138 



TAXONOMY. 



suits according to the theory, which may be employed also in 

 practice ; because a character which, considered by itself, has 

 a small value, may assume a very important value, if we con- 

 sider it with respect to the whole organization of a tribe or 

 family. This character then becomes the sign of a permanent 

 internal variation of structure, which must be of great conse- 

 quence. The form of the leaves is in itself of small value in 

 classification ; but in the Grasses, for instance, it has a very 

 important significancy, because it is inseparably connected 

 with the internal organization. If we knew the internal 

 structure of all plants, these relations in many families, for 

 instance in the Rubiaceae, the Leguminosas, and the Ferns, 

 would be completely cleared up. 



209. 



If, in a tribe, we observe certain plants which are nearly 

 related to each other by their general aspect as well as by 

 their other characters, but Avhich are distinguished from one 

 another by one mark, this mark cannot be of any great con- 

 sequence. In the Saxifragese, the superior or inferior posi- 

 tion of the fruit, when the other characters correspond, is of 

 just as little consequence as the upright position of the em- 

 bryon in the Berberideae, where it is often also inverted. The 

 Aggregatae, again, are distinguished from Compound flowers 

 by this permanent character, among others, that in the for- 

 mer the embryon is inverted, in the latter it is upright. 



CHAP. VI. 



NATURAL ARRANGEMENT OF FAMILIES. 



SIO. 



I. Plants of a cellular Structure. Scarcely proper Seeds. 

 Propagated by Sporag. 



Fam. 1. Fungi. (Introd. II. Fig. S%) 



a. Conyomici, Nees von Esenbeck. 



b. Nematomyci. 



