There are few more beautiful plants among the filiform Algae
of our coasts, and not many more rare than the subject of this
plate, which, though found in several distant localities is no
where abundant in Britain. It is, indeed, a species of the south
of Europe which finds its northern limit in our seas, where it
does not reach much more than half the size that it attains in
the Mediterranean. Specimens from the shores of Italy are
nearly as large and bushy as S. scoparia, but much more slender in
all their parts. Our British individuals, except those from Jersey,
are so feeble, and have so different an aspect, that Dr. Greville,
who first figured them in his beautiful Cryptogamic Flora, regards
them as belonging to a different and peculiar species, which he calls
/S', hypnoides. A careful comparison with numerous continental
specimens from various quarters has led me to an opposite conclusion,
the differences appearing to me to be merely such as may
be fairly referred to climate. The Mediterranean specimens of
Grateloupia filicina are quite as unlike the British ones as those
of the Mediterranean Sphacelaria filicina are to ours. There is
no difference in the microscopic characters of the ramuli, or in
their disposition, if the specimens have respectively been collected
at the same season. Between the winter and summer states of
this species, however, the differences are so great, that Agardh
formerly constituted them two species, his 8 . simpliciuscula,
which has its pinnules subsimple, being the winter state of
8. filicina. A similar difierence between the summer and winter
appearance of 8. scoparia has already been pointed out. Indeed,
so great is the variableness of aspect which specimens at different
ages present, among the 8placelaria;, that, as Meneghini well
remarks, the greatest caution should he exercised by authors
who propose new species ; and the plants should be watched in
their place of growth from their first appearance to maturity.
But this is often no easy matter, especially with such rare plants
as the present. Since our plate has been prepared Miss Turner
has communicated from Jersey a magnificent specimen,2fully as
large as one from the south of Europe, and covered with fructification.
I regret that it is too late to add a representation of
the spore to the analysis already given.
Fig. ] . S p h a c e l a r i a f i l i c i n a :— the natural size.
4. Cross section of the stem.
A branch. 3. A pinna.