Ulva compressa L.

1920]
Setchell-Gardncr: Chlorophyceae
251
4. Enteromorpha compressa (L.) Grev.
Plato 14, figs. 7, 8; plate 16, fig. 3
Frond tubular, more or less compressed, sometimes constricted,
varying much in dimensions; branches usually simple, cylindrical or
expanding above, in either case narrowed at the base, similar in appear-
ance to the main axis; cells in no definite order; membrane rather thin.
Growing in the middle and lower littoral belts. From Alaska
(Bering Sea) to Mexico (Magdalena Bay).
Greville, Alg. Brit., 1830, p. 180, pi. 18; Collins, Green Alg. N. A.,
1909, p. 201, Mar. Alg. Vancouver Is., 1913, p. 101 ; Setchell and
Gardner, Alg. N. \V. Anier., 1903, p. 213. Enteromorpha prolifera
Setchell and Gardner, Alg. N.W. Araer., 1903, p. 221 (as to no. 5087
only)- Enteromorpha fascia l'ostels and Ruprecht, lllust. Alg., 1840,
p. 21 ; Setchell and Gardner, Alg. N.W. Amer., 1903, p. 211 ; Collins,
Green Alg. N. A., 1909, p. 204. Viva compressa Linnaeus, FI. Suec.,
Ed. II, 1755, p. 433.
We have followed the opinion of J. G. Agardh (1883, p. 137) a.s
to the nature and limits of Enteromorpha compressa. The habit of
typical plants is well illustrated in our figures (plate 14, figs. 7, 8, and
plate 16, fig. 3). The branches may arise from the very base or at differ-
ent heights along the axis. They are uniformly constricted at the base
and usually expanded to a rounded tip. The broader portions of the
frond are almost always flattened and the layers may be very imper-
fectly separated. Sections of such imperfectly tubular fronds often
bear a striking resemblance to those of Tllva Lima, especially when
separation is present only on the margins as may happen in spots.
The differences between Enteromorpha compressa and E. minima
have already been noticed under the latter species. The resemblance
to narrow forms of Viva JAnza is sometimes puzzling, especially in
unbranched specimens (var. sub simplex J. Ag.) or in specimens only
slightly branched.
We refer under Enteromorpha compressa the E. fascia of Postels
and Ruprccht (1840, p. 21) since the habit (plate 16, fig. 3) is the
same and the size and shape of the cells, both in surface view and in
cross section, are identical. The cell contents, however, in the type
specimens of E. fascia are disorganized in such a way as to seem
almost as if there were groups of small cells within the larger ones.
The color of the type specimens is also somewhat brownish. We
ascribe this as well as the peculiar appearance of the cell contents to
.a ; hc.il
Enteromorpha compressa (L.) Grev.
Fig. 3. A habit sketch of a frond. X 1.
252
University of California Publications in Botany [Vol. 8
some abnormal state or unusual treatment of the specimens. The type
specimens of E. fascia, as they wrere found in the Imperial Academy
of St. Petersburg in 1903, were labelled as having been collected by
the Luetke Expedition in Kamtschatka.
Of specimens distributed from our coast we find in our copy of
the American Algae that Tilden’s no. 265, under the name of E. com-
pressa var. complanata is E. crinita, and no. 264, under the name of
E. compressa var. subsimplex is E. piumosa.
Most of the specimens available to us for examination are close to
the typical form of E. compressa but certain plants collected by one
of us (Gardner) at Coos Bay, Oregon, seem referable rather to vai-.
stil)simplex J. Ag. (1883, p. 137).
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lìnteromorpha compressa (L.) Grev.
Fig. 7. A vertical section througli thè froml. X 250.
Fig. 8. A surface view. X 2.10.
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