136 
DR JOHN M‘LEAN THOMPSON ON 
axis as erect is not wholly justifiable, for it seems based on the examination of 
incomplete specimens ; but the general absence of roots from the erect portion 
of the stem is supported by observations ranging in time from 1861 to the present 
day. The materials available for examination can neither support nor refute 
Mettenius’s statement that Stromatopteris is rootless. It seems probable that his 
remark on this point was fully justified by his specimens, but, should later examina- 
tion reveal the presence of roots in Stromatopteris , they will probably be found 
confined to the short, basal, horizontal or oblique portion which formed the axis of 
the young sporophyte. 
In Die Farnkrauter der Erde , p. 339, 1897, Christ referred to Stromatopteris as 
Gleichenia moniliformis (Mett.), Moore. He further noted its unique form and 
xerophytic characters, its reniform elevated receptacle, and its distribution among 
the ferruginous clay hillocks of the New Caledonian coast. 
In 1901 Boodle (“ On the Anatomy of the Gleicheniacese,” Ann. Bot., xv) ex- 
pressed the opinion that the simple pinnatipartite leaves of Gl. moniliformis and 
Gl. simplex marked these plants as reduced forms, and with regard to its protostelic 
axis further stated that Stromatopteris is the most aberrant of the G-leicheniaceae, 
“ in that no protoxylem elements are present in the mature stem, and the tracheides 
all appear to be scalariform. The absence of spiral protoxylems is interesting, 
because this species is the only one of its genus with an upright stem. It was noted 
among the Hymenophyllacese, where spiral protoxylems are general, that their absence 
in certain species of Trichomanes appeared to be correlated with an upright habit 
(T. spicatum and T. Bancroftii). Both Gl. moniliformis and the species of Tricho- 
manes just mentioned have probably been derived from forms with a creeping 
rhizome, and the change to the upright stem has been accompanied with diminished 
length of the internodes and slower growth of the rhizome. This makes it easy to 
understand the disappearance of the spiral elements.” Support for Boodle’s belief in 
an originally creeping rhizome in Stromatopteris seems ready-to hand in Mettenius’s 
original figure, and the absence of spiral protoxylems seems undoubtedly due to slow 
growth of axis in this xerophilous plant. 
In 1900 and 1902 Stromatopteris was well figured by Diels (Engler and Prantl, 
Natiirliche Pfianzen-Familien , i, 4), and in reaffirming its generic rank he laid 
emphasis on its unusual form and isolated position in the arid commons of New Cale- 
donia. In the Index Filicum of 1908, Christensen maintained that Stromatopteris 
is a distinct genus ; Bower ( The Origin of a Land Flora) commented on the simple 
pinnate form of leaf in Stromatopteris as an occasional condition among the Gleiche- 
niaceae ; and Tansley ( Lectures on the Evolution of the Filicinean Vascular System ) 
referred to Stromatopteris as an aberrant, xerophilous, and distinctly reduced 
species, comparable in this respect with Platyzoma. And finally, in 1910 (Die 
Geographie der Fame), Christ figured two plants of Stromatopteris, in one of 
which a branched leaf is shown (fig. 59), and in discussing external form he 
