xiv INTRODUCTION TO BRITISH BOTANY 



Sub-class IV. MONOCHLAMYDE^.* 



Class II. MONOCOTYLEDONS. 

 Perianth single, or none. 



Seeds with a single cotyledon. It is subdivided into two Sub- 

 classes, Petaloide.e and Glumace.e. 



Sub-class I. Petaloide^. 

 Flowers with petals. 



Sub-class II. GLUMACE.E. 



Flowers formed of chaffy scales, or glumes. This Sub-class con- 

 tains the Grasses and Sedges. 



Class III. ACOTYLEDONS. 



Flowerless plants. Here arc placed the Ecrns, Mosses, Liver- 

 worts, Lichens, Sea-weeds, and Fungi, not included in the present 

 work. 



Each of the Natural Orders, or Tribes, alluded to above, consists 

 of a number of plants which are more or less like one another in 

 various respects, especially in the organs of fructificalion. The 

 plants comprised in each Tribe are again distributed into genera, 

 or families, each genus including all plants which resemble one 

 another yet more closely in the essential characters of fructifica- 

 tion. A species, or ki?ui, is an assemblage of individual plants 

 agreeing with each other in all essential points ; and individuals 

 which differ one from another in minor points, such as an irregular 

 formation of leaves or mode of growth, unusual colour of flowers, 

 extraordinary number of petals, etc., are termed varieties. These 

 words are frequently used loosely in common conversation, but 

 the habit cannot be too carefully avoided in botanical descriptions, 

 as calculated to produce great confusion. Throughout these pages 

 they will be employed exclusively with the meanings above assigned, 

 which wiU be rendered clearer by the following examples : The 

 wild sweet-scented Violet is called by botanists Viola odorata ; the 

 former name, Viola, indicating that it belongs to the genus so called, 

 and being, therefore, termed its generic name. Besides the scented 

 Violet, we have in England the Dog- Violet, the Marsh- Violet, the 

 Pansy, and several others, all belongmg to the same genus, and, 

 therefore, described under the name Viola. But the Dog-Violet 

 difters from the Sweet-scented in having acute sepals, and leafy 

 stems, whereas the latter has blunt sepals, and the leaves sprin^^ 



* From the Greek nionos, one, and clilamys, a mantle or covering- the 

 plants of this Snb-cla5s never having botli calyx and corolla. ° ' 



