It does not appear that any other kind of fructification is described
hy botanists, except tlie sori, or line of spots on each side of
tlio midrib. The penetrating eye of Mrs Griffiths has, however, discovered
another, in which tlie wliole frond is covered with single scattered
seeds, similar to those of the sori,—a modification analogous
to what the same lady has observed in Dictyota dichotoma. This
twofold fructification differs from that of the F l o r i d e z e , in the circumstance
of both kinds consisting of similar seeds. The reticulation
of the frond in this genus is very conspicuous under the microscope,
and the cellules are arranged obliquely from the midrib to the
margin. Qn the surface of, at least, H. polypodioides are minute
pores, from which issue tufts of white filaments, as in some species of
Fucus,—a. fact sufficient to prove that this organ does not indicate
generic affinity.
Professor Sprengel, who, whatever may be the merits of his book
III other respects, has a singularly indefinite idea of the genera of many
Cryptogamic plants, has brought Dictyota dichotoma, with other species,
into this genus.
1. H a l y s e r is p o l y p o d io id e s . Tab. VIII.
Frond dichotomous, entire at the margin, obtuse at the apex, spots
of seeds linear-oblong forming a line on each side of the midrib.
S y s t. A lg . p . 262. S Haliseris polypodioides, Ag . S p . A lg . v . 1. p 142. p r e n g . S p . P I . v . 4.
p . 328.
Fucus polypodioides, L am o u r . D is s e r t, p . .32. t . 24. f . I .
Dictyopteris polypodioides, L am o u r . J o u r . B o t . p . 19, a c c o rd in g t o A g a rd h .
Dictyopteris elongata, L am o u r . E s s a i, p . 56, a c c o rd in g t o A g a rd h .
Fucus membranaceus, S ta c k h . N e r . B r i t . t. 6. T u r n . S y n . F u c . p . 141. H i s t . F u c . t. 87.
S m . E n g . B o t. 1. 1758.
H a b . In the sea, on rocks and the larger Algce. Biennial ? August
to October. Chit rocks, Sidmouth, and Peakhead rocks two miles to
the west of Sidmouth, Mrs Griffiths. St Austell’s Bay, Cornwall,
Mr W. Rasleigh. Shield’s Beach, Mr Winch. Near Torquay.
Root a spreading mass of woolly filaments. Fronds many from the
same base, eight to twelve inches or more in height, and about half an
inch in width, linear, several times dicbotomously branched, furnished
with a decided midrib, the surface more or less dotted with tufts of
white filaments issuing from minute pores, the extremities obtuse.
Fructification blackish ovate seeds, cither solitary and scattered
over the trond, or aggregated and forming oblong spots arranged on
each side, and nearly close to the midrib, in a linear series : the two
kinds always found on distinct individuals.
Substance between cartilaginous and membranaceous, somewhat
elastic when growing ; in drying it does not adhere to paper. Colour
pale, brownish, olive green, glossy, somewhat transparent.
Besides the two modifications of the fi-uctification which I have described,
another state of the plant has been observed by Mrs Griffiths,
which is evidently in some way or other connected with the fructification.
The appearance will be better understood by a glance at the
plate, than by description. That portion of the frond which is usually
occupied by seeds (about the upper half), is marked with dark,
waved, most irregular lines, inclosing spaces of various sizes, often confluent
and intersecting each other, and resembling the lines on a map
more than any thing else ; sometimes these lines are more scattered,
and then resemble little islands of all shapes. The spaces so inclosed
are somewhat more transparent, under the microscope, than the rest
of the frond. The lines themselves, when microscopically examined,
exhibit nothing that can lead to a knowledge of their real nature ; the
cellules of the part are sometimes filled with a dark mass of vegetable
matter, which is hardly definite enough to be called a granule ; the
cellules themselves are also sometimes distorted. Mrs Griffiths, who
communicated many specimens of the plant in this state, informs me
that the substance of the frond is thicker when fresh, than in barren
specimens. This appearance occurs on distinct individuals, and at the
period when other specimens produce seeds.
It not unfrequently happens that the frond appears to be proliferous
from the midrib. When carefully examined, it will be seen that the
young shoot does not actually proceed from the midrib, though it always
arises near it. It springs from an oval semi-opake green mass,
and, if the mass were a seed, we should say without hesitation that
young fronds were vegetating upon the old one. In Dictyota Kunthii
this is actually the case ; and in D. dentata there are also abundance
of little fi-onds springing from both surfaces. In H. polypodioides the
little fronds at length really attach themselves to the midrib, and generally,
in so doing, throw out a few woolly filaments like those of the
root of the parent plant.
The odour of this species when fresh gathered is extremely powerful
and disagreeable.
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