476 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



According to Christ Alsopliila elongata is thus utilized in Colombia, 

 and the trunks of Dicksonia Sellowiana in Brazil by planters in 

 making inclosures for their farms. In Colombia Mr. Frank M. 

 Chapman has observed the occasional use of tree fern trunks "pos- 

 sibly 14 feet in height above the surface of the ground" as telegraph 

 poles, although as a rule bamboos are ordinarily there used for this 

 purpose. 



Still another use is made in Hawaii of Cibotium trunks, which, as 

 mentioned above, there grow to such enormous proportions. Mr. 

 Henshaw states that it is a common practice to make trails, 1 to 5 

 miles long, leading through the woods to the coffee plantations in 

 the mountains, entirely out of Cibotium trunks, either whole or 

 split in halves. He adds that the coarse thick covering of adven- 

 titious roots provides a springy, well-drained surface for walking, and 

 that trails thus constructed, by the convenient use of these trunks 

 as a rough and nearly indestructible planking, afford ready access 

 to plantations through wet forests which, otherwise would prove 

 almost impassable. 



THE LEAVES. 



Considerable attention has been devoted thus far to a consideration 

 of the rhizome, which has been found to assume different forms of 

 growth and to vary greatly in nearly all respects. A similar diversity 

 is exhibited also by the leaves or, as they are commonly called, the 

 fronds. Of the two tribes between which the North American species 

 are divided, the Cyathese and Dicksoniese, the former presents not 

 only a far greater variety in vegetative form, but also a much higher 

 differentiation of special structures. It will, therefore, be desirable 

 to consider the two tribes separately, though it is impossible in the 

 present paper to do more than indicate briefly some of the more typical 

 structural and vegetative features of each. 



LEAVES OF THE CYATHESE. 



The leaves of the Cyathete vary in length from 1 foot to 15 feet, the 

 two examples previously cited being AlsopMla Kuhnii and Cyathea 

 Brunei, respectively. In position they have been mentioned as arch- 

 ing in a semierect crown, spreading, or even drooping, their attach- 

 ment (in arborescent species) varying from nearly vertical to hori- 

 zontal, and thus determining, in connection with the rate of growth, 

 the shape, size, and relative position of the leaf scars. In addition 

 to the general shape and cutting of the leaf blades there remain now 

 to be noticed especially the thornlike armature of the stipes (leaf 

 stalks) and rachises (primary and secondary midribs of the blades), 

 the covering of the growing crown, and the production of minute scales 

 and hairs of many different kinds not only upon the vascular parts of 



