8 MANUAL OP BOTANY 



history of a plant or group is required. Those characters, again, 

 which refer to a species are called specific, and are taken gene- 

 rally from all the organs and parts of the plant, and relate 

 chiefly to their form, shape, surface, division, colour, dimension, 

 and duration ; or, in other words, to characters of a superficial 

 nature, and without reference to their internal structure. The 

 characters of a genus are called generic, and are taken from the 

 organs of reproduction. The characters of an order are termed 

 ordinal, and are derived from the general structure of the plants 

 in such groups, more especially of the organs of reproduction ; 

 while the characters of a class, &c., as already mentioned, are 

 derived from certain important structural pecuharities which 

 the plants of such divisions exhibit. 



2. NoMENCLATTjRE. — It is the object of nomenclature to lay 

 down rules for naming the various kinds of plants and the dif- 

 ferent groups into which they are arranged in our systems of 

 classification ; in the same manner as it is the object of termi- 

 nology to find names for the different organs of plants, and the 

 modifications which those organs present. 



a. Species. — The names of the species are variously derived. 

 Thus the species of the genus Viola, as shown by Gray in the 

 following paragraphs, exhibit the origin of many such names. 

 ' Specific names sometimes distinguish the country which a 

 plant inhabits: for example, Viola canadensis, the Canadian 

 Violet ; or the station where it naturally grows, as Viola 

 palustris, which is found in swamps, and Viola arvensis, in 

 fields ; or they express some obvious character of the species, 

 as Viola rostraia, where the corolla bears a remarkably long 

 spur, Viola tricolor, which has tri-coloured flowers, Viola ro- 

 tundifolia, with rounded leaves, Viola lanceolata, with lanceolate 

 leaves, FioZa ^edato, with pedately -parted leaves, Viola primu- 

 Imfolia, where the leaves are compared to those of a Primrose, 

 Viola asarifolia, where they are hkened to those of Asarum, 

 Viola pubescens, which is hairy throughout, &c. Frequently 

 the species bears the name of its discoverer or describer, as 

 Viola Mulilenhergii, Viola Nuttallii, &c. 



Specific names are written after the generic, as indicated 

 above in the different species of the genus Viola, and these 

 together constitute the proper appellation of a plant, in the 

 same way as the surnames and christian names designate the 

 members of a family. The specific names should also in all 

 cases be adjectives or substantives used adjectively ; in the 

 former Case they should agree in gender and case with the name 



