CHARACTERS OF TRIBES AND GENERA. 351 
203,—Lyeoprum,. Sw. (1800). 
Hook. Syn. Fil. 
Vernation uniserial, distant and sarmentose, or contiguous 
and ewspitose. Fronds scandent, twining, extending to an 
indefinite length ; pinn; conjugate, palmate lobed, pinna- 
tifid or pinnate. Veins forked, free. ^ Sporangiferous 
spikelets marginal, composed of two rows of imbricate 
indussform cysts, each cyst containing an oval, resupinate 
sporangium attached by its inner side, and opening length- 
wise on its outer side. 
Type. Lygodium circinatum, Sw. 
Ilust. Hook, and Bauer, Gen. Fil., t. 28; Moore, Ind. 
. Fil, p. 90 B. ; J. Sm., Ferns, Brit. and For, fig. 141; 
Hook., Syn. Fil., t. 9, fig. 68, a, b, d. 
Oss.—The Ferns constituting this genus are readily 
known from all others by their climbing habit; the fronds 
being permanent, and increasing in length indefinitely by 
their twining and interlacing with one another, and with 
other plants, they form impervious thickets. The various 
forms they assume, and the divisions of the fronds, render 
it difficult to arrive at any satisfactory conclusion as to the 
number of distinct species. Presl enumerates forty species, 
but in the * Synopsis Filicum ” only sixteen are described, 
` which I consider to be nearer the true number of distinct 
‘species. They abound within the tropics, and extend to 
New Zealand in the southern, and L. palmatwm extends to 
. Canada in the northern hemisphere. 
* Petiole of pinnules articulate with the rachis. 
Sp. L. articulatum, Rich. (v v.) ; L. scandens, Sw. (v v); 
.. L, venustum, Sw. ; L. volubile, Sw. ; L. pinnatifidum, Sw. 
.. L. polystachyum, Wall. (v v.). 
