45 



and conspicuoush- tonientosc underneath with a brown wool 

 composed of branching hairlets. The last branches are 9-12 

 inches by 3-4 inches; segments emarginate or bifid, the outer one 

 (basal) pectinate or pinnatifid. The veins are prominent above, 

 sometimes uniting to form a costal areole. A distinctive feature 

 of this species is that all of the buds are enclosed between 2 small 

 but leafy, ovate, crenate bracteal leaflets. Most of the leaves 

 are spore-bearing, whereas G. dichotoma is rarely found so. 



This easily recognized species is endemic. It occurs on all the 

 islands, on open mountain ridges and in clearings in the forests, 

 at elevations of 1,000-3,000 ft. Although it is much more abun- 

 dant than the two preceding species, it is much less plentiful than 

 is G. dichotoma which is the dominant species in the Islands. 



G. emarginata shows a slight tendency toward semi-xerophytic 

 habitats, often growing in clearings and on dry ridges that are 

 much more xerophytic than the forest-lands immediately adja- 

 cent to them. It often forms very dense and impenetrable 

 tangles, which may cover areas of many square rods. 



4. Gleichenia dichotoma Hook. 



Dicranopteris linearis (Burm.) Underw.; Mertensia dichotoma 



Willd., Gaud., Brack.; Polypodium dichotomum Thunb. and 



Forster. 



This species, which occurs in many of the islands of the Pacific, 

 and in tropical countries throughout the w^orld, has become such 

 a pest in the Hawaiian forests that a detailed description seems 

 pertinent. Many of the features enumerated below are also 

 applicable, in greater or less degree, to the other Hawaiian species 

 of Gleichenia. 



The rhizome either runs along the surface of the ground, or is 

 wholly subterranean. On rocky or impervious material the 

 rhizome is aerial, but closely appressed to the substratum and 

 affixed thereto by numerous short, tough roots. In earth or mud 

 it penetrates to a depth of from 4 to 15 inches, running horizon- 

 tally and showing only the leaves above the surface of the soil. 



The rhizome is 3^ to >^ inch in diameter, terete, and of indefi- 

 nite length. Its appearance has been aptly compared with stout 



