ray’s woodsia. 
141 
as to this species being distinct from TV. alpina ( W, hyperhorea of 
Smith) will again be noticed under my description of that species. 
With regard to the genus to which these little plants are 
referrible, considerable difference of opinion appears to pre- 
vail. Linneus, Bolton, Liljeblad, and Hudson, place them 
in the genus Acrostichum : Withering, Sowerby, Willdenow, 
Sprengel, Schkuhr, Wahlenberg, and Presl, in the genus Poly- 
podium ; Lamarck and Decandolle in the genus Ceterach : 
Smith, Hooker, Sadler, and Babington, in the genus Woodsia, 
instituted by Dr. Robert Brown purposely to receive them. The 
description of this genus was published in the eleventh volume 
of the Linnean Transactions,* and its distinguishing character 
consists in the peculiar structure of the involucre, which is in- 
serted under the cluster of capsules, the attachment of which it 
surrounds, while its margin, as in the linear involucre of Pteris, 
already described, is split into a number of jointed capillary 
segments, which intermingle with the capsules, partially con- 
cealing them.f 
The roots are black, wiry, and sparingly branched : the rhi- 
zoma thick, tufted, and lasting many years : the stem is very 
distinctly jointed at a distance of three quarters of an inch from 
its junction with the rhizoma ; the articulation is swollen, 
and very obvious to the naked eye when the frond is mature ; 
at this point, as far as my observation has extended, separation 
generally takes place, the basal portion of each stem adhering 
to the rhizoma. This very interesting character, common to all 
plants of this genus, is well described by Wahlenberg, J whose 
observations I have quoted under my next species. The stem 
above this joint, and between the pinnae, is clothed with lance- 
olate scales, and shining jointed hairs : the form of the frond is 
lanceolate and pinnate : the pinnae are in pairs, and generally 
opposite, oblong, obtuse, deeply lobed, and in some specimens 
pinnatifid, in which case the lobes are crenate, as in figure c. 
The upper surface of the frond appears quite smooth to the 
naked eye, but under a lens of high power, a few long bristle- 
* Trans. Linn. Soc. xi. 170. 
X Flor. Lapp. 279. 
f See Appendix D. 
