198 ALLIANCES OF PLANTS. 



CLASS I. EXOGEN^E. 

 The Subclasses are 



COMPLETE PLANTS ; with both their calyx and corolla perfect ; or at 

 least with the calyx highly developed, if the petals are absent : 

 these divide into 



1. POLYPETAL.E, with the petals distinct. 

 3. MONOPETALJE, with the petals united into a tube. 

 2. INCOMPLETE PLANTS; in which there is no corolla; their calyx is 

 generally either but little developed or altogether absent. 



No division of Exogens has been discovered more in accordance with natural affinities, 

 than that which depends upon the different degree of developement of the flower ; it is 

 true, indeed, that its characters are not always constant, and that practical difficulties 

 arise from the circumstance of some genera belonging to polypetalous orders having no 

 petals, while a portion of some monopetalous orders are actually polypetalous, and so on. 

 Nevertheless the arrangement founded upon the distinctions above recorded appears to be 

 natural, if the latter are rightly considered. 



As understood by me, all those orders in which the floral envelopes are herbaceous, and 

 imperfectly developed, belong to Incompletae, whether there are two rows or not, as Me- 

 nispermaceae : nor ought others, as Euphorbiaceae, to be removed from Polypetalae ; be- 

 cause, although the mass of such orders is polypetalous, certain European genera, with 

 which we are best acquainted, have no petals. With regard to those polypetalous orders, 

 in some genera of which the petals cohere by their edges, so as to resemble a monopeta- 

 lous corolla, the only means of recognising them is by observing that their petals are 

 scarcely joined at the base ; there is this, however, which assists in removing the diffi- 

 culty : in true monopetalous orders the style is scarcely ever divided, except just at the 

 point, and their fruit is therefore, in all cases, syncarpous ; while, in those polypetalous 

 genera, which take on a monopetalous appearance, the fruit is in reality apocarpous, as is 

 the case with Anonaceae, Crassulaceae, Leguminosse, Meliaceae, Rutacese, &c. The two 

 latter, although syncarpous when young, yet become truly apocarpous as their fniit ripens. 



SUBCLASS I. POLYPETAL.E. 



These comprehend the following groups : 



1. Albuminosa:. Embryo very considerably shorter and smaller than the 

 albumen. 



2. EpigynoscB. Ovary inferior, usually having an epigynous 



disk. 



3. ParietostB. Placentae parietal. 



4. Calycosa. Calyx incompletely whorled; two of the sepals 



being exterior. 



5. SyncarposcB. None of the characters of the other groups, 



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II 



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and with the carpels compactly united. 



6. GynobaseoscB. Carpels not exceeding five, diverging at the 



base, arranged in a single row around an elevated axis, or 

 gynobase. Stamens usually separate from the calyx. 



7. Apocarposa. None of the characters of the other groups, 



but with the carpels distinct ; or separable by their faces ; 

 or solitary. 



-In the succeeding pages the first column contains a brief character of the 

 der; the second the name of the Order; the third its sensible properties, 

 with some officinal example in italics within brackets, when any is to be found. When 

 J third column is blank, nothing is known of the sensible property. 



