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Sampson . — The Morphology of 
acts of branching at the base of the axis, which finally terminates in a cone. 
In the previous examples the duplication was due to a dichotomy of the 
branch, which more frequently forms a single tuber. 
Thus, not only is branching found occasionally in the strobilus of 
Phylloglossum , but normally in fertile plants on the production of each 
new tuber. It can, therefore, no longer be said that Phylloglossum is 
characteristically an unbranched form. 
VII. Conclusion. 
The interest which has been manifested in the monotypic genus, 
Phylloglossum , since its discovery in 1843, has centred round its most 
characteristic feature, the annual storage tuber. 
Treub saw in it a resemblance to the organ of L. cernuum , which he 
designated a ‘ protocorm,’ regarding it as of phylogenetic significance. 1 In 
this way he initiated a confusion which has been at the base of our difficulty 
in interpreting the true morphology of Phylloglossum . 
With the increase of detailed knowledge of the embryogeny of 
Lycopods, the inconstancy of the ‘protocorm ’ has been more fully realized, 
and opinion as to its primitive nature has been modified, the present 
tendency being to regard it as an ‘opportunist local swelling’, of physio- 
logical rather than of phylogenetic significance. 2 
This new conception of the ‘ protocorm ’ has not, however, helped to 
elucidate the problem of the morphology of Phylloglossum , if the old com- 
parison with the embryo of L. cernuum still be made. Except inasmuch 
as both the ‘ protocorm 5 of L. cernuum and the tuber of Phylloglossimi are 
manifestations of the tendency to local swellings seen throughout the 
family, the resemblance between them is purely superficial. 
The present work, by detailed anatomical investigation, has shown 
that the tuber of Phylloglossum is a highly specialized leafy axis, the 
terminal bud of which functions both as a means of vegetative reproduction 
and as an organ of perennation. Though different in appearance and 
structure, the tuber of P hylloglossum is comparable with the resting buds of 
L. inundatum and the ‘tubers ’ of certain Indian species of Selaginellal 
The position which Phylloglossum has hitherto occupied in the family 
Lycopodiaceae is rendered less isolated, since it can no longer be regarded 
as typically unbranched. On the other hand, the marked geophytic 
specialization, the mesarch character of the xylem, and the medullation of 
the stele, together with long established custom, justify the retention of 
separate generic rank. 
1 Treub: loc. cit. 2 Bower: loc. cit„, 1914. 
3 Bancroft, N. : Ann, of Bot., vpl. xxviii, 1914, p. <585. 
