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AS P L ENIUM Ruta-muraria.
White Maiden-hair or Wall-rue.
C R T P T O G A M I J Filiecs.
Gen. Char. Fructifications in fcattered lines, Invo-
lucrum originating laterally from a vein, and burft-
ing inwardly (that is towards the nerve). Smith
Mem. of the Turin Acad. Vol. 3.
S pec. Char. Frond alternately twice compound j
leaflets wedge-fhaped notched.
Sy n . Afplenium Ruta-muraria. Linn. Sp. PI. 1541.
FLudJ. FI. An. 4 5 3 . With. Bot. Arr. V. 3. 53..
Relh. Cant. 3 8 9 .
Ruta muraria. Rail Syn. 122.
O l d walls and {hqdy rocks produce this little fern not un-
frequently, varying much in fize according to the degree of
nourifhment, or rather moifture, that it meets with. The
fruftifications may be found early in fummer in the beft ftate
for examination, when the membrane which covers each line
is about to burft. The genera of ferns can only be determined
in that early ftate, as many whofe involucra are widely different
have the back of their fronds covered in an advanced ftate with
one confufed mafs of capfules, and have hence been errone-
oufly referred to the genus of Acroftichum, as even the plant
before us might be if only feen in fuch a ftate. This is not one
of the moft eafy to be determined in any ftate, but if carefully
examined it will be found that the membrane always
burfts towards an adjoining vein or nerve, and never towards
the margin of the leaf without an intervening vein.
The root is perennial, of many dark thready fibres. Stalks
upright. Fronds thick and rigid, a little inclined, of a dark
glaucous green, fmooth in every part. Involucrum notched
in the margin.