129 
ON THE ASPLENIUM ADIANTUM-NIGRUM, var. OBTUSUM 
(SERPENTINI), AS A BRITISH PLANT. 
By Tuomas Moors, F.L.S., F.R.H.S. 
(Piate XVIL) 
Since the time of Willdenow, the existence in Europe of an Asplenium 
somewhat intermediate in characterand aspect between 4. Adiantum- , 
nigrum aud A. montanum, has been known. This Fern was called 4. 
obtusum by Willdenow himself, 4. Forsteri by Sadler, and 4. Serpentini 
by Tausch, but is now considered as a form or subspecies referable to 
A. Adiantum-nigrum, including a goodly array of synonyms besides 
those just mentioned. In the ‘ Index Filicum’ the name of 4. Adian- 
tum-nigrum, y. obtusum, is employed; but some authors, as Heufler 
and Milde, prefer that of A: 4.-Serpentini or A. A.-serpentinum. 
This Aspleninm Serpentini belongs to the triangular, tripinnate series 
of Aspleniums, and though varying much in the size and breadth of its 
parts, is rather small-pinnuled in its most marked and characteristic 
states. It has the pinnae straight and spreading, as compared with 
those of the variety or subspecies acutum, in which they are connivent ; 
-and from the more typical forms of Adiantum-nigrum, which have the 
base of the segments incurved, it differs, according to Heufler, in having 
the base of the segments recurvate. In some ofits forms the segments are 
blunt and firm, in others blunt and of thinner texture, aud in others 
again more or less acute even ; but those forms which are narrow and ob- 
tuse, thus acquiring a wedge-shaped outline, are often acutely toothed 
at the apex. In outline, the pinnules vary from ovate-obtuse to ovate- 
acute or even almost acuminate, the segments in the former case hav- 
ing a short broad-ovate or ovate-oblong figure, and in the latter ap- 
proaching more or less nearly to linear, but without any of the peculiar 
features of acutum, in which the segments are more strictly linear. 
The surface is of a dull opaque green, not lucid, as in acutum, and the 
fructification is crowded and generally becomes confluent. 
Till recently, this plant was chiefly known as a native of Croatia, 
Dalmatia, Hungary, Bohemia, and Saxony, extending to Italy and pro- 
bably also to South Africa and Abyssinia. The name Serpentini was 
given to it from its being found on serpentine rocks. When, there- 
VOL. II. [May 1, 1864.] K 
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