VII. LASTREA. 99 
six to eighteen inches 'or more in height, smooth, delicate, 
almost membranous, pale green, lateral, and adherent to the 
caudex. The stipes is slender and smooth. The fronds are 
lanceolate scarcely narrowed at the base, pinnate. The 
pinna3 are often opposite, but sometimes alternate, distant, 
slightly drooping, the longest one and a half to three inches 
long, all ] linn. -it it'n I. with crowded entire oblong rounded 
lobes. The fertile fronds are similar to the barren ones, 
but taller and more robust ; sometimes upwards of three 
feet high, with distant alternate pinna; occupying the 
upper third of the frond. These fertile fronds have the 
margin of their lobes revolute, and this gives the latter the 
appearance of being narrower and more pointed than those 
of the barren fronds. The midvein of the lobes is distinct, 
and somewhat sinuous, producing free alternate venules, 
which are usually forked near the mid-vein, with the 
branches continued to the margin. In weak specimens 
some of the veins are simple, and in luxuriant ones they 
sometimes have more than two branches. Each branch 
usually bears at about hajf way between the margin and 
mid-vein a small roundish sorus, which hi its earlier stages 
is covered by a thin white reniform indusium, soon becom- 
ing pushed aside and lost The sori thus form a submar- 
ginal line, and finally become confluent, or nearly so, 
and are partially covered by the reflected margin of the 
lobe. 
This species is rare and local, though widely dispersed. 
It is only found in boggy and marshy places, and when 
present is generally abundant, being a free grower, and 
rapidly extending itself by its long creeping caudex. It 
occurs all over England and Wales and in all the Irish 
provinces, but in Scotland it is uncommon. It is found 
throughout Europe, and both ha Asia, Africa, and America. 
This fern grows freely under pot-cultivation if planted 
in wide pots, and hi turfy peat soil mixed with decaying 
tree leaves, and kept in a moist state; though it does not 
very freely produce its fertile fronds whea thus grown. 
