GENERA AND SPECIES. I27 
PLATE XLIX. 
LYGODIUM. Swartz. 
GEN. CHAR.—Fruit-dots arranged on contracted pinnules of 
spike-like lobes, covered on one side by imbricate, hooded scales; 
fronds leafy, climbing. 
This remarkable genus differs very much from any yet 
described, both from its general appearance and the pecu- 
liar arrangement of its fruit-bearing apparatus. It belongs 
to the sub-order Schizzeacez, and is distinguished by its 
having the sporangia inclosed in the hooded scales of a 
two-ranked, imbricated spikelet. Figure 1 shows a portion 
of the fertile part of the frond magnified; a, the pinnules 
covered with imbricated scales (indusium); 4, with the 
scales removed, exposing the sporangia fixed to the veinlet; 
figure 2, a sporange magnified fifty diameters. 
It differs widely from all other ferns from the fact that it 
is a climbing plant. The species of this genus are mostly 
confined to the warmer regions of the globe, although the 
only one found in this country is able to endure the ex- 
treme cold of a New England winter. Four fossil species 
of Lygodium are described by Mr. Lesquereux from the 
tertiary, and one from the cretaceous deposits of the West.* 
Though these specimens are mere fragments of leaves, the 
peculiar nervation is well preserved, and is quite sufficient 
to identify the genus. 
* See ‘‘Cretaceous Flora of the West. Territories,’”’ p. 45, plate i, 
figure 2; also, ‘‘ Tertiary Flora,” p. 61, plate v, figures 4-9. 
