CLASSIFICATION OF PLANTS. 



103 



bestowed upon the genus. The popular term Lily also 

 comprehends many species, whose relationship is obvious 

 to all. These may be taken as illustrations of the 

 groups of species which constitute genera, and of the 

 principles which control this arrangement. The number 

 of species in a genus varies from several hundred in cer- 

 tain large genera, to a very few. One species, even, 

 frequently forms as characteristic a genus, and one as 

 obviously distinct as any of those consisting of many. 



Sometimes in large genera, or in those where all the 

 species are not very closely related to each other, those 

 species which have the greatest af&nity for each other, 

 are placed by themselves in sections ; and when these 

 sections are quite distinct, and there arc no intermediate 

 species connecting them, they are called Sub-genera. 



Allied genera also, by an extension of the same prin- 

 ciple, are grouped into Orders. These, then, consist of 

 genera, which, to a great extent, or in many of their 

 most important characters, follow the same general type, 

 or model, and which are more nearly allied to each other 

 than to any other genera. These genera almost always 

 bear such a general resemblance to each other, that their 

 relationship is evident to all who are accustomed to use 

 their faculties of observation. In many cases the af- 

 finity is so strong as to be recognized by all. Such 

 orders are the Umbelliferous plants, including the Car- 

 rot and Parsnip tribe, and the Pine family, where the 

 affinities of all its different members, in their various 

 forms of Pines, Firs, Spruces, and Cedars, are univer- 

 sally recognized. In almost all cases, however, the 

 practical eye of a Botanist is able at once to detect the 

 true character of a plant, and to refer it to its proper 

 order at the first glance. Orders, like genera, may con- 

 sist of many members, or few. A single genus, even, 

 sometimes forms an order by itself. 



In very large orders, or those where the diiferent mem- 

 bers have not a very strong affinity for each other, the 

 order is broken up into sections, which are called Tribes. 

 These also are sometimes divided again into Sub-tribes. 

 When, however, these distinctions are important, and 

 are nearly sufficient to constitute orders, the divisions are 

 called Sub-orders. 



By a still further extension of the same principles, 

 orders are grouped into Classes ; and these generaliza- 

 tions might be carried even further, if necessary. Classes 

 are also divided into Sub-classes, under the same con- 

 ditions as before. 



The distinctions between the classes of the Natural 

 System are so obvious, and so important, the principles 

 upon which they are founded are so simple, and the 



classes themselves are so few, that it is easy to give a 

 sufficiently clear and precise explanation of them in a 

 very small space, so that the learner may comprehend 

 them, and thus soon be able practically to distinguish 

 between them, and refer any of the plants of his acquaint- 

 ance to their proper position. But the distinctions upon 

 which orders are founded are so numerous, and so com- 

 plex, requiring the consideration of so many particulars 

 and circumstances, that I reserve them for future con- 

 sideration, so as to be able to give a general and compre- 

 hensive review of the Vegetable Kingdom in the shortest 

 possible compass. The same remark applies still more 

 directly to the genera and species, which in almost any 

 possible district are so numerous, that they are always 

 reserved for a separate department called a Flora. Ac- 

 cordingly I restrict myself here to a view of the principal 

 divisions merely of the Natural System. 



The entire Vegetable Kingdom is divided into two 

 great series, the Phgenogamous, or Flowering plants, and 

 the Cryptogamous, or Flowerless plants. The leading 

 distinctions have already been explained ; but it may be 

 well to recapitulate them. The first series is distin- 

 guished by the possession of ^proper flowers, i. e. those 

 with stamens, or pistils, or both. They produce ovules, 

 or undeveloped seeds, which, when fertilized by the pol- 

 len, become proper seeds, possessing within themselves 

 an embryo or undeveloped plant, destined by germination 

 to become the future vegetable. 



In Cryptogamous plants, on the contrary, we find 

 neither proper stamens nor pistils, nor, in fact, any 

 organs, so far as we can discover, performing their offices. 

 They produce no ovules, which fertilized by pollen be- 

 come seeds, containing the future plants in embryo ; but 

 they reproduce themselves by minute reproductive cells 

 called spores, which, by cell-growth, develope the new 

 plant. This last series are all herbaceous in our cli- 

 mate, and include the Scouring Bushes, Club-mosses, 

 Ferns, Mosses, Liverworts, Lichens, Fungi, Seaweeds, 

 and a few unimportant aquatic plants ; whUe the Phteno- 

 gamous plants, a very much larger list, include all 

 others. 



Phjenogamous plants are again divided into the two 

 classes of Exogens and Endogens. The principal dis- 

 tinctions upon which this classification is founded have 

 already been explained, but, as before, for the sake of 

 completeness, I will recapitulate briefly. They are dis- 

 tinguished mainly by differences in the mode of growth. 

 These differences are most clearly defined in the woody 

 stems of the two classes. Exogenous trees possess a 

 stem readily distinguishfible into bark, wood, and pith, 



