THE TREE FERNS OF NORTH AMERICA. 
[With 15 plates.] 
By Witr1am R. Maxon. 
Although the name tree fern is occasionally given to any large 
fern of treelike form, it has come by common usage to have a definite 
application to the members of a single family, the Cyatheacex, and 
in so far as any one descriptive term can apply to a large group of 
world-wide distribution, whose distinctive technical characters are 
minute and not always very obvious, the expression is a singularly 
appropriate one. The Cyatheacez are known as tree ferns because 
the great majority of the species are essentially treelike in size and 
proportion and have strong woody trunks, often attaining a height 
of 40 feet or more. : 
One may easily imagine the feeling of surprise with which the 
early voyagers to the New World, looking upon the wonderful pro- 
fusion and luxuriance of these enormous plants, contrasted them 
with the relatively small ferns of Europe. One wonders also at the 
restraint and rather passive scientific attitude of Sloane, one of the 
earlier English writers upon the West Indian flora, who, having 
accompanied the Duke of Albemarle upon his voyage to Jamaica in 
1689, thus quaintly describes a common species (Alsophila aspera), 
as he observed it in that island: 
This has a trunc twenty Foot high, as big as ones Leg, (after the manner of Palm- 
trees) undivided, and covered with the remaining ends of the Foot-Stalks, of the 
Leaves fallen off, which are dark brown, as big as ones Finger, two or three inches 
long, thick set with short and sharp prickles. At the top of the trunc stand round 
about five or six Leaves, about six Foot long, having a purple Foot-Stalk, very thick 
beset with short, sharp prickles on its backside. At about a Foot distance from the 
Trunc, each Leaf is divided into Branches set opposite to one another, placed near 
the bottom, at about six Inches distance from each other. 
The ultimate divisions (segments) of the leaf are mentioned as 
about one third of an Inch long, and half as broad, blunt, easily indented about the 
edges, of a dark green colour above, pale green below, very thin, and so close set to 
one another that there is no defect or empty space between them. 
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