APPENDIX. 313 



The two orders of the 15th class are distinguished by the 

 form of the fruit ; the first, called siliculosa, has broad short 

 pods, as in pepper-grass or wild-cress ; and the second, called 

 siliquosa, is known by its long pods, as in wild radish and 

 common mustard. The orders of the 16th, 17th, and 18th 

 classes, are characterized by the number of stamens in each 

 flower, and the names of some of the classes, therefore, are 

 used to distinguish them, as Triandria, Decandria, Polyan- 

 dria, &c. The 19th class has five orders, 1st, cequalis, all 

 the florets with stamens and pistils, and all fertile ; as dan- 

 delion, burdock, and cotton thistle : 2d, superflua, florets of 

 the disk, or surface with stamens and pistils, those of the 

 margin with pistils only, all fertile, as common life-everlast- 

 ing, white weed, and elecampane : 3d, frustanea, florets of 

 the centre with stamens and pistils, fertile ; those of the 

 margin with pistils only, barren, as the sunflower : 4th, ne- 

 cessaria, florets of the centre with stamens and pistils, bar- 

 ren ; those of the margin with pistils only, fertile, as what is 

 called high water shrub, growing about the borders of salt 

 marshes : 5th, segregata, comprehends such flowers as have 

 tubular florets, all perfect, each floret having its own sepa- 

 rate calyx, in addition to the general calyx, which includes 

 all the florets, as the globe-thistle. The orders of the 20th, 

 21st, and 22d classes are distinguished by the number of sfa- 

 mens. The 23d class has three orders, 1 st, monmcia, barren, 

 fertile, and perfect flowers, found in one plant, as poke root, 

 or American hellebore : 2d, dicEcia, barren, fertile, and per- 

 fect flowers on different plants, as ginseng, swamp maple, rock 

 maple, and white ash : 3d, tricucia, the same on three sepa- 

 rate plants ; of this, the figtree is supposed to be a solitary, 

 though doubtful example. The 24th class has 5 orders, 

 Filices, Ferns ; Musci, Mosses; Hepaticce, Liverwort; AlgcB, 

 Flags ; Fungi, Mushrooms. The term. Algae, was original- 

 ly applied to marine plants, as sea- weeds, but it has been, 

 employed in a more extensive sense, and, among others, em- 

 braces the Lichens which cling to rocks. Note. The 21st, 

 22d, and 23d classes have been abolished by some writers. 



The instructer should read and explain to his pupils the 

 names of the classes and orders, and point out the circum- 

 stances on which their distinctions are founded, by the help 

 .of engravings, or real specimens. 



It may be proper to give an example of the division of 

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