4 i 6 Bower. — Studies in the Phytogeny of the Fiticales. 
a genus of less certain affinity with the Blechnoid Ferns (Ann. of Bot., 
vol. xxiv, p. 423, &c.). In the genus Blechnum both creeping and compact- 
upright stocks are represented, while many species have an intermediate or 
ascending position ; there is a preponderance of erect or ascending species 
over those of creeping habit, while not a few are definitely subdendroid. 
From the creeping habit an easy transition has been to the climbing con- 
dition, which appears in B. attenuatum , filiforme , and volubile , but finds 
its fullest development in § Stenochlaena. Of the Blechnoid derivatives, 
W oodwardia , Doodia , and Brainea show a preponderance of the compact, 
upright, or ascending habit, and it is shared in some degree by Asplenium 
and Scolopendrium . 
There is nothing very distinctive in the facts relating to this feature. 
But it is material to note that the subdendroid habit, which is common, 
accords well enough with what is seen in the Cyatheoid Ferns, with which, 
through Matteuccia , a phyletic relation would exist if the comparisons given 
in the above pages are valid. On the other hand, the creeping habit has its 
prototype among the Cyatheoid Ferns in Lophosoria , and ultimately in the 
Gleicheniaceae, where it is the prevalent condition. In a previous memoir 
(Ann. of Bot., vol. xxvi, p. 293) it was concluded that the creeping was the 
relatively primitive type in the Cyatheoid series, and the upright the 
derivative state. A similar view may now be extended to the Blechnoid Ferns. 
The leaves in the majority of the series show no peculiar basal develop- 
ments such as are seen in Plagiogyria. But in Matteuccia intermedia the 
petiole does widen out towards the base, showing thus some degree of 
similarity to that isolated genus. There is a preponderance of the simple 
pinnation, though frequent marginal serrations indicate a potential further 
branching, which is actually realized in the doubly pinnate Sadleria , in 
B. Fraseri , and in the climbing B. volubile. Such facts accord readily 
enough with a derivation of the relatively simple leaf-forms by condensation 
from a more fully branched Cyatheoid type, as do also the facts of the 
venation. This is of an open forked type, connecting downwards with 
a marked midrib. In some cases fusions of the veins occur in the expanded 
sterile lamina, as in Woodzvardia areolata\ such cases may, with Onoclea 
sensibilis , be held to be, as regards their venation, relatively late and deriva- 
tive states. In the sorophylls of Blechnum and its derivatives the formation 
of soral commissures becomes a marked and constant feature ; this will be 
specially taken up later in relation to the sorus. Putting it for the moment 
on one side, the preponderating type of venation in the Blechnoid Ferns is 
of an open forked type — as in the Cyatheoid and Gleichenioid Ferns ; and 
vein-fusions are only occasionally met with in isolated species. Such facts 
indicate for the family a relatively primitive position. 
But the most characteristic feature of the leaves for purposes of com- 
parison is the heterophylly (dimorphism or trimorphism). It may be 
