180 



COMPENDIUM OF GENERAL BOTANY. 



of the primary axis turns from the median line and develops a sec- 

 ondary branch or axis ; the secondary axis takes the direction of 

 growth of the primary axis, and finally divides again, forming an 

 axis of the third order; this third axis bears the same relation to 



the second axis as the second axis bears 

 to the first, and so on. This forms what 

 is known as a " sympodium " or pseudo- 

 axis. The rhizome of Polygonatum 

 multiflorum is a good example (Fig. 106). 

 The expression sympodium implies that 

 the organ is composed of different podia r 

 that is of shoots or branches of different 

 orders. 



Two organ -systems may be exactly 

 alike in the beginning but may by wholly 

 different in the mature state. This statement is contradictory to 

 what was said at the beginning of this chapter. It can readily be 

 supposed, and it is actually true that a spike and an umbel are alike 

 at the beginning of their formation. The attempt to co-ordinate 

 development and the mature state is liable to cause confusion. One 

 must either trace the mature state back along the line of its devel- 

 opment or vice versa, in order to have a correct understanding of 

 the true conditions. 



To trace the development of an organ-system is not always an 

 easy task. An example, which incidentally introduces us to a very 

 difficult chapter of morphology, will show that under certain con- 



FIG. 106. Rhizome of 



gonatum multiflorum. 

 a, Bud ; 6, basal portion of stem ; 



c and d, stem-scars, 

 and Landois.) 



(After Krass 



FlG. 107. (Diagramatic.) 



r 



FlG. 108. (Diagramatic.) 



ditions it is impossible to judge of the course of development from 

 a study of the mature state. Very frequently there are deviations 

 from the normal axillary branching. This I will attempt to explain 



