1. THli in)LVP0I)IACE.4-: oF THH PHIMI'IMNI-: ISLANDS. 



INTRODUCTION. 



The Pohjpodiaccw are distinguishod from the other orders of 

 true ferns by the character of the sporangium, which is usually 

 stalked and provided with a longitudinal annulus interrupted by 

 the stalk, and opening by a stomium at right angles to the annulus. 

 In the field, and without tlic use of the microscope, they can be 

 distinguished as a rule from other ferns by the following charac- 

 teristics : 



They are rarely tree ferns, as are Marattiacew and Cyatheacece. 



They are not filmy in texture, as are HymenophyUacece. 



They are not dichotomously compound, like most of our Gleiche- 

 niacecc. 



They do not have climbing fronds, as do most of our Schizaeacece. 



In the Philippines, as elsewhere in the world, the Polypodiacece 

 are several times more numerous than are all other ferns combined, 

 and, therefore, a treatment of the order does not fall far short of 

 being an entire fern flora. 



My attempt has been to collect and publish descriptions of all 

 the ferns known to have been found in these Islands. It is likely 

 that I have fallen considerably short of this goal, for in some groups 

 the discrepancy between my number of species and the larger one 

 given by IFnderwood ^ is far greater than can be explained by any 

 difference in our interpretation of specific limits. A history of the 

 work on the ferns of these Islands would be superfluous, since the 

 subject has been well handled within the past two years by both 

 ^lerrill- and Underwood. 



While I was engaged on this work practically no ferns collected 

 bfi'ore the Ahierioau occupation were available for study in Manila. 



'Underwood, L. M.: A Summary of Our Present Knowledge of the 

 Fem3 of the Philippines. Contr. Bot. Dept., Columbia Univ., No. 20G, 

 1903. 



'Merrill, E. D. : Botanical Work in tlie Philippines. Bull. (Philippine) 

 Bureau of Agr. No. 4, 1903. 



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