




120 THE BRITISH FERNS. 
the base, green in the upper part; terminal, and adherent to the 
caudex. Rachis smooth, green. 
Fronds one to six inches long, numerous, deep green, more or 
less coriaceous, deltoid, bi-tri-pinnate; in the young or juvenile state 
simple and reniform, or trifoliately pinnate with roundish or sub- 
reniform leaflets, these trifoliate fronds often fertile. Pinne 
alternate. Pinnules obovate or rhomboidal, the base wedge-shaped 
entire and tapering into a more or less distinct petiole, the apex 
rounded or truncate or sometimes acutely prolonged always toothed, 
the teeth small and nearly equal. 
Venation consisting of a series of veins repeatedly forked from the 
base, so that there is no distinct costa or midvein; the number of 
the branches or venules which are developed correspond with the 
number of marginal teeth. 
Fructification on the back of the frond, borne on the inner sides 
of the venules about the centre of the pinne. Sori linear, few, ` 
sometimes simulating those of Scolopendrium: being contiguous 
nearly opposite and opening inwardly from each margin; often 
becoming confluent, especially when the plants are starved, in which 
condition they produce small pinnules and abundant sori confluent 
over the whole under surface. Indusium, a thin narrow membrane, 
having the free margin wavy or crenulate. Spore-cases dark brown, 
numerous, roundish, obovate, coarsely reticulate. Spores roundish, 
strongly muriculate. 
Duration. The caudex is perennial. The fronds are produced in 
spring, and retained through the winter, until after fresh ones appear, 
so that the plant is evergreen. 
In its usual condition this species is easily recognised; the cha- 
racters afforded by the deltoid outline, bipinnate or tripinnate 
division, and distinct cuneate pinnules, taken together with the 
small size of the fronds, sufficiently distinguishing it from the other 
Aspleniums. There are, however, certain forms of the species which 
are not at first sight easily separated from A. germanicum, being 
narrow in the fronds or pinnules, and sometimes scarcely more than 
pinnate. These states are best distinguished by the crenulate 
indusium, and by the fine even toothing of the anterior margin ; the 

