426 Bower.—Studies in the Phytogeny of the Fi lie ales. 
I also received material of P. glauca, (Bl.) Mett. There is also in my hands 
material apparently of P. pycnophylla , collected by Dr. Lang on the Malay 
Peninsula. It is upon these supplies that the following description is based. 
External Characters. 
The stock in all of the species examined was upright and relatively 
massive, with a habit similar to that of the Osmundaceae; it projects 
above the soil for some inches to a foot in height, and is entirely covered 
externally by the persistent bases of the leaves of former seasons, which 
are enlarged, and coated with dark sclerenchyma. Occasionally the axis 
bifurcates, the branching being clearly dichotomous ; this was specially 
observed in several examples of P. semicordata . In P. pycnophylla dicho¬ 
tomy was not seen, but here and there stolons are found attached to the 
stock ; these may be attenuated at their base, taking there a horizontal or 
oblique course, and bearing at first only stunted scale-leaves ; but sooner 
or later (and in some cases without any attenuated basal region at all) the 
stolon expands into a massive trunk, bearing numerous and more closely 
disposed foliage leaves. A formation of stolons was also observed in 
P.glauca , in essentially the same way as in P. pycnophylla, while dichotomy 
was not seen in that species. Stolons were not observed in P. semicordata. 
From the specimens examined it would thus appear that the terminal 
dichotomy of P. semicordata , and the lateral formation of stolons, as in 
P. pycnophylla and glauca , are complimentary methods of increasing the 
complexity of the shoot-system ; P. semicordata has apparently retained 
the more direct and primitive, and P. pycnophylla has adopted a more 
indirect and probably a more recent method of carrying this out. 
The leaves are of the simple pinnate type characteristic of the genus 
Blechnum , but they present several points of special interest, for the most 
part already noted by Mettenius ; these are here detailed afresh in order 
to fill in the picture of the habit of the genus. The leaves form a dense 
terminal rosette, being arranged on a spiral plan which increases in 
complexity as the axis enlarges distally. There is a sharp differentiation 
of the broader sterile from the narrower and often longer fertile fronds. 
The foliage leaves are of a rather rigid texture in both species, while in 
P. semicordata there is a marked serration at the distal end of the pinnae 
(compare Mettenius, 1 . c., Taf. XV, Fig. 1); this is less marked in the 
leaves of P. pycnophylla (compare Kunze, 1 . c., Taf. CXXV). The leaf-base 
in both species is enlarged, widening out laterally, and thickening in 
a marked degree ; on the abaxial side it bears a projecting flange, which 
is specially prominent in P. pycnophylla ; on either side of this, but not 
maintaining any degree of regularity in number or in position, are the 
well-known ‘ aerophorae ’ of Mettenius, which appear in the mature leaf as 
projecting brownish masses of pulverulent tissue leading through the dense 
