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Ser. C hlokospermeæ. Fam. JJlmceæ.
P l a t e CLXXI.
ULVA LATISSIMA, L im .
Gen. C h a r. Frond membranaceous, green, expanded, plane, (in some
cases saccate when young,) composed of irregular cells. Fructification
; granules, often arranged in fours, scattered over the whole frond.
U lva,—supposed to be from Til, water, in Celtic.
U lva latissima-, fro n d broadly-ovate or oblong, flat, o f a fu ll green colour.
U lva latissima, TÂwn. FI. Suec. p. 433. Ag. Sp. Alg. vol. i. p. 407. Ag.
Syst. p'. 188. Ch-eo. Alg. Brit. p. 171. Hook. Br. Î Ï . vol. ii. p. 811.
Wyatt, Alg. Banm. no. 33. Harv. in Mack. FI. Hib. p a rt 3. p. 342.
Harv. Man. p. 170. J. Ag. Alg. Medit. p. 17. Kiitz. Fhyc. Gen. p. 396.
Mont. FI. Alg. p. 149. Endl. 3rd Suppl. p. 19.
U lva lactuca, Sm. F. Bot. 1 .1551. {not of Linn)
Ulva lactuca, var. latissima, lightf. FI. Scot. p. 971.
H a b . On rocks and stones in the sea between tide marks ; and extending
to ten fathoms water, or perhaps a greater depth. Annual. Summer
and autumn. Very common on the British shores.
Geogr. D is t e . Throughout the ocean, nearly to the limits of vegetation iu both
hemispheres.
D esck. Root, a small disc. Fronds from six to twenty inches in length or more,
and fi'om three to twelve in breadth, growing in tufts ; very variable in
shape, oblong, or ovate, with the margin more or less sinuated and wavy,
variously plaited, glossy, translucent, of a very soft, but rather firmly
membranous, though exceedingly thin, substance, and vivid green colour.
In old age the fronds are frequently found pierced by holes, and infested
with Myrionemata, and are then usuafly of a pale green colom. Sometimes,
especially in specimens dredged from deep water, the colour is of a very
dark, and even bluish green, reflecting glaucous tints when under water.
In drying, this plant loses much of its brilliancy, and scarcely adheres to
paper. Structure composed of two strata of exceedingly small, fully
coloured ceUs of irregular shape, separated by an imperfectly coloured,
thin, cellular layer.
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An exceedingly common species, found on all shores, and
nearly in all latitudes. Except on the extreme antarctic coasts,
where all vegetation, save the Liatomaccce, is at an end. Viva
latissima may be said to inhabit every shore. It is as abundant
in the tropics as in the temperate zone. Nor do specimens from
different countries exhibit many minor points of difference. Some
are of more rigid texture than others, but there is little else peculiar
about them. The form is too variable among specimens
VOL. II. N
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