1914] HILL— ANATOMY OF LYCOPODIUM 81 



between the protoxylem points and between the xylem bands 



(fig. 28). 



Discussion 



Jones, 2 in an investigation of about a dozen temperate and 

 tropical species of Lycopodinm, found that the radial arrangement 

 of the stele is very characteristic, especially in young plants. He 

 says "the principal feature observed in sections of the young 

 stem is that the vascular bundles present a triarch or tetrarch 

 arrangement exactly similar to the structure which may be found 

 in roots. 7 ' He also states that it has always been suggested that 

 this arrangement represents a very primitive type of stele. Jones 

 also divides the mature stems into two categories: parallel-banded, 

 connected with a high number of protoxylem groups; and a second 

 type characterized by a promiscuous mixture of xylem and iso- 

 lated phloem patches, which he regards as characteristic of tropical 



s 



epiphytes. 



Holloway, 3 in a study of the young sporophytes of six New 

 Zealand species of Lyco podium, classifies them as follows in regard 

 to the type of stele: (1) a "mixed" type, with indiscriminate 

 mixture of xylem and phloem; (2) a radially banded type, with 

 the radial arrangement of xylem and bands of phloem situated 

 between the xylem radii; and (3) the parallel-banded type, with 

 the xylem and phloem arranged in alternating bands across the 

 cylinder. He notes that the radial and parallel-banded types are 

 closely related and may pass into one another, and that the latter 

 is associated with a relatively high number of protoxylem points, 

 5-9 he says being sufficient to give that arrangement. 



Wigglesworth, 4 from a study of young sporophytes of L. com- 

 planatum and L. clavatum, concludes that the radial arrangement 

 of xylem and phloem occurring in upright forms of Lyco podium 

 is the more primitive condition. In the upper part of the stem she 



2 Jones, C. E., The morphology and anatomy of the stem of the genus Lyco podium. 

 Trans. Linn. Soc. II. 7:15-35. pis. j-5. 1905. 



* Holloway, J. E., A comparative study of the anatomy of six New Zealand 

 species of Lycopodinm. Trans. X. Zeal. Inst. 42:356-370. pis. 32-34. 1909. 



4 Wigglesworth, Grace A., The young sporophytes of Lycopodinm complanatum 

 and Lycopodinm clavatum. Ann. Botany 21:211-234. pi. 22. 1907. 



