10 



BULLETIN 53, HAWAII EXPERIMENT STATION 



tion of Official Agricultural Chemists 5 were employed in making 

 the rest of the analysis. 



The results are given in Table 3, which includes also, for purposes 

 of comparison, the chemical composition of the potato and edible 

 canna, both of which are grown for commercial starch production : 



Table 3. — Comparison of the chemical composition of the tree-fern core with 

 that of the potato and edible canna tubers 



Constituent 



Tree 

 fern ( C. 

 chamis- 



soi) 



Potato 



Edible 

 canna 



Constituent 



Tree 

 fern ( C. 

 chamis- 



soi) 



Potato 



Edible 

 canna 



Water.. _. 



73. 39 

 .95 

 .06 

 1.04 



78.30 

 2. 20 

 .10 

 1.00 



72. 62 

 .98 

 .11 

 1. 40 



Fiber 



1. 57 

 22. 99 

 .24 

 3. 99 



0. 40 

 18.00 



0. 61 

 24. 28 



Protein... 



N-free extract 



Fat 



Nonreducing sugars 



Reducing sugars 



Ash... 















From Table 3 it will be seen that in chemical composition the core 

 of the tree fern is very similar to the ordinary tuber crops, and, as 

 might be expected, it contains rather large amounts of reducing 

 sugars. In view of the peculiar manner of growth of the tree fern, 

 it is very probable that the sugar content varies considerably in the 

 different sections of the core as well as in different seasons. 



The tree-fern core is apparently equal to other starch crops as a 

 stock feed. It is eaten readily by cattle and hogs, probably because 

 of its high sugar content. The new, tender fronds form the most 

 important part of the forage for stock pasturing in a tree-fern for- 

 est ; and the heart of the trunk is also eaten when it can be reached. 

 Were it not for the prohibitive amount of labor required to split 

 open these trunks, the tree fern undoubtedly would have an impor- 

 tant place among the stock feeds of the tree-fern forest districts. 



The core of the tree is not palatable as human food. It has a 

 peculiar flavor and is rather fibrous. The tender, undeveloped fronds 

 are sometimes cooked as a vegetable, but the core as such has never 

 become of practical importance. 



PHYSICAL PROPERTIES OF TREE-FERN STARCHES 



Samples of starch were prepared from the species Hapu (Oihotium 

 chamissoi), Meu (Oibotium sp.), Hapu Iii or Heii (C. menziesii), 

 and Amau (Sadleria cyatheoides) . 6 Microscopic examination and 

 photomicrographs were then made of each. The characteristics of 

 each starch as they appeared when magnified 220 diameters were 

 found to be as follows : 



(1) Hapu (C. chamissoi). (PI. V, fig. 1.) 



Size, 0.01 to 0.05 millimeter. Varying sizes in about equal proportion ; 

 shape, irregular oval, occasionally kidney-shaped, in large sizes, but circular 

 disks, with a few truncated forms in the small sizes ; hilum, annular, with a few 

 longitudinal rifts, depressed, usually central in small sizes; rings, complete, 

 very distinct, with a very pronounced ring in most of the larger granules about 

 midway between the hilum and the outer edge; polarizer, very brilliant dark 

 cross at central axis. 



5 Methods of analysis of the Association of Official Agricultural Chemists. Sec. VII, 

 p. 71. Revised to Nov. 1, 1919, Washington, D. C, 1920. 



6 The individuals of each species selected for these samples were as nearly typical speci- 

 mens as could be found. No botanical identification was made of them, since they exist 

 in comparatively pure strains, and no difficulty was had in differentiating between them. 



