CLASSES, ORDERS AND SPECIES. 97 



tansey. 2d, those with rays, as the aster genus, golden-rod. 3d, 

 order Frustranea, disk florets perfect, as coreopsis, helianthus, blessed 

 thistle. 4th order, Necessaria, rays fertile, disk florets barren, as the 

 marygold. 5th, Segregata. 



18th class, (from the situation of the stamens on the pistil.) 1st, 

 with one stamen, as the orchis tribe of plants. 2d, as ladies' slipper. 

 5th, as the milk-weed. 6th, as snake-root. 10th, as wild ginger. 



19th class, (imperfect flowers, determined by the number of sta- 

 mens or pistils only. 1st, as bread-fruit in the natural order of fig, 

 mulberry, etc. 3d, as cat-tail, sedge, indian corn. 4th, as white 

 mulberry, oth, as genus amaranthus. Order Polyandria, as many of 

 the most beautiful forest trees, hazelnut, oak, beach, walnut, chestnut, 

 birch, Egyptian lily. 15th, Monodelphia, as cucumber, squash, water- 

 melon, pumpkin, pine, cypress. 



20th class, imperfect flowers, stamens or pistils only ; orders from 

 the number of stamens. 2d, as the willow. 5th, as hemp, hop, etc. 

 6th, green-briar, honey-locust. 8th, as poplar. 15th, as red-cedar, 

 yew, etc. 



21st class, cryptogamous plants, stamens and pistils concealed and 

 all plants not in the above classes. 1st, as ferns. 2d, as mosses. 

 3d, as liverworts. 4th, as sea-weeds, fucus, etc. 5th, as lichens. 

 6th, mushrooms. 



The 2 orders of the 14th class are known by the form of the fruit ; 

 i. e., 1st, Silicula, fruit a roundish pod and 2d Siliqua, fruit a long pod. 

 The orders of the 15th and 16th classes are known by the number of 

 stamens. The 5 orders of the 17th class are distinguished by cir- 

 cumstances of the flowers ; i. e. 1st, equalis, (stamens and pistils 

 equal ; 1 stamen, 1 pistil, and 1 seed, hence perfect,) 2d, superflua ; 

 i. e. florets of the disk perfect and of the ray with pistils only, which 

 being without stamens are superfluous. 3d, frustranea, florets of the 

 disk perfect, and of the ray neutral, which being without stamen or 

 pistil, are useless or frustrated; 4th, neccssaria, florets of the disk, 

 staminate and of the ray pistilate, which is necessary to perfect the 

 fruit. 5th, Segregata, partial calyxes or florets with a perianth, or 

 one envelop. Orders of classes 18, 19, and 20, depend on the number 

 of pistils as with the 15th and 16th ; and the orders of the 21st, cryp- 

 togamous, class are f elides, as ferns ; musci, as mosses ; hepaticce, 

 succulent mosses ; algea, as sea-weeds ; lichens, growing on old trees ; 

 and fungi, as mould and mushrooms. 



Genera. The class and order of a plant in the Linnean system 

 Having been found, the genus is the next object of inquiry. In a genus 

 having but one species, the generic description is confined to that 

 species ; but when it includes many species the description is based on 

 the parts of the species agreeing with one another. Generic descrip- 

 tions are founded on the flower or sexes and are so brief that a genus 

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