The Natural System of Botany. 77 



ferse. The small bracts at the base of some flowers sometimes 

 indicate genera, but are not used to distinguish orders. The 

 mode in which the flowers are arranged often characterizes an 

 order. Some have their flowers in heads, some in umbels, 

 some in spikes, some in amenta, or catkins. The calyx is used 

 in several ways to distinguish orders. By its absence, as we 

 shall see, all Achlamijdeous orders are known. The number 

 of its sepals is often constant in a particular order; as in Cru- 

 cifera?, the Cabbage and Turnip tribe, they are always four, 

 and in Papaveraceae, the Poppy tribe, always two. Their 

 equal or unequal size is also sometimes an important character, 

 and their union by the adhesion of their edges is a circumstance 

 of great value. When this adhesion unites all the sepals, the 

 calyx is said to be monosepaloiqs. A character of still more im- 

 portance, is the degree of adhesion of the calyx to the organs 

 on its inside. When it grows immediately out of the disk, or 

 top of the flower stalk, and when the corolla, stamens, and 

 pistil, are quite distinct from it, having a separate point of 

 growth, the calyx is said to be inferior, that is, below the pis- 

 til. But when it adheres to the outside of the ovary, and 

 encloses it, so that the sepals appear to arise out of its upper 

 part, the calyx is called superior. As to the value of the 

 corolla in indicating affinities, it may be said that its most im- 

 portant characters are those of the adhesion or separation of the 

 petals. When these are all united into one, the corolla is 

 monopctalous, and when they are all separate, it is polypetalous. 

 This is a distinction of great value. All the Rose tribe, and all 

 the Poppy tribe, for instance, are polypetalous, and the Borage 

 tribe, and many others, are monopetalous. When no corolla 

 exists, the calyx alone being present, the plant is said to be 

 apetalous, or monochlamydeous, without petals, or having a sin- 

 gle envelope. These two characters are not, however, inva- 

 riable, since plants without petals are sometimes found in 

 orders which generally have complete flowers. When we 

 come to the stamens and styles, we find that the number of the 

 stamens is of little importance, since this, as has been before 

 mentioned, is liable to great variation among plants of the same 

 genus, or even individuals of the same species. In some 

 orders, however, the number is always invariable; but the 



