, which includes the 

 liverworts and mosses (page 289). 



PIG. ii7.-Linnu8. jjj pt er ido p hyta,,. which includes the 



ferns and related plants (page 297). 



IV. tSpermatophyta, which includes all seed-producing 

 plants (page 303). 



The Spermatophyta are divided into two groups, the Gymno- 

 spermce (such as the pines, spruce, etc.) ; which produce seeds 

 but no flowers and are mostly evergreens, and the Angio- 

 spermce, which include the higher seed-bearing plants or time 

 flowering plants. 



The Angiospermce are divided into Monocotyledons, in 

 which the embryo has but one cotyledon or primary leaf, and the 

 Dicotyledons, in which the embryo has two cotyledons (see page 

 304). Since the seeds of many plants are so very small, it is 

 frequently desirable to use other characters. With some few 



