42 



species, and "vvith special emphasis upon the ecological features of 

 these plants. There is nowhere in the literature a comprehensive 

 account of this group in Hawaii. The present material is based 

 upon field studies throughout the Islands during the past nine 

 years. 



The genus Gleichenia J. Sm. was named in honor of Friedrich 

 W. Gleichen, a German botanist, 1717-1783. It comprises 25 

 or more species, which are abundant in many tropical countries, 

 in subtropical eastern Asia, and also in moist situations in the 

 southern hemisphere. The taxonomic status of many of the 

 species and varieties is still unsettled, and it is entirely probable 

 that the genus is much larger than is commonly stated. One 

 species, flexuosa, has been recorded from Louisiana. The writer 

 has retained the old name Gleichenia, in preference to the modern 

 Dicranopteris, because the former is so thoroughly incorporated 

 into the literature, and because it is used in the standard flora 

 of the Hawaiian Islands, that of Hillebrand. 



The Gleichenias are all characterized by their habit of growing 

 in dense thickets. The development of the leaves is very dis- 

 tinctive. The foliage is woody and perennial, and growth is 

 indeterminate. The dichotomously branching apical regions 

 resume growth season after season, so that in some species the 

 long, trailing, vine-like leaves attain lengths of over 100 feet. 

 The pinnae are pinnatifid, with segments either small and con- 

 cave-orbicular, or pectinate and elongate. The Gleichenias are 

 noteworthy in possessing two leaf-characters which indicate a 

 very primitive condition — the striking and unparalleled dichoto- 

 mous branching of the frond, and the frequent development of 

 subsidiary pinnae between the ordinary ones. The leaves of 

 most species are repeatedly dichotomous; the ultimate branches 

 bear pinnately arranged pinnules. 



All four species are known to the native Hawaiians by the 

 name of Uluhe; Unuhe and Enuhe, sometimes used, are variants 

 of this. The English name is "Staghorn Fern," referring to the 

 branched leaves, or "Wire Fern," referring to the wiry petioles. 



In Gleichenia the sori are subglobose, and comprise 2-6 nearly 

 sessile sporangia, seated on the apex or back of a vein. Each 



