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F amily I. ULVAOE^.
Thallus membranaceous, or foliaceous, rarely crustaceous,
formed of one stratum of cells, eitber expanded, or tubulose, or
vesiculose.
Propagation by zoogonidia, arising from a repeated division
of tbe cytioplasm. Zoogonidia oblong, furnished at one extremity
with two or four cilia.
Sub-Family 1 . P ea s io l ea i.
Thallus expanded and foliaceous, rarely crustaceous.
Genus 54. F R A S IO LA . Ag. (1821.)
Thallus membranaceous foliaceous, ascending or erect, more
or less críspate, composed of angular cells, distributed in plane
areas ; base sometimes loosely fibrillose.
Vegetation by division of the cells in two directions.
F z a s io la c r is p a . Kutz. Tab. Phyc. V. t. 40, /. 6.
Tufts more or less dense, often long and widely expanded,
dark green, soft and elastic. Thallus plicate crisped, of variable
form and size, often búllate ; cells arranged in distinct areolas,
or confluent, quadrate, or oblong-quadrangular, now and then
twice as long as the diameter ; angles more or less obtusely
rounded.
S iz e . Cells -OOS-'OOO mm. diam., or -OOfl-'OlS mm. x
•003-‘005 mm.
Jessen Mon. Pras. 1 .1, f. 10-16. Eabh. Alg. Eur. iii, 308.
Lagerstedt, Pras. p. 19.
Ulva crispa, Hass. Alg. t. 78, f. 12. Eng. Flora v., p. 312.
Fng. Bot. ed. i, 2754; ed. ii, 2406. Lightf. FI. Scot. 972.
Harv. Man. 171. Grev. FI. Edin. 299. Hook FI. Scot. ii., 91.
Mack. FI. Hib. 243. Hull Br, FI. 309. Abbot. FI. Bedf. 273.
Johnst. FI. Berw. ii., 250. Jenner. Tunb. Wells 190.
Ulva lactuca y, Huds. FI. Ang. p. 567. Dillen. Muse. t. 9,
f. 6.U
lva terrestris, Gray. Arr. i., 344.
Tremella crispa, With. Arr. iv., 81.
On damp ground, rooks, &c.
Hassall unites this species and the next together in one, but his
example hag not been followed by his successors.
Common on moist shady ground, especially near houses and walls,
sometimes on old thatched roofs. Fronds very much crowded, forming
a dense stratum, rather lying on the soil or medium than attached to i t ;
deep green, rounded, thin, tender, but not gelatinous, variously curled
and folded. Quaternate granules beautifully arranged in sqnares, contained
in larger ones, and separated by parallel pellucid lines, the whole
compared by Agardh to the walks and parterres of a garden. Annual.
Found throughout the winter and early spring.—Eng. Bot. p . I l l-
Plate L. Jig. 1. Plants slightly magnified. Fig. 2, portion of a frond
X 400.
F z a s io la fu z fu z a c e a . .. Cenni, p. 36.
Forming a furfuraoeous stratum, more or less expanded, dark
green. Thallus about a line long and broad, dilated from the
short stem-like base into a fan-like lam ina; margin slightly
undulate and repand, often emarginate at the apex or lobed.
Cells angular, arranged in regular quadrate, or almost quadrate
areolas.
S iz e . Cells -014--016 x -004--006 mm.
Jessen, Mon. Pras. t. 2, f. 1-10. Kabh. Alg. Eur. m., 309.
Lagerstedt Pras. p. 82.
Ulva furfuracea, Grev. So. Crypt. FI. t. 265. Eng. FI. v., p.
812. Harv. Man. 171. Eng. Bot. ed. ii,, p. 112. Grev. Alg.
B ritt. 176, t. 18. Mack. FI. Hib. 244.
On damp walls and rocks.
“ Fronds closely tufted, forming a vivid green stratum, a yard or more
in extent, two or three lines in length, erect, obovate, truncated, and
usually eroded at the top, tapering at the base into a longish claw;
margin inflected , substance firm, and void of lubricity. Cells in tonrs.
I t does not adhere to paper.”—Cai'm.
Plate L. fig. 5. Fronds slightly magnified. Fig. 6, yonng frond X 400.
Fig. 7, lower portion of mature frond X 400.
F z a s io la s t ip i t a t a . Suhr. in Jessen Mon. t. 2, f. 11-16.
Stratum caispitose, expanded, dark green. Thallus of
variable form and size, commonly one to two lines, rarely four
lines long ; dilated upwards from a stem-like base (lanceolate,
obovate, oboordate, reniform, ilabelliform, &c.), often truncate
at the apex ; margin slightly repand ; cells ^ in the stem-like
base in series, in the upper p a rt disposed in small regular
areolas.
S iz e . Cells -005-'007 mm.
Jessen, Prasiola p. 16, t. 2. Eabh. Alg. Eur. iii., 309.
Lagerstedt. Pras. p. 86, fig. 4.
On rocks by the sea, &c.
Jessen, in his monograph of this genus, gives figures of the fronds of
some Irish specimens of the above species, which he had seen and
examined. It is, on the faith of this, included here, although it appears
to be the most marine of any of the four,
Plate L. figs. 8.9. Fronds of P. stipitata magnified 4 diam. Fig. 10,
young frond X 400. Fig. 11, part of mature frond X 400. All after
Jessen.
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