316 THE BRITISH FERNS. 
terminal and adherent to the caudex. Secondary rachides channelled 
and margined in front. i 
Fronds numerous, erect or sometimes arching, variable in height : 
two to four feet in dryish exposed localities, six to eight or even 
occasionally ten to twelve feet in very damp sheltered spots; mem- 
branaceous, smooth, bright yellow-green, paler beneath, broadly- 
lanceolate, bipinnate, occasionally tripinnate. Some of the fronds 
are entirely barren, while others have several of the upper pinnæ 
transformed into a terminal fertile panicle. Pinne (sterile) nearly 
opposite, lanceolate or ovate-lanceolate, impari-pinnate, distant. 
Pinnules opposite or alternate, one to two and a half inches long, 
sessile, oblong or oblong-ovate, obtuse, sometimes slightly falcate, 
rounded or somewhat dilated at the base especially on the posterior 
side, sometimes distinctly auricled, occasionally deeply lobed or sub- 
pinnate ; the terminal ones, which are more acute than the rest, 
are usually lobed at the base; the margins are obscurely crenated, 
or sometimes serrated. 
Venation of the sterile pinnules consisting of a stout costa or mid- 
vein giving off nearly opposite veins, which are forked once near their 
base, the venules being parallel, slightly curved, and once or twice 
forked before reaching the margin in which they are lost. 
Fructification consisting of the upper pinne (usually wholly, some- 
times only in part) changed into a bipinnated panicle of contracted 
rachiform capsuliferous divisions. Each short spike-like branch of 
this panicle represents one of the pinnules, the spore-cases being 
collected on it into- little more or less evident nodules, and the 
nodules corresponding to the fascicles of the veins. "This becomes at 
once evident in the case of partially transformed pinnules. Spore- 
cases subglobose, reddish-brown, reticulated, shortly-stalked, two- 
valved, opening vertically. Spores smoothish, globose or oblong 
with a central depression, yellowish. 
Duration. The caudex is perennial. The fronds are annual, 
growing up very rapidly early in May. The panicles reach maturity 
early in summer and soon decay, and the fronds themselves are 
destroyed by the autumnal frosts. 
This, the most stately of the British Ferns, is well deserving the 

