346 
Wernham .— The Morphology of 
The striking similarity of the development of this plant to the 
embryonic stages of Lycopodium has led many to regard it as a ‘ per¬ 
manently embryonic form of Lycopod ’. This has led to the conclusion that 
Phylloglossum is a relatively primitive form, and this receives a certain 
amount of support from the gametophytic characters ; but the fact that 
more than one tuber may be formed in a season, with the consequence that 
the tuber is probably a merely adventitious organ of vegetative reproduction, 
seems to militate very forcibly against such a conclusion. 
The anatomy, moreover, seems to point to extreme specialization. 
The latter is, doubtless, largely biological in significance, and comparatively 
recent in descent; but the gap in the upper part of the stem-stele can 
scarcely be regarded as other than an ancestral character, and one of 
considerable importance. 
If the gap is a leaf-gap, as seems by no means unlikely, then Phyllo - 
glossum is no more primitive than Tmesipteris or Ophioglossum Bergianum ; 
in fact, it is less primitive, for reduction has led to the complete suppression 
of the megaphyllous leaf in Phylloglossum . 
This suppression is not without parallel in the Pteridophyta. In recent 
Equiseta the leaves are extremely reduced, but the gaps in the stele are 
now generally admitted to be leaf-gaps. 1 In Ophioglossum simplex we have 
an exact parallel with the suggested condition in Phylloglossum , for, although 
leaf-gaps are present in the stele of this species, the megaphyllous sterile 
laminae which cause them, so to speak, are altogether absent; and as 
Bower points out, ‘ it is thought that O. simplex forms the end of a series 
of reduction of the vegetative system, consequent on . . . habitat: that as 
0 . intermedium . . . shows . . . only a reduced lamina, so in O. simplex the 
reduction having proceeded further has resulted in the complete elimination 
of the sterile blade.’ 
It is suggested that Phylloglossum stands at the end of a similar 
reduction series, of which the transitional forms have been lost. If this be 
so, we can no longer regard it as a primitive form, at least, so far as the 
vegetative organs are concerned ; while in specialization for spore-dispersal 
it stands as high as any of its Lycopodinean allies. 
We may summarize our conclusions briefly thus :— 
1. In view of its anatomical structure, Phylloglossum , like Tmesipteris , 
is ‘ microphyllous ’ in its lower portion, and ‘ megaphyllous 5 in the upper— 
thus occupying a position intermediate between Pteropsida and Lycopsida. 
2 . The general degradation of the vascular system, coupled with the 
geophilous habit, suggests that Phylloglossum has undergone considerable 
reduction recently in descent. 
1 Gwynne-Vaughan ( 7 ); but Jeffrey (8) is a notable exception to this statement. 
