464 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 



From this description, brief as it is, several of the most character- 

 istic features of the group as a whole may be noted: The single and 

 simple unbranched trunk or stem, "after the manner of palm trees," 

 the spreading circular crown of ample fronds surmounting the stem, 

 the lighter color of the under surface of the leaf, which may be 

 observed in nearly all Cyatheacese, not a few of the species being 

 grayish or even whitish below, and above all the "close-set" divisions, 

 without "defect or empty space between them," a feature which in 

 connection with the enormous size of the fronds of many species 

 lends to tree ferns their greatest charm, that of surpassing leanness 

 and vigor. 



For the benefit of the ignorant or of the superficially minded 

 Sloane adds: 



From these Trees growing on the Mountains of Hispaniola the Spaniards argued the 

 fertility of that Soil, making Ferns grow to Buch a vast bigness, which in Europe were 

 bo inconsiderable, not considering that the Ferns in Europe and here, were quite 

 different kinds one from the other. 



Not alone in dimensions, but also in technical characters of struc- 

 ture are the huge ferns of this alliance distinct from those of conti- 

 nental Europe. Sloane cafis them "trees," and to this day the term 

 "fern tree" is employed in Australia as commonly as our more 

 familiar "tree fern" for members of the Cyatheacese. "Fern-tree 

 gullies" is there a common expression, applied to deep shady ravines 

 of the moister coastal regions having a dense growth of Cyatheacese. 



ARBORESCENT HABIT. 



A typical group of tree ferns of different ages is shown in plate 1, 

 a scene in Guatemala. The species is Cyathea princcps (often known 

 as C. Bourgaei, and described more recently as C. Munclrii) , a rather 

 uncommon plant which ranges from the moister parts of Mexico to 

 Alta Verapaz, eastern Guatemala. Not all species of Cyathea have 

 their fronds so rigidly ascending. Indeed, Cyathea arborea, which 

 is the commonest and perhaps the most graceful North American 

 member of the genus, will be seen (pi. 2) to have them laxly arching 

 or even drooping. The direction of the fronds, however, in many 

 species depends much upon the age of the plant. Thus, the smaller 

 individual at the right in plate 1 owes the upright position of its 

 fronds in part to its quick, vigorous growth and partly, no doubt, to 

 the need the plant has of stretching its leaves up toward the level 

 of the rather dense surrounding undergrowth, where of course the 

 sunlight is much stronger than below. 



Tree ferns may in fact be regarded as "standing on tiptoe" in 

 their effort to secure light and air. They are commonest in those 

 moist, densely forested, tropical regions where their struggle for 



