ON VFGETATIOV. 731 



from the number of pistils, or little columns immediatefy connected Math the 

 seed vessel; and denominated nionogyaia, digynia, and so foith, as far as po- 

 lygynia. These classes dift'er little in general with respect to their natural habits, 

 except the twelfth, icosandria, which is characterized by the attachment of the 

 filaments to the green cup, surrounding the flower, and which comprehends 

 the most common fruit trees: this class has, however, been incorporated by 

 some later botanists M'ith the next. In the third class we find most of the 

 natural order of grasses ; the fifth, pentandria, is by far the most numerous 

 of any: the sixth contains the lilies, and many other bulbous plants. The 

 14th class, didynamia, is known by tvv^o longer and two shorter filaments; 

 it is perfectly natural, and comprehends flowers similar in their structure to 

 the foxglove and the deadnettle. The 15th also, tetradynaniia, is a class 

 of plants strongly characterized even by chemical properties; two of the fila- 

 ments are here shorter than the other four: cresses, radishes, and many other 

 acrid and ammoniacal vegetables belong to this class, as well as the turnip 

 and cabbage, which, when cultivated, become mild and nutritious. The class 

 monadelphia contains a few plants similar to the mallow; they are known by 

 the union of the filaments at their bases into a cylinder: those of the next 

 class have generally nine united, and one separate, whence the class is named, 

 diadelphia; it contains the papilionaceous flowers, somewhat resembling a 

 butterfly in their form, like the pea, and other leguminous plants, the broom, 

 the furze, and the acacia. The 18th class, polyadelphia, has the filaments of 

 its flowers united into several masses or bundles, as the hypericum or tutsan. 

 The next class is perfectly natural, and contains the composite flowers, which 

 have a peculiar union of the summits of the filaments; it is named syngenesiai 

 sunflowers, daisies, and artichokes, are familiar examples of the plants of this 

 class. The 20th class, gynandria, though it contains the natural family pf 

 the orchides, has been omitted by some late botanists; here the filaments arc 

 fixed on the pistil ; or more properly, in the arums, within the pistils. The 

 three following classes, monoecia, dioecia, and polygamia, difter from the 

 rest in having some flowers with filaments or chives, and some with pistils 

 only, either on the same plant, or on different plants, or mixed with flowers of 

 the mare common construction. Most of the forest trees belong to these 

 classes, but the distinctions which separate them from other classes are not 

 always very uniformly preserved, and, for this reason, many later botanists 

 have disused them. The plants of the last class, cryptogamia, are exceeilingly 

 numerous; the families of ferns, mosses, algae, or membranous weeds, and 



