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. N"otable illustrations of this are DavalUa clecurrens (Fig. 1), 
DipJaziuni polypodioides^ Asple7num siibnormaU, A. resecturn, A. te- 
iierum, A. Belangeri, A. macro phyllum, etc. Merely channeled are the 
stipes of Stenosemia, Ilumata parvula and Lindsaija dccoinpo.sUa; the 
rachis of Nephrolepis cordifoUa, Stcnochlaena suhlrlfoUata, Blechnum 
cgrcgium and Folypodium angiistalum; the racliis and stipe of DavalUa 
pallida, Microlepia striyosa, Diplaznim pallidum, 1). lomenlusu}ti (?), 
D. dolichosorum, etc., Athyrium silvaticum, Fleris cnsifonuls, P. pluri- 
caudata, etc., Taenitis, Pohjpodiaifi pahnatum, etc.; the brandies of the 
rachis of Odontosoria; the rachis and costae of Schizostege calocarpa; the 
costai of Oleandra neriiformis and Pohjpodium revolulum; and the veins 
of Nephr odium sparsum. and other species. The costa of Polypodia^ 
1741 {P. musacfolium ?) is triangular in section, a flat side raised well 
above the level of the frond, wliile 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 ba*se of the succeeding pinna; Nephrolepis 
cordifoUa is an illustration. 
The convexity of the major areolae of Polypodinm affine and P. liera- 
dcum 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 holding of much water, and the ready agitation brought 
about by any movement of air, San Eamon ferns with very fine, ultimate 
divisions are Nephrodium sctigerum, Psomiocarpa apiifolia, Lindsaya 
hymenophylloides, L. hlumcana, Diplazinm meyenianum, Aspleninm 
Belangeri, A, scandens, Onychium, Monogramiaa (whole frond) and 
Pohjpodium 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 Blechvum egre- 
glum, the pinnse of Nephrodium canescens, and the ultimate pinnules 
of Nephrodium setigerum, Dennsiaedtla cuiieala and Diplazium pohj- 
podioides. To reach the nether surface of any of these structures water 
would have to run uphill from the margin. 
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