Glossary - Freshwater Algae: Identification, Enumeration and Use as Bioindicators - page 255

epivalve + epicingulum derived from the mother cell.
The larger of the two halves of the diatom cell wall,
into which the hyptheca fits.

Glaucous Greyish-green or green with a white
overcast

Glycogen A starch-like storage product found in
blue-green algae

Epivalve Flat surface (face) of the epitheca - cir-
cular in centric diatoms, elongate in pinnate diatoms

Gonidia Spore-like thick-walled reproductive cells
in blue-green algae

Exospore A spore produced by budding from
another cell in blue-green algae

Gullet A canal or groove at the anterior end that
opens at its base to a chamber. Found in some flagel-
lates

Eyespot A complex of granules, usually red or
brownish in colour, sensitive to light and found in
some motile species

Haptonema A flagellum-like organelle linked to
the basal bodies of flagella found in the Haptophyta.

False branching Branching formed by a different
filament growing sideways and not by a single cell
giving rise to two or more cells that develop into new
branches (see Fig. 4.21)

Heterocyst An enlarged cell present in some blue-
green algae with thickened walls and often with a
highly refractive appearance making it distinct from
other cells. Associated with nitrogen fixation

Fibula In diatoms a bridge of silica between parts
of the valve either side of the raphe

Heteropolar The two ends (poles) of a diatom cell
are differently shaped

Filament A series of cells forming one or more
rows in a linear arrangement (cells stacked end to
end)

Heterovalvar Each valve of a diatom is a different
shape

Flask-like Wide at the base and abruptly narrowing
to a neck

H-pieces Sections of a cell wall in a filamentous
species where the wall is composed of two overlap-
ping halves that appear shaped like an H. When the
cells of the filament separate (or break) they do so
at the centre rather than at the cross walls between
two cells. The H-pieces are often more obvious at a
filament end

Frustule The cell wall in diatoms which is made of
silica and is composed of two halves (valves) linked
together by a number of bands called collectively the
girdle

Fusiform An elongate shape widest at the centre
and tapering at each end (spindle or cigar-shaped)

Hormogonium (pleural hormogonia) a short part
of a filament in blue-green algae that can be released
and form a new filament thus serving as a reproduc-
tive and dispersal mechanism

Gas vacuole A protein covered gas-filled organelle
found in cyanophyta

Genuflexed Crookedinthemiddle,bentatanangle
similar to a person bowing at the knee

Hyaline Transparent and colourless

Hypocingulum Cingulum within the epitheca

Gibbous Swollen to form a small locally occurring
bump usually at the centre

Hypocone The lower part or posterior portion of a
dinoflagelate cell

Girdle The zone of silica bands linking the two
halves of a diatom frustule

Hypotheca The smaller of the two halves of the
diatom cell wall, fits into the epitheca

Girdle view Side view of a diatom frustule, show-
ing the girdle or area where the two halves of a diatom
cell join (as opposed to the valve view when the girdle
generally cannot be seen)

Hypovalve Flatsurface(face)ofthehypotheca,cir-
cular in centric diatoms , elongate in pennate diatoms

Imbricate Overlapping