The Anatomy of Nephrolepis volubilis J.Sm. 273 
The stolons possess a single axial polyarch exarch protostele. 
Where a stolon branches the two steles run parallel to each other 
for some distance, enclosed in the same cortical envelope, before 
they become free. This “ adnate tendency ” is also shown by the 
stolons of several other species examined. The structure of the 
stolons is remarkably uniform in the different species. 
In the endodermis of N. volubilis (stolon) peculiar strut-like 
bodies were found traversing the cells in the radial direction (PI. 
IV, fig. 2). These may serve a mechanical function. 
In the lateral plants the basal protostele becomes soon modified 
into a primitive form of dictyostele at the apex. The first leaf has 
a compound leaf-trace. 
There are no roots on the lateral plants, but it may be that 
after the lateral plants have formed their leaves at the expense of 
the mother-plant, they are shed, and strike root on the ground. 
This is suggested by numerous scars on the primary stolon. 
The primary stolons of several species of Nephrolepis (p. 268) 
are probably positively hydrotropic. 
In N. ramosa and N. altescaudens, two closely allied species 
without stolons but with scandent rhizomes the internode possesses 
the simplest type of dictyostele imaginable (viz., two strands 
separated by two leaf-gaps as seen in cross-section). In N. ramosa 
the vascular structure at the base of the branch and leaf-traces is 
almost identical, and recalls the condition in the Hymenophyllaceae, 
which has been previously used in support of the view that 
stem-stele and leaf-strand are primitively identical structures. 
In N. altescaudens the leaf-trace arises as two separate strands, 
in N. ramosa as a simple C-shaped strand. 
Sperlich’s view regarding the origin of epiphytism in the genus 
(p. 269) is well borne out by a study of N. volubilis. He regards 
the appearance of the stolon as having been the initial stage in the 
gradual emancipation of the plant from the soil. 
Velenovsky’s adoption of a new morphological category, 
the “ Achsentrager ” (shoot-bearer), to include the stolons of 
Nephrolepis, has no justification in view of the evident cauline nature 
of these organs. 
The primitive organisation of the stolon is not indicative of 
primitiveness of the genus. More probably it is an organ highly 
specialized for the conducting functions entrusted to it. 
Possibly because of the exceptionally favourable physiological 
conditions in which it is placed (connected by the stolon to the 
