THE TREE FERNS OF NORTH AMERICA. 



[With 15 plates.] 



By William 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 Cyatheaceae, 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 Cyatheacese 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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