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 Cyatheacex, 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 leafiness 
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 such a vast bigness, which in Europe were 
so 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 calls 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 Cyatheacee. 
ARBORESCENT HABIT. 
A typical group of tree ferns of different ages is shown in plate 1, 
a scene in Guatemala. The species is Cyathea princeps (often known 
as C. Bourgaei, and described more recently as C. Munchit), 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 (pl. 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 
