wh\ hill— anatomy OF LYCOPODIUM 83 



The present investigation shows that not all of the epiphytic 

 species are characterized by the radial arrangement of the stele, 

 since L. verticillatum has generally the parallel-banded type. 

 Further, it shows that not only may both radial and parallel- 

 banded types occur in the same stem, associated with crescentic 

 and amphivasal, but that these changes from one arrangement 

 to another are independent of the branching of the stem, as seen 

 in L. carinatum, L. Phlegmaria, and L. varium. Branching does 

 induce change from radial to parallel-banded arrangement, but 

 this change may also occur without branching. 



There seems to be a general opinion, as expressed by Tones 



Hollow 



may be com 



•ge number of protoxylem points, and this 

 )letely justified by evidence drawn from the 

 study of the young sporophytes. In the mature plants, in some of 

 the species used in this investigation, the parallel-banded arrange 

 ment occurred where there were but 2. x. and a nrotoxvlem ooints 



arrangement 



em 



In these species the parallel-banded arrange- 



seems 



of protoxylem points as in those studied by Jones and by Hollo- 

 way, where it was associated with a large number. 



Boodle regards the parallel-banded arrangement as the normal 

 Ly co podium stele, but from this study it seems unsafe to regard 

 any particular type of bundle arrangement as normal, since it will 

 depend upon the level at which the stem is cut, or how near the 

 section is to the point of branching as to what type of stele is found, 

 for all the known Lycopodium steles may be found in the same stem 

 excepting the so-called " mixed 7 ' stele. 



Attempts have been made to connect the factors determining 

 the stelar development with the type of stele found in the various 

 species of Lycopodium. Plagiotropism has been suggested as 

 being the factor favoring the formation of the parallel-banded 

 type of stele, and orthotropism that favoring the development of 

 the radial stele, but so many exceptions are to be found to these 

 statements that they seem to lose significance. The conditions 



