344 
Wernham .— The Morphology of 
ported by the relative positions of the gap and of the young tuber. Further, 
the morphology of the dropper is described as being partly foliar and partly 
axial; there is a vascular ring derived from the leaf; and this is represented 
in Phylloglossum by the ring observed in the tuber of the second specimen 
examined. 1 The ‘axial ’ portion of the anatomy of the latter is, of course, 
represented by the central vascular strand ( y.t.s ., Fig. 3). 
Reasoning from analogy is admittedly dangerous ; but the remarkable 
similarity in the structure and function of the tubers under discussion and 
the c stalked bulblets ’ described in Miss Robertson’s paper seems to lend no 
little weight to the supposition that a megaphyllous leaf existed in the 
ancestors of Phylloglossum , while the position and rudimentary nature of 
the ‘ organ of Mettenius ’ is very suggestive ; it might very well represent 
the vestige of a megaphyllous leaf. 
The habit of the plant further favours this suggestion ; like the Mono¬ 
cotyledons, it is typically geophilous ; and, as Bower has pointed out, 2 this 
habit conduces to reduction in the number of leaves and enlargement of the 
individual leaf—in other words it conduces to megaphylly. 
2. The geophilous habit of Phylloglossum recalls some interesting 
parallels in other Pteridophyta. The adoption of this habit results in 
general reduction, as witness, for example, the modern pigmy descendants 
of the giant Calamarieae ; while there is no doubt whatever that Phyllo¬ 
glossum is extremely reduced, however primitive may have been the 
condition of its Lycopod ancestors ; of this primitiveness we shall, however, 
have something to say further on. The latter may have been ‘ permanently 
embryonic Lycopods ’—in which case it is not improbable that their remains 
would be as lost to us as are the embryonic stages of the ancient Lepido- 
dendra ; but their modern descendants are highly specialized in accordance 
with their special habitat. This is described in Cheeseman’s Flora of 
New Zealand as ‘barren clay hills’ in the North island, 3 and Thomas states 
that the plant flourishes best on a hill-top. 
The thickening of the epidermal cell-walls is doubtless a xerophytic 
adaptation, designed for the purpose of providing a tegument to serve as 
a protection against the environmental conditions. Sclerenchyma is, how¬ 
ever, entirely absent—a feature not surprising in so small a plant. 
Similar degradation of the protoxylem occurs in many other forms 
which occupy special habitats—notably the Equisetales, Sphenophyllum 
insigne , the leaf of Isoetes , and many aquatic flowering plants. 
3. The indefiniteness of the vascular system is also in accord with the 
habitat of the plant; and there is a striking resemblance in this regard 
between Phylloglossum and the Isoetaceae. In both cases we have 
a geophilous habit. The storage tuber of Phylloglossum is analogous to the 
thick tuberous stem of a form like Isoetes Hystrix, the storage parenchyma 
1 Supra, p. 33S. 2 Bower ( 4 ), pp. 231, 479. 3 Cheeseman (6). 
