48 



nules shorten toward the base; the lowest one on the outside is 

 deflexed and generally larger, crenate or pinnatifid. At the base 

 of each bare forking or bifurcation there is a pair of smaller 

 lateral pinnules. The lateral pinnules are of varying sizes, the 

 lower ones often equal to the frondose branches; the upper re- 

 duced, crenate, or even subentire. The veins have 3-5 parallel 

 branches. 



The pinnules unroll as they mature, the young leaves or leaflets 

 being readily recognized by the rolled tips of the pinnules, and 

 by their pale green color. The maturing leaflets are strongly 

 and rigidly deflexed, so that usually the center of the leaf is 

 noticeably higher than the peripheral parts. This doming of 

 the leaf give the Gleichenia thicket a characteristic scalloped or 

 hummocky appearance.* 



The sori are of 10-12 sporangia, and are seated on the middle 

 of the anterior veinlet. The sporangia are sessile, with a very 

 wide complete ring, which opens by the separation of two joints. f 



The petioles of uluhi (to use the convenient Hawaiian name) 

 are so woody and elastic and the blades so coriaceous that the 

 dead leaves form a massive, resistant part of the thicket. Upon 

 death the leaves do not fall or break, except through mechanical 

 injury, but remain erect, their blades interlocked with the living 

 fronds. Gradually the latter rise above the dead leaves, so that 

 a vertical section of an tduhi thicket shows a canopy of living 

 leaves surmounting and masking a woody jungle of dead foliage. 



The general color efl^ect of uluhi is a clear, bright, yellow-green. 

 The yellowish constituent Is conspicuous, particularly in the 

 young foliage. An uluhi thicket contrasts strikingly with the 

 heavy green of the lehua {Metrosideros polymorpha), the gray 

 green of the koa {Acacia koa), or the silver green of the kukui 

 (Aleurites Moluccana) , common trees with which It Is often asso- 



* Hilletjrand suggests that whenever the lateral pinnules are large and deeply 

 divided the lowest outer segments of the frondose pinnae are likewise, only in a less 

 degree, suggesting the idea that the former are in reality only the lowest segments 

 of an otherwise aborted frond or pinna. 



t For the development of the prothallium see N. W. P. Rauwenhoff, La genera- 

 tion sexuee des Gleicheniacees. Archives Neerlandaises des_Sciences exactes et 

 naturelles, t. 24: 157, 1891. 



