33 
Many ferns have very narrow, erect wings, continuous along the rachis, 
or along the rachis and stipe, opening laterally at the insertions of the 
pinnae. Notable illustrations of this ar e. Davallia decurrens (Fig. 1), 
Diplazium polypodioides , Asplenium subnormale , A. resecturn, A. te- 
nor urn, A. Belangeri, A. macrophyllum, etc. Merely channeled are the 
stipes of Stenosemia , ILumata parvula and Lindsay a decomposita; the 
rachis of Nephrolepis cordifolia, Stenoclilaena subtrifoliata, Blechnum 
egregium and Polypodium angustaium ; the rachis and stipe of Davallia 
pallida , Microlepia strigosa, Diplazium pallidum, D. tonientosum (?) , 
D. dolichosorum , etc., Athyrium silvaticum, Pteris ensiformis, P. pluri- 
caudata , etc., Taenitis , Polypodium palmatum, etc. ; the branches of the 
rachis of Odontosoria; the rachis and costae of Schizostege ■ calocarpa ; the 
costae of Oleandra neriiformis and Polypodium revolutum j and the veins 
of Nephrodium sparsum and other species. The costa of Poly podium 
1741 ( P . musaefolium ?) is triangular in section, a flat side raised well 
above the level of the frond, while the third angle stands out sharply 
below it. 
An effect similar to that of the winged stipe is produced by the 
auricles of the pinnae of some species standing close to or against the 
rachis and each underlaying the base of the succeeding pinna; Nephrolepis 
cordifolia is an illustration. 
The convexity of the major areolae of Polypodium affine and P. liera- 
cleum can conduct water along the main veins and costae, just as a wing 
convex as a whole does, and the rows of close-set . papillae on the segments 
of P. papillosum must operate in the same way. 
Irrespective of the ease or difficulty of becoming wet (as a matter 
of fact, for a reason which I shall presently develop, cut, incised and 
dissected fronds shed water), finely dissected fronds dry readily by 
evaporation. There are two reasons for this; the limited single surfaces, 
preventing the 1 holding of much water, and the ready agitation brought 
about by any movement of air. San Ramon ferns with very fine, ultimate 
divisions ar e Nephrodium setigerum , Psomiocarpa apiifolia, Lindsaya 
liymenophylloides, L. blumeana, Diplazium meyenianum, Asplenium 
Belangeri, A. Scandens, Onychium, Monogramma (whole frond), and 
Polypodium gracillimum. ' 
Dryness of nether surface. — Aside from these general adaptations to 
promote the facile escape of water from the frond, there are various 
other devices which prevent the passing of water to its nether surface. 
A very simple structure of this kind is the convexity of the ultimate 
divisions of the frond, such as that of the segments of Blechnu?n egre- 
gium , the pinnae of Nephrodium canescens, and the ultimate pinnules 
of Nephrodium setigerum , Dennstaedtia cuneata and Diplazium 'poly- 
podioides. To reach the nether surface of any; of these structures water 
would have to run uphill from the margin. 
