14 DERIVATION OF THE FLORA OF HAWAII 



PTERIDOPHYTES 



According to Hillebrand, 13 there are one hundred and fifty-five 

 species of Pteridophytes, of which seventy-nine are endemic. As in other 

 countries, a large majority of the species are ferns of the family Poly- 

 podiaceae. The most primitive of the ferns, the Ophioglossaceae and 

 Marattiaceae, are represented by five species, three species of Ophio- 

 glossum and one each of Botrychium and Marattia. 



Of the three species of Ophioglossum, one, O. pendulum, is wide- 

 spread throughout tropical Asia and Malaysia, and also occurs in South- 

 ern Polynesia. The Hawaiian plants are smaller than those usually 

 found in the East Indies, but are otherwise indistinguishable from them. 

 The identity of the other species requires further study. It may be ques- 

 tioned whether Hillebrand's 0. vulgaris is really that species. The single 

 species of Botrychium is endemic, while Marattia Douglasii occurs also 

 in Fiji. ' ' !' $ 



The characteristic family Schizaeaceae comprises a single species, 

 Schizaea robusta, also found in the Society Islands. 



The Gleicheniaceae include three species of Gleichenia, the cosmo- 

 politan G. linearis (G. dichotoma), one endemic species, and one, G. longis- 

 sima (G. glauca), a common species in the warmer parts of Asia and 

 Australasia. 



Five species of Trichomanes (three endemic) and four of Hymen- 

 ophyllum, only one of which is known elsewhere, represent the filmy 

 ferns (Hymenophyllaceae). The non-endemic species of Trichomanes 

 are widespread species of the Southern Pacific region and Eastern Asia, 

 while the only non-endemic Hymenophyllum, H. obtusum, is known 

 elsewhere only from New Guinea. 



The Hawaiian tree ferns, three in number, are all endemic, and 

 belong to the small genus Cibotium, which has representatives in both the 

 eastern and western hemispheres. 



A very large majority of the ferns are Polypodiaceae, which include 

 not only many endemic species, but also two endemic genera. One of 

 these, however, Schizostege, is sometimes considered to be not distinct 

 from Pteris. Of the non-endemic species, the great majority belong to 

 the Australasian or Indo-Malayan regions. Two species only occur in 

 America which are not found also in the Old World, viz., Asplenium 

 fragile and Pellaea ternifolia, Andean species which reach Mexico and 

 Texas. 



The only representative of the heterosporous ferns given by Hillc- 



13 Loc. cit., Introduction, p. xvii. 



