THE COMMON MAIDENHAIR FERN. 247 
Fronds usually ovate or triangular, sometimes oblong or lanceo- 
late, membranaceous, glabrous, bright green, drooping, from six to 
twelve or sometimes eighteen inches in length, bipinnate or tri- 
pinnate. Pinne and Pinnules alternate; the latter attached by 
short capillary stalks, of various forms: roundish with the base 
truncate, subtrapeziform, obovate or obliquely fan-shaped, generally 
more or less cuneate at the base, the posterior margins entire, the 
anterior lobate. In the sterile fronds the lobes are dentate or inciso- 
dentate; in the fertile ones they are obtuse or truncate, the sori 
often occupying their entire width. 
Venation of the pinnules consisting of a series of dichotomous 
ramifications of the vascular bundles of the petioles, the first furca- 
tion forming the extreme base of the pinnule; the veins are again 
and again forked in a flabellate-radiate manner, so that the whole 
pinnule becomes traversed by a series of contiguous and nearly 
parallel venules, which are disunited at their apices. In the sterile 
portions, one of these venules is directed to each marginal tooth, in 
the apex of which it terminates; whilst in the fertile portions, the 
venules extend to the margin, and being continued thence nearly 
across the indusium, there form the receptacles. 
Fructification generally distributed on the back of the fronds. 
Sori oblong, borne on the apices of all the lobes into which the 
anterior margin of the pinnule is divided, more or less lengthened 
according to the width of the lobe; attached to the under surface 
of the indusium. Jndusium of the same form as the sorus, con- 
sisting as it were, of a portion of the apex of the lobe, reflexed, and 
changed in texture into a thin bleached veiny membrane, the veins 
being the receptacles. Spore-cases globose. Spores roundish or 
angular, ovate, smooth. 
Duration. The rhizome is perennial. The fronds are persistent, 
remaining until after young ones are produced, if kept from being 
injured by frost. The young growth commences in April or May. 
This is unlike every other British Fern ; its black shining slender 
stipites, its capillary ramifications, and its fan-shaped or wedge- 
shaped pinnules, irrespective of its fructification, serve at once to 
distinguish it. i 




