186 
ASPIDIACEvE. 
tr(Ba ; Schott constitutes a genus [Thelypteris) purposely to re- 
ceive it, and gives to the species the name of palustris ; and Sir 
W. J. Hooker, in the fifth edition of his ‘ British Flora,’ makes 
it an Aspidium : thus we have three of the highest, as well as 
most recent authorities, completely at issue on the question. 
The roots are black and fibrous ; the rhizoma slender, black, 
and rapidly creeping. The fronds are of two kinds, barren and 
fertile ; the barren appear in May, the fertile in July : the pin- 
nules of the young frond stand out at right angles with the stem. 
The stalk of the barren frond is long, smooth and erect ; the 
frond lanceolate and pinnate ; the lowermost pinnae are rather 
shorter than the second, third or fourth pairs, still not materially 
shorter, and always situate a long distance from the base of the 
stem : the pinnae are generally nearly opposite, distant, linear, 
slightly drooping and pinnatifid ; the pinnules crowded, entire 
and rounded at the extremity ; the habit is slender, delicate, and 
very fragile ; the texture thin and almost membranaceous ; the 
colour pale green. The fertile frond differs in being much more 
tall and robust and in having the margins of the pinnules con- 
volute, and the pinnules themselves are thus rendered narrower 
and apparently more distant. 
The lateral veins of the pinnules are al- 
ternate ; they are forked almost immediately 
on leaving the mid-vein, and each branch 
proceeds to the margin of the pinnule (as 
shewn at page 183), bearing a nearly circular 
cluster of capsules about midway between 
the mid-vein and margin : at the back of 
each cluster, in an early stage of the frond, 
may be seen a small, flat, whitish, reniform 
involucre, as represented in the figure in the 
margin ; this soon withers, is pushed aside 
by the swelling capsules, and is lost : the 
clusters of capsules become confluent, and 
the semi-bleached semi-membranous margin of the pinnule 
partially covers them. 
