474 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



Jenman cites Alsophila armata and Cyathea furfuracea in Jamaica as 

 occasionally branched and having two or more crowns, and Alsophila 

 aspera as having produced in one instance several stems from a 

 single base. The peculiar Bicksonia Berteroana of Juan Fernandez 

 is said to divide at the base, having branches up to 18 feet long and 

 "thick as one's leg." A notable instance also is that of a New 

 Zealand species, Hemitelia Smithii, as described and figured by 

 Buchanon, in which a specimen 16 feet high had no less than 16 

 branches. In AlsopTiila quadripinnata, previously mentioned, the 

 branching is at or near the ground, as in Bicksonia Berteroana. 



Christ has also mentioned on Werckle's authority a remarkable 

 example of adventitious growth in a Costa Rican tree fern (Cyathea 

 sp.) which is worthy of further investigation. In this plant buds are 

 said to have been borne in all the axils of the leaves, their position 

 therefore being at the upper side of the leaf scar after the fronds were 

 fallen from the trunk. Although a comparatively small number of 

 these developed, yet the stem was several times branched at a height 

 of 5 feet, and the larger of the branches formed a beautiful crown of 

 more than 25 branches. 



In a large number of Cyatheaceae having treelike stems one of the 

 most conspicuous features is the development of adventitious roots, 

 which encircle the older portions of the trunk in a hard, wiry, closely 

 interwoven mass, very much like bark. These roots are commonly 

 produced in great abundance, often wholly obscuring the original 

 proportions of the stem, which may, indeed, appear in cross section 

 merely as a core, measuring but one-fourth to one-half the total 

 diameter. Toward the bottom of the trunk they are especially 

 abundant, as might be expected, and frequently occur in such quan- 

 tity as to form a massive conical base, which undoubtedly serves to 

 give stability to the lofty stem, as in Cyathea suprastrigosa (C. con- 

 spicua), a species inhabiting the upper slopes of several Costa Rican 

 volcanoes, whose huge base is said to measure a full 5 feet in diame- 

 ter. There can be little doubt also that the formation of the dense 

 indurated covering of the lower and middle portions of the trunk 

 proper gives great strength and rigidity to the otherwise slender 

 stem, which better enable it to support the weight of the upper 

 part, including the great spreading crown of succulent leaves. The 

 production of these aerial roots is apparently continuous, the diame- 

 ter of the complete "trunk" (stem and aerial roots combined) thus 

 roughly keeping pace with the elongation of the trunk. 



Tree fern trunks of this sort are the favorite home of many filmy 

 ferns (Hymenophyllaceee) , a few of which, like Trichomanes capil- 

 laceum (T. trichoideum) , are not often found in other places. The 

 sight of a huge fern trunk, its rough surface clothed on all sides in a 

 lacelike mantle of this most delicate of all ferns, each of their hair- 



