CHAPTER XXXIV. 
OSMUNDACEAE. 
THE Osmundaceae are represented by the living genera Osmunda and 
Todea, while certain species of the latter are sometimes separated under 
the generic name of Lepfopterts. The number of species is ten. The order 
is of wide geographical distribution, but outside the limits of the ice-cap 
of the glacial period. The plants are all perennial, with an upright, but 
usually short stock, which bifurcates occasionally. The axis is covered by 
the persistent and winged bases of the leaves, which are disposed upon 
it in a dense spiral. The attachment to the soil is maintained by numerous 
stout and darkly-coloured roots, which originate in close relation to the 
leaf-bases. The leaves expanded in the current year form together a shuttle- 
cock-shaped group, the outermost of which are often sterile, and the inner 
fertile ; but some of the leaves never attain full development, their lamina 
being abortive: these lie at the outside of the winter bud, and their basal 
region, which remains* persistent, acts as a scale-like protection to those 
within. The leaves show the usual circinate vernation, and are covered 
while young by mucilage-secreting hairs, which take the place of ramenta. 
These hairs fall off as the leaf expands, leaving a smooth surface. The 
leaves themselves are singly or doubly pinnate. In TZodea there is no 
marked difference between the fertile and the sterile regions, but in 
Osmunda the sporangia are localised on various parts of the leaf, which 
then show a considerably smaller expansion of surface (Fig. 293). There 
is a difference of texture of the leaves which has given the basis for the 
recognition of the third genus, Lepfopteris: while Osmunda and Todea 
barbara have leaves of a leathery character, those ‘species from Australasia 
and the South Sea Islands which are grouped under Lepéopteris show a more 
or less thin and pellucid structure of the pinnules, an approach to the 
“filmy” character seen in the Hymenophyllaceae. It is, however, a question 
whether this difference deserves generic recognition. It is probably a 
relatively direct and recent adaptation to life under conditions of excessive 
moisture. The leaves of Ferns are typically winged structures throughout 
