420 Bower. — Studies in the Phytogeny of the Filicales. 
alpinum differ from this only in the number of the leaf-gaps traversed 
in a single section, and such minor details. The same may be said also for 
Matteuccia intermedia. In the climbing species ( B . filiforme and Steno- 
chlaena sorbifolia ) a similar arrangement is found, but with the proportions 
of the strands, and especially of their xylem, much larger, and with the 
gaps narrower ; while in accordance with the climbing habit the roots tend 
to be concentrated on the side next the support, where an unusually large 
meristele may sometimes be found. The Blechnum type also extends 
to Woodwardia and Doodia, and it is found to underlie the structure seen 
also in S colop endrium and Asplenium. But there is little in the character 
of the dictyostele of any of these which can be laid hold of for comparative 
purposes. 
The leaf-trace provides more interesting material. The relatively 
3 -y- 
Text-fig. 20. Transverse sections of the petioles of various Ferns of the Blecbnoid series. 
(1) Matteuccia intermedia ; (2) Asplenium celtidifolium ; (3) Blechnum Fraseri\ (4) Blechnum 
attenuatum ; (5) Blechnum tabulate ; (6) Blechnum brasiliense ; (7) Brainea insignis ; (8) Wood- 
wardia radicans ; (9) Sadleria cyatheoides. 
primitive type of this series is the leaf-trace of two equal strands, right and 
left. It is seen in Matteuccia, and in B. Patersoni , tabid are, spicant , 
attenuatum, alpinum, filiforme , and punctulatum ; also in Doodia, Scolo- 
pendrium, and Asplenium. It may readily be regarded as derived from 
a single strand of a trace of a type such as is seen in Plagiogyria (Ann. of 
Bot., xxiv, p. 430, Text-fig.). In some cases, as in Matteuccia, B. Pater- 
soni, spicant , alpinum, and filiforme, and many species of Asplenium, such as 
A. marginatum , the two leaf-trace strands maintain their identity undivided 
for a considerable distance. But in others they subdivide soon to form 
a ‘horseshoe’ of which the lateral strands are larger and hooked. This is 
seen in B. tabulare , attenuatum , punctulatum , brasiliense, in Brainea and 
