I m l
bright lierbacrous green—fading in age, or, when exposed in shallow
water to much sun, to a delicate pale yellowisli-green or greenish-
white, and then becoming also semitransparent. In drying, it adheres
more or less to paper, and does not change colour.
In his “ Species Algarum,” Agardh expresses his doubts whether
this be a really distinct species ; but after a careful investigation, I am
led to an opposite result. Neither can I follow the same author in
placing it among the Solenioe (my Enteromorphoe) ; for the habit is
altogether that of a true Viva ; and the structure, though more obscure,
accords better with the Vlvoe, as does also the fructification.
It must be confessed, at the same time, that the plant is peculiar in
having the frond composed of two membranes, so closely united as to
appear like a single one. In this respect, it certainly seems to approach
near to Enteromorpha intestinalis and compressa, with which
Agardh has associated it. I have never, however, seen it really
tubular.
* * Species found in fre sh water.
4. U l v a b u l l o s a .
Frond obovate saccate gelatinous at length irregularly expanded
floating waved and búllate.
XJlva hullosa, R o th . C a t . B o t. v . 3. p . 329. A g . S p . A lg . v . 1. p . 414. S y s t. A lg . p . 190.
S m . E n g . B o t. t . 2320. S p r e n g . S p . P I . v . 4. p . 368.
Viva Lactuca, v a r . /3, H u d s . F I . A n g l. p . 567- L ig h t f . F I . S c o t. p . 971.
H a b . In fresh water pools and ditches. Annual. Spring and summer.
In the Meadows, behind Newington, Dillenius. Henfield, in
Sussex, Mr W. Borrer. In Scotland, Lighfoot. Ditch surrounding
Duddingston Loch, near Fdinburgh.
Fronds aggregated, fixed in their young state, obovate and tubular,
one to five inches long, soon lacerating and expanding into a plane
membrane, which detaches itself and floats on the surface of the water.
At this period it is very irregular in form, waved, and distended with
air-buhbles. Fructif cation, quaternate granules scattered over the
whole frond. Substance excessively tender, thin, and gelatinous.
Colour a fine pale green, yellowish in age- In drying, it adheres most
closely to paper.
There can he no difficulty in recognizing this very distinct species,
growing, as it invariably does, in fresh and mostly stagnant water.
Wlien seen floating on the surface of the water, it retains the air that
happens to be disengaged beneath it, and has all the appearance, as
Lightfoot has observed, of being in a state of fermentation. The frond
is infinitely more tender and gelatinous than the preceding species,
and can hardly be held in the hand without breaking into pieces and
slipping through the fingers.
This plant may be regarded as intermediate between Viva and the
genus Tetraspora of Link, adopted by Agardh, in his Systema Alga-
lum, for Ulva lubrica of Roth, Ulva cylindrica of Wahlenberg, and
Ulva gelatinosa of Vaucher. The discovery of all these in this country
may he anticipated.
# * # Species found on damp ground, walls and rocks.
5. U l v a c r is p a .
Fronds crowded deep green rounded inflated much wrinkled and
folded.
Ulva crispa, L ig h t f . F I . S c o t. p . 972- Ag . S p . A lg . v . 1. p . 416. S y s t . A lg . p . 190.
G r e v . F I . E d in . p . 299. S p r e n g . S p . P I . v . 4. p . 366.
Ulva terrestris, R o th . C a t. B o t. v . 1. p . 211.
Viva Lactuca, v a r . 7 , H u d s . F I. A n g . p . 567-
Tremella terrestris. D i l l . H i s t . M u s e . p . 62. t . 10. f . 12.
H a b . On damp ground in shady places, near houses and walls, and
on old thatched roofs. Annual. Winter and spring. Common.
Fronds not an inch in height, lying on the surface of the ground,
without any apparent root, and forming a crowded stratum; inflated,
folded and wrinkled. Fructification, quaternate granules beautifully,
arranged so as to form parallel lines—and those lines, again, squares
with vacant intervals between them. Substance very thin, and rather
tender, but not gelatinous. Colour a dark green. In drying, it does
not adhere to paper.
A plant of no beauty, with somewhat of the habit of Tremella, for
a species of which it was taken by Schreber and Willdenow. Agardh
compares the an-angement of the fructification to the walks and parterres
of a garden. It is singular that no British figure should exist of
this vegetable, except the very indifferent one of Dillenius. ■
It
4» '
V il
■;i' ‘-si .
7iP
(i.%.
Jg-r.