Site te aa ge (ei 
ROBINSON: PTERIDOPHYTA OF THE HAWAIIAN IsLANDs 575 
ing the vein which connects the tips of the otherwise free veins: 
indusium double, the outer formed from the incurved margin of 
the frond, the inner attached to the receptacle on the inner side 
and enclosed by the outer indusium, both ciliate at the margin. 
Type species: Pieris aquilina L. 
* PTERIDIUM AQUILINUM (L.) Kuhn; v. Decken, Reisen Ost. Afr. Bot. 
il... 1879 
Pieris aquilina L. Sp. Pl. 1078... 1784. 
Cincinalis aquilina Gled. Syst. Pl. 290. 1764. 
Asplenium aquilinum Bernh. Jour. Bot. Schrad. 1799': 310. 1799. 
Pieris psittacina Presl, Del. Prag. 185. 1822. 
Pieris arachnoidea Kaulf. Enum. 190. 1824. 
Allosorus aquilinus Presl, Tent. Pterid. 153. 1836. 
Eupteris aquilina Newman, Phytologist 2: 278. 1845. 
Paesia aquilina Keyserl. Polyp. Cyath. Herb. Bung. 22. 1873. 
Ornithopteris aquilina J. Sm. Hist. Fil, 298. 1875. 
TYPE LOCALITY: Europe. 
DISTRIBUTION: Common through tropics and North Tem- 
perate zones. 
ILLUSTRATIONS: Diels, in E. & P. Nat. Pf. 1: 296. 1899; 
Waters, Ferns 93. 1903. 
SPECIMENS EXAMINED: Hawaii, Baldwin 17; Mauna Loa, 
Wilkes Expedition C; Maui, Bailey go C; Kauai, Heller 2416 C; 
4o C; Hawaiian Islands, Baldwin 20 C, N ; ex Herb. John Donnell 
Smith 77. 
In the Olinda woods at 1,300 m. elevation on Mt. Haleakala, 
Maui, plants of Pteridium aquilinum attain such size that it seems 
hardly possible that they are of the same species as the dwarfed, 
leathery, and resistant forms that grow upon the exposed rocks at 
from 2,000 m. to 3,000 m. elevation. Further study may show 
that they are distinct species, but for the present their differences 
must be considered ecological rather than taxonomic. 
4. PELLAEA Link, Fil. Sp. 59. 1841 
Xerophilous plants, usually found upon rocks. Rootstock 
short, erect; leaves cespitose, articulate; blades consisting of 
I to 3 nearly uniform leaflets; sori marginal, borne upon the ends 
