550 Filices—Nephrodium. 
forming a short stem above ground. Stipes short. Pinnules 
oblong, more or less toothed. Sori large, in one row on each 
side of the costa. There are several varieties, differing in the 
size and division of the frond and the quantity of chaffy scales 
on the stipes and rachis. MV. Bérreri, N. abbreviatum, N. 
affine, and N. cristutum, of Swartz, not of Richard, are forms of 
this species, in addition to which there are several crested and 
proliferous varieties in cultivation. A widely-dispersed species. 
N. cristatum differs from the foregoing in its flat, not 
convex indusium, and in the broad base of the pinnules; and 
N. rigidum in its mucronate rigid pinnules. Both are com- 
paratively rare in Britain. 
2. N. spinwlésum, including N. dilutatum, ete.—This is 
another common species, usually affecting moist shady situa- 
tions. It is a very variable plant in its extreme forms. The 
fronds are rather flaccid, dark green, bi- or tri-pinnate, on long 
slender stipes, and usually somewhat deltoid in outline. Pin- 
nules lobed to the rachis, furnished with awned teeth. <A native 
of Europe, Asia, North America, and North and South Africa. 
N. @mulum has a more triangular and divided concave 
frond, smelling strongly of hay. 
3. N. Thelypteris. Marsh Fern.—This is a delicate species 
with creeping rootstocks, lanceolate pinnate fronds about a foot 
or 18 inches, or even more high; pinne deeply pinnatifid; 
pinnules entire. Stipes equalling or exceeding the leafy part 
of the frond, very slender and nearly or quite naked. It grows 
in marshy and boggy places, and the fronds are only of short 
duration. Widely distributed. 
4. N. Oredpteris, syn. N. monténwm. Sweet Mountain 
Fern.—A handsome mountain species with tufted lanceolate 
pinnate fronds, pinne pinnatifid, glandular beneath, the lower 
more distant and gradually smaller; pinnules entire. Stipes 
short, scaly. A native of Europe and Western Asia. 
There are several handsome Japanese species of this genus 
belonging to the section Lastréa, as N. atratum, N. opdcum, 
and M. erythrosérum. 
11. POLYPODIUM. 
This genus is distinguished amongst hardy Ferns by its 
globose sori, destitute of an indusium or involucre. Rhizome 
creeping or tufted ; fronds simple, pinnatifid, or pinnate. Nearly 
400 species of widely different habit are collected under this name, 
