l<2i TRUE FORMATION OF THE GENERA. 



The nectarium nature has made of the greatest consequence. 

 This part, which had not even a name, till Urinous had distin- 

 guished it, is a decisive mark in all the following genera, viz. 

 in Orchis... Satyrium...Monotropa...Fumaria.., Viola... Mal- 

 pighia...Bannisteria...Adenanthera...Commelina...Laurus... 

 Helxine... Dictamnus... Zygophyllum... Swertia... Lilium... 

 Fritillaria... Hydro phyllum ... Ranunculus ... Hermannia... s , 

 Berberis...Staphylea...Passiflora... Narcissus... Pancratium 

 ... Mirabilis.... Nerium.... Stapelia....Asclepias... Diosma... 

 Campanula ... Plumbago ... Hyacinthus ... Rhododendrum... 

 Cheiranthus... Sinapis;.. Kiggelaria... Clutia... Aq.uilegia... 

 Nig ella. . . Aconitum . ..Parnassi a. . .Epimedium . . .Theobroma... 



RESEDA...GREWlA...HELLEBORUS...IsOPYRUM...TROP J EOLUM...and 



Impatiens. 



The stamina and calyx, being less subject to luxuriancy, are 

 far more certain than the petals. 



The corolla varies as to its figure in many genera; as in Vac- 

 cinium... Pyrola. ..Andromeda... Nicotiana... Menyanthes.., 

 Primula. ..Veronica ... Gentiana... Hyacinthus ... Scabiosa... 

 and Narcissus. It varies also as to number, being in Ranuncu- 

 lus pentapetalous in some species, and polypetalous in others; ... 

 in Helleborus also, pentapetalous and polypetalous in Statice, 

 pentapetalous and monopetalous ;...and in Fumaria, dipetalous and 

 tetrapetalous;... and the number' is also sometimes variable in the 

 same species ; ^is is observed in Carica, and Jatropha. 



The structure of the pericarpium was formerly thought to be 

 of great consequence in determining the genera ; but there are 

 examples without number that demonstrate the contrary. There 

 are a great many genera that have been established on distinc- 

 tions in the pericarpium, and that are now rejected ; of these 

 we shall give an ample list in Chap. XXXIII. 



The characters of luxuriant flowers, whether barren* or mu- 

 tilate, cannot be allowed any place in determining the genera; 



* Barren flowers are such as have lost the stamina, which is the case of full 

 Hewers. Mutilate are those that are incomplete, wanting the corolla or perianthhrni- 



