Glossary of Terms for Freshwater Algae   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
aerial	Growing in a habitat above the ground or water
akinete	A thick-walled spore that can survive harsh conditions and functions as an asexual resting stage
algaenans	Hydrocarbon polymers that help some algal cells resist decay
anisogamy	Sexual reproduction involving two types of gametes of different sizes or shapes
antheridium	A cell that produces male gametes
apical cell	Cell located at the end of a filament or thallus
aplanospore	A nonflagellate spore that may be genetically capable of producing flagellated cells under the right conditions; produced by divisions of the parent cell
araphid diatom	Diatom lacking a raphe structure on either valve
areolae	Pores or perforations in the siliceous valves of diatoms
asexual reproduction	Reproduction involving the cells of a single parent
autocolony	A miniature version of the parent colony produced asexually by one of its cells; a coenobium
autospore	A nonflagellate spore
axial	A chloroplast located in the center of a cell along its longitudinal axis
basal	Concerning the base of a thallus or filament
benthic	Inhabiting the bottom of an aquatic environment
biflagellate	Cells with two flagella
bloom	Visible or nuisance algal growth often associated with nutrient-rich conditions
blue-green algae	See cyanobacteria
brackish	Slightly salty waterbodies
calyptra	Thickened or enlarged tip of a cyanobacterial filament
charophyceans or charophyte green algae	The group of green algae most closely related to the land plants, includes the zygnematalean algae (Spirogyra and the desmids) as well as several other genera and the stoneworts
chlorophyll-a	Primary photosynthetic pigment in algae and higher plants
chlorophyll-b	Photosynthetic pigment found in higher plants, green algae, and some euglenoids
chlorophyll-c	Photosynthetic pigment found in chrysophytes, synurophytes, diatoms, tribophytes, dinoflagellates, cryptophytes, and brown algae; includes c1 and c2 components
chlorophyceans	Green algae
chloroplast (plastid)	Membrane-bound organelle involved in photosynthesis
chrysophytes	Mixotrophic algae with golden-brown pigmentation
chytrids	Group of small, colorless fungi that may parasitize algal cells
chromatophore	An organelle that contains pigments; i.e. a plastid
cingulum (pl. cingula)	In the dinoflagellates, a transverse groove that usually holds the transverse flagellum; another term for girdle band
coenobium (pl. coenobia)	A type of colony with a genetically-predetermined morphology and number of cells; each cell of the parent colony can produce an autocolony that is an exact replica of the parent colony
coenocytic	Multinucleate and lacking tranverse cell walls; siphonous
conjugation	In the zygnematalean algae, sexual reproduction involving nonflagellate gametes that combine in a special tube or structure; see also lateral and scalariform conjugation
contractile vacuole	A membrane-bound vesicle that expands and contracts to expel excess water
cross walls	Transverse cell walls
cyanelles	The blue-green plastids of the glaucophytes that originally resulted from an endosymbiotic event
cyanobacteria	Photosynthetic bacteria with a characteristic blue-green color, commonly known as the blue-green algae
cytokinesis	Division of the cytoplasm during cell division
desmid	A group of unicellular or filamentous green algae; see also placoderm desmids and saccoderm desmids
detritus	Dead or decaying organic matter
diatoms	Photosynthetic microalgae with siliceous cell walls
dioceious	Organisms in which male and female (or + and -) gametes are produced on different individuals
dinoflagellates	Unicellular algae that are often covered in thick, armoured plates
double false branching	Growth pattern that occurs when a filament breaks apart (often at a dead cell or heterocyst) and both pieces emerge through the mucilage sheath and continue to grow
embryophytes	The group consisting of bryophytes and vascular plants
endosymbiont	An organism that lives inside another, benefitting both individuals
epilithic	Growing on the surface of rock or stone
epiphytic	Growing on the surface of plants or other algae
eutrophic	Waters rich in dissolved nutrients (especially nitrogen and phosphorus); leads to accelerated growth of algae and plants that depletes oxygen levels and reduces biodiversity
euglenoids	Organisms that are unicellular or colonial, colorless or pigmented, and may move with an undulating, shape-changing motion (see metaboly)
eyespot	A light-sensitive, red-pigmented spot usually found in the cell anterior of some flagellated algal cells or reproductive cells; sometimes called a stigma
false branching	Single false branching occurs when a filament breaks apart (often at a dead cell or heterocyst) and one piece emerges through the mucilage sheath and continues to grow; see also double false branching
flagellum (pl. flagella)	A long, whiplike organelle that usually protrudes from a cell and is used for motility
fragmentation	Type of asexual reproduction where the parent thallus breaks into pieces to form new individuals; may be accidental or genetically programmed
frustule	The siliceous components of a diatom cell; i.e. the valves and girdle bands
fucoxanthin	A brown carotenoid pigment used in photosynthetis, found in the golden-brown and brown algae
gametes	Reproductive cells
gas vesicles	In cyanobacteria, cylindrical structures used to increase cell bouyancy
gas vacuoles	Sometimes synonymous with gas vesicles, also refers to a group of gas vesicles
girdle band or cingulum (pl. cingula)	In diatoms, the rings or bands of silica encircling the valves where they overlap. In desmids, the short wall segments oriented transversely at the central portion of the cell
glaucophytes	A group of algae that contain blue-green plastids called cyanelles, sometimes called Glaucocystophytes
golden-brown algae	Algal groups with golden pigmentation; i.e. the chrysophytes, synurophytes, haptophytes, and diatoms
gone	In the desmids, a cell derived from zygote germination that may not have the typical morphology of that species
grana (pl.)	Stacks of thylakoids found in the discoid chloroplasts of land plants and some green algae
green algae	Morphologically diverse group of algae with green-pigmented chloroplasts
hair cells	Elongate, usually colorless cells or extensions of cells found at branch apices, increases surface area for nutrient and gas exchange and may protect the cells from herbivory
halophilic	Inhabiting a salty environment
haploid	Having a single set of chromosomes
heterocyst	In some cyanobacteria, a large, thick-walled cell involved in nitrogen fixation
heteropolar	Filaments with distinct basal and apical components or cells that are assymetrical along the transverse axis
heterotrophic	Organisms that feed on organic matter from external sources, and are osmotrophic or phagotrophic
holdfast cells	Structure that attaches a thallus or filament to the substrate
hormogonium (pl. hormogonia)	In filamentous cyanobacteria, short, usually motile segments that break off from the main filament and are used for asexual reproduction and dispersal
hypnospore	A thick-walled resting cyst
hypnozygote	A thick-walled, nonmotile resting zygote that remains dormant for a period of time until germinating when conditions improve; found in green algae, dinoflagellates, and some other flagellated organisms
intercalary	Located in the middle of a thallus, not on the end
isogamy	Sexual reproduction involving two types of gametes that function differently but are morphologically identical
isopolar	Symmetrical along the tranverse axis, having the same morphology at both ends
isthmus	In desmids, the constricted region between the two semicells that usually contains the nucleus
lateral conjugation	Conjugation where two cells on the same filament reproduce within a conjugation tube
littoral zone	Region near the shore of lakes, ponds, or large rivers
lorica	A protective covering surrounding flagellated cells of some algal groups
meristem	Portion of a thallus where the cells are able to divide and produce new growth
metaboly	Shape-changing motion of the euglenoid genera that does not involve flagellar movements
metaphytic	Growing among the floating microscopic community in the littoral zone that is often associated with aquatic plants
mixotrophic	Cells with both photosynthetic and heterotrophic or phagotrophic nutrition
monoecious	Organisms in which male and female (or + and -) gametes are produced on the same individual
monophyletic	A group of organisms that share a single common ancestor
multicellular	Composed of more than one cell
multinucleate	Having many nuclei
necridic cells (necridia)	Dead cells in cyanobacteria that disrupt the main filament to produce false branching or hormogonia
oligotrophic	Waters low in nutrients and organic production, typically rich in biodiversity
oogamy	Sexual reproduction involving the fusion of a small, flagellated male gamete with a larger, nonflagellated female gamete
oogonium (pl. oogonia)	A female reproductive structure capable of producing one or more eggs
osmotrophic	Organisms that feed on dissolved organic molecules absorbed from the outside environment
parietal	Near the outer or peripheral surface of a cell or thallus; commonly used to describe chloroplasts situated along the cell wall
pellicle	The surface covering of euglenoid cells composed of proteinaceous strips in a helical pattern
periphytic	Growing attached on the surfaces of plants, other algae, or other substrates
phagotrophic	Organisms that feed by ingesting particulate organic carbon or intact cells
phototaxis	Movement in response to light
photosynthetic	Organisms that use sunlight as an energy source to synthesize carbohydrates from carbon dioxide and water
phylogenetic	Concerning the relationships of evolutionary development
phytoplankton	Floating or swimming microscopic algae and cyanobacteria
placoderm desmids	Unicellular or pseudofilamentous desmids with cell walls made up of two parts of different ages separated by a central isthmus that are covered in pores
plastid	See chloroplast
polar nodule	In cyanobacteria, thickened regions where the heterocyst cell wall attaches to a vegetative cell
polyeders	In Hydrodictyon and Pediastrum, polygonal cells produced from zygote germination that give rise to new coenobia
polyphyletic	A group of organisms descended from more than one ancestor, may be more closely related to other organisms outside of the taxonomic group
protoplasm, protoplast	The living substance of a cell
pseudofilament	Loose chain of individual cells held together by mucilage or attached at the end walls, rather than sharing a common cell wall as in a true filament
pyrenoid	A proteinaceous structure associated with algal chloroplasts that often forms storage compounds
quadriflagellate	Cells with four flagella
raphe	In diatoms, a slit in the valve face that allows the cell to move along a substrate
rhizoid	Rootlike extensions usually used to attach a thallus to the substrate
saccoderm desmids	Desmids with a homogeneous cell wall that lacks pores; are not differentiated into two semi-cells
scalariform conjugation	Conjugation involving two filaments that allign laterally and form conjugation tubes between adjacent cells in a ladder-like arrangement
semicell	In placoderm desmids, one-half of a cell
sexual reproduction	Reproduction involving the cells of a single parent
silica deposition vesicle	Involved in the formation of the siliceous valves of diatoms and siliceous scales of chrysophytes and synurophytes
siphonous	See coenocytic
striae	Term used to described elongated markings on the cell walls of desmids and diatoms
subaerial	Growing on or near the earth's surface
sulcus	In dinoflagellates, a longitudinal groove in the ventral side of the cell that holds the longitudinal flagellum
suture	In dinoflagellates, the regions between thecal plates
syngamy	The fusion of two gametes during fertilization
synurophytes	Motile flagellates covered by siliceous scales; the scaled chrysophytes
terminal	Located at the end of a thallus
thallus	General form of an alga that, unlike a plant, is not differentiated into stems, roots, or leaves
thylakoid	Flattened membranous sacs that form the chloroplast membranes
tribophyte algae	See yellow-green algae
trichome	A filament of a blue-green alga or cyanobacterium
trichogyne	In some charophycean green algae and in the red algae, the elongated portion of the female reproductive structure that recieves the male gametes
turbidity	Measure of the cloudiness of a waterbody due to suspended particles
unicellular	Composed of a single cell
uniseriate	Composed of a single row of cells.
valve	In the diatoms, the two siliceous halves of the cell wall
vegetative cells	Cells involved in growth, nutrition, or asexual reproduction, but not sexual reproduction
vesicles	SDV, gas
yellow-green algae	Rare algae with yellow-green pigmentation; the tribophyte algae
zoospore	A flagellated spore
zygospore	A thick-walled resting spore formed from the fusion of gametes or a fertilized oogonium
zygote	The cell resulting from the fusion of two gametes