Aspidium.] 
FERNS. 
29 
4. — ASPIDIUM THELYPTERIS. 
MARSH SHIELD-FERN. 
(Plate 2, fig. 6.) 
Cha. — Frond pinnate, erect. Pinnae linear, lanceolate, smooth. 
Segments mucronated. Sori small. Root creeping. 
Syn. — Aspidium Thelypteris, Swz., Willd., Smith, Hook., Gulp., Mack., 
Pursh. — Polypodium Thelypteris, Linn., E. B., Dicks., Ehrh., With., 
Light f., (not of Huds.) -Acrostichum Thelypteris, Linn., Bolt . — - 
Athyrium Thelypteris, Spreng. — Polystichum Thelypteris, Both. 
Fig .—E. B. 1018.— Flo Dan. t. 760.— Bolt. 43, 44. 
Des. — Root creeping, furnished with long, black, slender, rather 
smooth runners, giving rise at various points along their surface to 
black radical fibres, and erect, light green, smooth, ovate, or (when 
fertile) oblong fronds, each from 6 to 12 inches long, having a 
slender, and generally smooth rachis. Pinnae linear-lanceolate, 
pointed, deeply pinnatifid, petioled, opposite. Segments oblong, 
obtuse, occasionally with a very small point ; the first upper segment 
on each pinna, much longer than the others. Sori in continued 
longitudinal lines near the margin of each segment, small, brown or 
black, at first distant, afterwards confluent. Cover thin, white, 
round, kidney-shaped, fastened near the centre, and soon lost among 
the growing thecae. The barren fronds differ much from those 
which are fertile ; they are altogether wider, shorter and flatter, 
with the pinnae horizontal, and rachis void of pinnae half way up. 
The fertile fronds have two-thirds of the rachis covered with pinnae, 
which are more numerous, deflexed, and cnrled, particularly at the 
point. The edges of the segments, bending over the lines of sori, 
give it an acute appearance. 
The only British Fern with which it is possible to confound this is Aspidium 
Oreopteris, from which it differs in its smaller size, lighter color, more ovate 
frond, not contracting so much below, the folded segments of the pinnae, and 
its creeping root. This last character will distinguish it from all our other 
species of this genus, it being the only one of which the root is not tufted. It 
is by no means easily cultivated, nor frequent in fruit when wild, as the fertile 
fronds do not rise till late in the season. While undergoing the process of 
desiccation for the Herbarium, the elasticity of the annulus of the theca is very 
apparent, bursting with violence, and scattering the spores in all directions 
and to a considerable distance. Sprengel says that the plant is glandulous, in 
which state Hudson describes it as Polypodium Fragrans. 
Hab. — Filby, Ormesby, &c., Norf., Mr. Paget. Learmouth Bogs, Northum., 
Mr. Winch. Allesley, Warw., Rev. W. Bree. Sussex, Mr. Borrer. Somer- 
set, Mr. Southing. Near Settle, Yorks., (scarce,) Mr. J. Tatham. Coxton 
Bogs, Notts., Dr. Howitt. Belton, Suffolk, Mr. Paget. Valley below Caesar’s 
Camp on Wimbledon Common, planted there some years ago by Mr. Tytom 
