Environmental Engineering Reference
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100 μm
100 μm
100 μm
Figure 4.81
Micrasterias.
The two semicells of this
desmid are demarcated by a deep median groove
(arrow).
Figure 4.80
Closterium
. Top: Crescent-shaped
species (
C. moniliferum
) with two chloroplasts con-
taining pyrenoids (arrows). Bottom pair: Very narrow
(
500 μm long) celled species (
C. aciculare
) common
in phytoplankton, showing a pair of cells (lower figure)
and chloroplast detail with pyrenoids (arrows - upper
figure).
>
is present with or without a pyrenoid.
Very common in eutrophic lakes and
slow flowing rivers. Some species also
occur in more acid waters. Chlorophyta.
Plate XXX.
almost filling the cell. A pyrenoid may
be present. Abundant in the plankton of
eutrophic lakes. Chlorophyta. Plate XXX.
Fig. 4.79.
223
(219) (a) Cells straight with rounded or trun-
cated ends. ....................
Penium
Cells of
Penium
can be up to 10 times
long as wide. They are cylindrical in
shape, arranged in two halves each of
which has a chloroplast with one to sev-
eral pyrenoids. A small median constric-
tionmaybepresentinthetruncatedapices.
Cell wall smooth or sometimes punctate.
Cells 7-26 μm wide, 10-274 μm long.
Common, often in acidic waters. Chloro-
phyta. Plate XXX.
(b) Cells needle-shaped and occurring in
loose, irregular bundles or tangled groups
......................
Ankistrodesmus
The cells of this alga are very simi-
lar to
Monoraphidium
(which used to
be included in this genus)
but occur
in groups or bundles. A mucilage enve-
lope may be present. Cells (1-5 μm
wide, 20-165 μm long) have a nar-
row spindle shape and may be curved
or twisted. A single parietal chloroplast
(b) Cells slightly or strongly curved with
tapering ends ..............
Closterium
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