July, 1921.] OGURA.— GAPS OF STELE IN POLYPODIACEAE. 115 



with leaves arranged in two rows on the upper surface." Tansley'^ 

 also says, in ferns in general, that "it may be remembered that in 

 the radial type the relative position of two meristeles changes as 

 the phyllotaxic spirals passed through, whereas in the dorsiventrg.1 

 type it is constant." These show us that in the creeping rhizome 

 leaves arrange themselves in two rows on the upper side of the 

 rhizome, while in the erect one they are arranged radially all round 

 the rhizome. Such creeping rhizomes are actually met with in few 

 cases — Microlepia pilosella, M. marginata, M. WiIfordi—h\x\ , most of 

 the creeping rhizomes have, so far as my anatomical investigations 

 have proved, spiral foliar arrangement such as % etc., just as in the 

 case of erect one, though the relation is very indistinct in external 

 appearance. This is in accordance with the observation by Conwentz."^ 

 I have once investigated the construction of the stele in Dryo- 

 pteris sophoroides, which has a horizontal rhizome with rather long 

 intemodes, even as long as 10 cm., and found that the stele is a 

 perfect dictyostelic type. Then the question occurred to me about the 

 two factors as the causes or conditions of the formation of dictyo- 

 stely. So I have examined various rhizomes of Japanese Polypodiaceae 

 and it was found that their steles were constructed almost in 

 dictyostelic type. Such cases were figured by Chandler^^ in some 

 sporelings of ferns, though he did not touch this problem. They 

 showed also the individual constancy in the stelar construction. 



Materials and Methods. 



Rhizomes of various species of Polypodiaceae, which are common 

 in the vicinity of Tokyo, were investigated. They differed from one 

 another externally as well as internally. Anatomically, they show some 

 different stelar types, such as solenostele, dictyostele, transitional 

 type between the two, Lindsaya-type,'*^ perforated and polycyclic 

 types, of which the first three will be described here. The following 

 species were investigated : 



1) Tansley, I.e. ^07, p. 191. 



2) CoNWENTZ, H. (1875) Beitrag zur Kenntniss des Stammskelets einheimischer 

 Fame.— Bot. Ztg., Jg. 33. 



3) Chandler,, S. E. (1901) On the arrangement of the vascular strands in the 

 seedlings of certain lei tosporangiate ferns. — Ann. Bot., Vol. 19. 



4) Tansley, a. G. and Lulham, E. B. (1902) On a new type of fern-stele, and 

 its phylogenetic relations. — Ann. Bot., Vol. 16. 



5) The nomenclature of Polypodiaceae is different according to various authors ; 

 I have followed that of J. Matsumttra's 'Shokubutsu-meii' (Tokyo, 1916). Some 

 synonyms and Japanese names were added. 



