82 BOTANICAL GAZETTE [july 



I 



found a triarch or tetrarch arrangement, with the three or four 

 protoxylem groups connected with metaxylem, and in the base of 

 the young plants there was a central core of xylem in the center 

 of the stele. 



Boodle 5 investigated the stem structure of L. volubile and 

 L. salakense. He regards the normal Lyco podium stele to be the 

 parallel-banded type, as in L. volubile. L. salakense has the inter- 

 mingling of xylem and phloem, resembling Gleichenia. He notes 

 that in some cases the presence of the peripheral growth of the 

 protoxylem forms a nearly continuous ring. 



The present investigation extends the range of knowledge of 

 the anatomical structure of Lycopodium by including some species 

 not studied before, which show certain phases of stelar develop- 

 ment to be especially emphasized. It emphasizes the fact that 

 the radial arrangement of the stele is quite common, and that in 

 many cases it is the original condition from which the parallel- 

 banded type is derived. While this radial arrangement is probably 

 the common one in Lycopodium, it is not the universal condition, 

 and the great variability of the stelar structures in these epiphytic 

 species deserves especial emphasis. It should also be kept in mind 

 that the greater variability in structure occurs in the stele of the 

 strobilus, while the vegetative steles remain relatively constant. 

 The presence of a great variety of types of stele, radial, parallel- 

 banded, crescentic, and that corresponding by definition to the 

 amphivasal in the same plant, and even in the same stem, as occurs 

 in L. carinatum, makes it clear that these types are more closely 

 related than has been supposed. 



Jones relates the parallel-banded type to the plagiotropic 

 stems generally, but notes that there are some exceptions, as the 

 orthotropic L. obscurum, which has the parallel-banded arrangement. 

 Holloway points out that the parallel-banded arrangement is 

 derived from the radial as a result of the branching stem. Both 

 Jones and Holloway consider the radial arrangement charac- 

 teristic of the stems of epiphytic species of Lycopodium. 



s Boodle, L. A., On the structure of the stem in two species of Lycopodium. 

 Ann. Botany 14:315-317. 1900. 



