DESCRIPTIONS OF TPIE SPECIES 
269 
- M - * - * -*»%* Polypodieae. 
Genus 40. POLYPODIUM Linn. 
Sori separate, scattered or irregular, round or nearly round, 
without indusium. Fronds jointed to the rhizome. 
A very large genus, containing nearly 800 species. The 
earlier botanists included under Polypodium all ferns with 
round dorsal sori, whether they had an indusium or not; but 
since then the genus even as above restricted has been divided 
by some botanists into many genera, distinguished by the 
venation. 
Key to the species : 
§ Frond pinnatifid, pinnate or two-pinnatifid, or occasionally simple. 
154. P. parvulum. Fronds pinnate, half inch wide, naked or 
deciduously hairy. 
155. P.vulgare. Fronds without scales ; veins free. Fronds one 
to two inches wide, pinnate. 
1 56. P. polyftodioid.es. Frond clothed with peltate scales, pinnatifid 
or pinnate. 
157. P. ensiforme. Frond without scales, and with a line of large 
areolae on each side of the mid-rib, from which veinlets run to 
the margin, or again anastomose. The large areolae containing 
one free veinlet. Frond simple to pinnate, firm. 
158. P. fthymatodes. Frond without scales, veinlets anastomosing 
freely, and the larger areolae containing smaller areolae besides 
free veins. Frond simple to pinnatifid, large, thinly coriaceous. 
§§ Frond simple (except 162/3). 
159. P. lineare. Frond one-half to one foot long, without scales. 
Veins anastomosing freely and irregularly. Sori sunk, placed in 
a medial row on each side of the mid-rib. 
a. Frond herbaceous ; rhizome long. 
Var. / 3 . simplex. Frond larger, thinner, veins more distinct. 
Var. y. Schraderi. Frond small, coriaceous; rhizome short, 
tufted. 
160. P. Paftftei. Frond one to two feet long, without scales. Sori 
superficial, scattered, or sometimes in an irregular line near the 
mid-rib. 
1 6 1 . P. lanceolatum. Frond set with peltate scales, simple, lanceo- 
late. 
Var. / 3 . sinuatum. Frond sinuate or pinnatifid. 
