ovate, sometimes obovate, attached by means of little partial stalks to
the side of a horn-like common stalk or receptacle : in general one
pair of opposite vesicles is present ; there are, however, sometimes two
pair on the same common stalk, sometimes only a solitary vesicle :
the summit of the common stalk is curled, often reflexed. Substance
membranaceous, somewhat tenacious. Colour a rather light gi-een.
A well marked species. It once existed in a tub of water in the
old Botanic Garden of Edinburgh.
Hooker, in his Flora Scotica, has referred Dillwyn’s Conferva amphibia
to Vaucheria ornithocephala, but tlie figure given hy Dillwyn is
very characteristic, and, though destitute of fructification, accords entirely
with our plant, as does also the description.
It is suggested by Agardh, that this species may be only a variety
of V. 'Dillwynii, modified by situation : in confirmation of this opinion,
he mentions that be has occasionally observed in that plant terminal
pairs of vesicles, precisely similar to those of V. cæspitosa.
'Í
7. V a u c h e r ia cæ s p it o s a .
Fronds subdichotomous forming dense spongy masses, vesicles in
terminal pairs, the summit of the branch projecting beyond them.
Vaucheria cæspitosa, Ag . L y n g b . H y d r o p h . D a n . p . 81. t . 23. H o o k . F l . S c o t. P t . 2.
p . 92. Ag . S p . A lg . V. 1. p . 468. S y s t . A lg . p . 174. S p r e n g . S p . P I . v . 4. p . 365.
Ectosperma cæspitosa, V a u c h . C o n f . p . 28. t . 2 . f . 4.
Conferva amphibia, D illw . B r i t . C o n f . t . 41.
H a b . On the margin of rivulets, the wood-work of mill-dams, and
banks exposed to the constant trickling of water. Annual. At all
seasons, but producing fructification in the spring. Very common.
Fronds densely interwoven into a widely spreading and thick spongy
mass, the extremities of the branches often causing the surface to resemble
the pile of coarse velvet. The branches appear to be irregularly
dichotomous ; it is impossible to ascertain the length of the filaments,
they ai-e so densely matted together; and their lower extremity
loses its colour, and dies, while the upper part is in a state of progressive
vegetation. Vesicles spherical, dark green, sessile, situated
in opposite pairs just beneath the apex of the branches. Substance
of the filaments tender and membranaceous. Colour a rich dark green,
changing to a dirty white in decay.
One of the most common species of the genus, inhabiting places
where there is a constant supply of trickling moisture, especially
upon a muddy or clayey surface. The masses which it forms often
become pendant by their own weight, holding water like a sponge, and
presenting the most beautiful green surface. Immediately beneath the
surface, however, the filaments become pale and at last colourless.
When growing by the side of a rivulet, the frond occasionally loses its
closely matted character, and is carried out for several inches. Dr
8. V a u c h e r ia r a c e m o s a .
Fronds capillaiy forming dense entangled floating masses, vesicles in
pedunculate racemose clusters.
Vaucheria racemosa, D e C a n d . L y n g b . H y d r o p h . D a n . p . 82. t . 23. A g . S p . A lg . v . 1.
p . 469. S y s t . A lg . p . 175. G r e v . F l . E d in . p . 306. S p r e n g . S p . P I . v . 4 . p . 365.
Ectosperma racemosa, V a u c h . C o n f . t . 3. f . 8.
H a b . In ponds and ditches. Annual. Summer. In the neighbourhood
of Edinburgh.
Fronds very slender, several inches in length, floating in large entangled
masses, flexuose, subdichotomously branched. Vesicles ovate,
dark green, five in number or more, sessile or subsessile in a clustered
manner upon a common peduncle or receptacle, given off at a right
angle from the branches. Substance membranaceous. Colour a bright
green.
This species is easily distinguished by the fructification. In mode
of growth it most resembles V. geminata.
Ge n u s LIV. BOTRVDIUM, Wallr. Tab. XIX.
Ge n . Ch a r . P lan t a spherical vesicular receptacle, filled
with a watery fluid, dehiscent a t the apex, terminating
below in a radicating tuft of fibres.
Obs. Very little is known of the real nature of this plant. It associates
so incongruously with the Vaucherioe, that no botanist, consult-
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