470 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



numbers being from 20 to 30 feet high; the usual shape of the trunk 

 was cylindrical, although many showed a conical form at the enlarged 

 base. Among North American species the largest known is Cyathea 

 Brunei, as it occurs on the lower slopes of the Volcano Turrialba in 

 Costa Rica. The trunk of this is nearly cylindrical and very stout, 

 12 to 15 feet high, 12 to 20 inches in diameter, and clothed with the 

 dead hanging fronds of previous seasons; the fronds measure 12 to 15 

 feet long and 5 to 6 feet broad — truly a giant among ferns. 



It is interesting to note, however, that in addition to the two very 

 small American species previously mentioned a fair number of Cya- 

 theacese have failed to develop a pronounced upright habit, and that 

 several of these are among the largest-fronded species of the family; 

 for instance, Alsophila quadripinnata (A. pruinata) and several species 

 of Hemitelia, section Cnemidaria. The former, which in one state or 

 another ranges through the West Indies and from Mexico to Chile, 

 has enormous fronds, 9 to 15 feet long, borne in a spreading crown 

 from a short erect stem which is rarely more than 3 feet high and 

 usually much less, averaging perhaps 1 foot high, with a diameter of 

 3 to 5 inches. Jenman has called attention to the fact that the stem 

 of this commonly "buds and throws up from the base a number of 

 minor stems about half the size of the primary one," a condition 

 which is comparable to the development of the fasciculate or multi- 

 cipital crown in the male fern (Dryopterisjilix-mas) and other common 

 northern species, but which is not found in many Cyatheaceae. The 

 Cnemidaria species mentioned show a wide amount of variation in 

 length of trunk. One or two South American members of this small 

 and exceedingly interesting section have tall slender trunks, but most 

 of the North American representatives have the stem either short (1 

 to 3 feet high), thick, and erect, as in Hemitelia (Cnemidaria) horrida 

 (pi. 11), or a little longer, and weakly ascending, rarely attaining the 

 dignity of a trunk. 



TYPES OF UPRIGHT TRUNKS. 



Two main types of upright trunks may be distinguished readily 

 among the American Cyatheacese: The first, in which the fronds, like 

 those of Cyathea arborea, fall completely from the trunk in old age, 

 leaving clean-cut scars; a second type, in which the fronds are imper- 

 fectly jointed to the trunk and thus are slowly deciduous, commonly 

 hanging for several years after dying, and even when fallen leaving 

 parts of their bases as a rough outer covering to the trunk. More 

 species have trunks of the first sort than of the second; but the latter 

 condition is not at all uncommon, and is apparently the rule for species 

 of Dicksonia. It is common also to many species of Cyathea, among 

 which may be mentioned C. nigrescens in Jamaica and C. araneosa in 

 Cuba. Some species are intermediate in this respect; and many (e. g., 



