2 



BULLETIN 53, HAWAII EXPERIMENT STATION 



the investigation, it was found that even a considerable thinning of 

 the ferns for starch production is not noticeable. The tree fern 

 falls to the ground of its own accord, or is easily pushed over, upon 

 reaching maturity, and since only the mature trees are utilized for 

 starch making, relatively few trees per acre would be cut for this 

 purpose. 



A rather extended program of work was therefore outlined, (1) 

 to determine the feasibility of planting tree ferns on cut-over areas 

 for the establishment of permanent-producing areas, and (2) to make 

 a study of the properties and uses of tree-fern starch. When it was 

 found that the rate of growth of the tree fern is too slow to make 

 it commercially practicable to replant the fern and the necessity 

 of building roads and fences to get the necessary raw material be- 

 came apparent, hopes were abandoned of establishing the industry 

 on a large and permanent basis in Hawaii. It is not unlikely, how- 

 ever, that the industry might be made a permanent one under the 

 economic conditions existing in other tropical countries in which cer- 

 tain species of the tree fern are indigenous. 



This bulletin, reporting the results of certain observations, to- 

 gether with data on the Hawaiian tree fern as they apply to its use 

 as a source of starch, has been prepared because of the scientific 

 interest which the industry has aroused and because of the potential 

 importance of the tree as an emergency crop for the island popula- 

 tion in case of interruption of shipping. 



BOTANICAL DESCRIPTION 



Rock 2 lists eight species of Cibotium, two occurring in Guatemala, 

 one in southern Mexico, one in the monsoon districts of east Asia, 

 one in the Philippines, and three that are peculiar to the Hawaiian 

 Islands. The following botanical description of the two most im- 

 portant species in Hawaii may be of interest. 3 



Cibotium menziesii. — * * * Stipes green, stout, with a ventral and two 

 lateral furrows, tuberculate and shaggy at the base with a straightish and long 

 brownish-yellow glossy pulu which changes higher up into stiff, long blackish 

 hair, and as such often covers the entire stipes ; frond with stipes 18 to 36 

 dcm. or more long and 9 to 15 dcm. or more broad, pyramidal-oblong, coriaceous, 

 naked underneath or sometimes with minute furfuraceous dots ; the rhachis 

 asperous with scattering tubercles ; pinnae with a stipe of 25 to 50 mm., oblong, 

 4.5 to 7.5 dcm. long, bearing 18 to 24 pairs of free pinnules besides the pinna- 

 tifid apex; most pinnules shortly stipitate, linear lanceolate, acute, cut half- 

 way or more, often to the rhachis at the base, into oblong rounded or entire 

 segments, which are separated by broad sinuses ; veinlets very prominent, 

 simple or forked; sori 8 to 14 on a lobe, also fringing the sinus. Involucre 

 corneous, large, a little more than 1 mm. to nearly 3 mm. in width, the outer 

 valve fornicate and large, the inner flat and narrower. 



C. chamissoi. — * * * Stipes 12 to 24 dcm., brownish, smooth, clothed at 

 the base with a pale fawn-colored lustreless, matted or cobwebby pulu, fur- 

 furaceous or naked above; frond 12 to 24 dcm. long, chartaceous, the under 

 face green or dull glaucous and generally covered with a pale cobwebby pubes- 

 cence ; lowest pinnae 4.5 to 7.5 dcm. long, with 24 to 28 pairs of pinnules, these 

 shortly stipitate, linear lanceolate 12.5 to 15 cm. by 16 to 20 mm. acute, the 

 lower ones cut to near the rhachis into oblong, straightish, rather obtuse seg- 

 ments with narrow sinuses, the basal segments entire and not deflected; 

 veinlets little prominent ; sori 8 to 14 to a segment, the involucre small about 

 1 mm. wide, chartaceous. 



2 Rock, J. F. The indigenous trees of the Hawaiian Islands, p. 89. 



* Rock, J. F. The indigenous trees of the Hawaiian Islands, pp. 91-93. 



