Accessory pigment – any photosynthetic pigment that absorbs light and transfers the energy to a reaction center of chlorophyll “a”

Acellular – not made up of cells or lacking segregative material within a bounding layer

Acellular siphon – a tube or large, multinucleate cell that lacks segretative material within a bounding layer

-aceae – a suffix added to stem of name or a synonym of a type genus to form a family name (e.g. the brown algae Laminaria and family Laminariaceae)

Acrochaetioid – a thallus resembling the red algae genus Acrochaetium (Nemaliales) in being microscopic, filamentous, branched or unbranched

Acute – sharp-pointed, tapering sharply to a point or with a narrow axis

Adeloparasite – referring to a parasite that is closely related phylogenetically  to its host

Adherent – the union of separate parts; tending to adhere to or be connected by contact

Adjacent - situated near

Agar – a phycocolloid characteristic of the Rhodophyta; a sulfated polysaccharide occurring in the cell walls and intercellular spaces of certain rhodophytes; it is extracted primarily from Gelidium and Gracilaria and used commercially for its gelling properties

Agarophyte – an algae from which agar can be obtained

Aggregated – crowded together but not grown together

Air bladder – a small bladder containing a variety of gases and aiding in the buoyancy of certain algae (e.g. fucoid brown algae)

Alga – a Latin word for seaweed; also used to describe one of a heterogeneous collection of algae characterized by being autotrophic, by reproduction through partly or entirely unprotected reproductive walls; zygotes that are not enclosed within a nourishing female gametophyte tissue; and by having a broad range of structures from unicells to mulitcellular thalli having the potential of becoming complex in structure but lacking true roots, stems and leaves typical of embryo forming plants

Algin – the soluble sodium salt of alginic acid, being a complex organic phycocolloid obtained from the cell walls of large brown algae, especially kelps composed of d-mannuronic and L-guluronic acids

Alginate – a general term for salts of alginic acid, especially sodium but also calcium or barium ions

Alginic acid – a linear polysaccharide occurring in the walls of many brown algae and consisting of beta-1, 4-linked d-mannuronic acid units; a phycocolloid from brown algae widely used in industry as suspending agents, thickeners and emulsifiers

Algology – an older name for the study of algae now usually replaced by the term phycology

Alien – an introduced organism that has become naturalized

Aligned – rows of adjacent cells with end walls at the same level, as in polysiphonous construction

Alloparasite – referring to a parasite that has no particular relationship to its host i.e.  placed in a remote taxa, different orders, etc.

Alternate – arranged in two rows but not opposite nor secund on the axis

Alternation of generations – a sequence in a life cycle in which a haploid, gamete-producing phase is followed by a diploid, sporeproducing phrase; the spores of the latter reinitiate the haploid phase; also the reproduction by organisms that do not necessarily or precisely resemble the parent, but the grandparent

Amphi – a Greek word for around, double, on both sides, or of two kinds

Analogous – resembling but not being homologous

Annual – living for less than one year, during which time the life history is completed; of one year’s growth

Antheridium – the male reproductive organ (gametangium) that produces sperm in oogamous sexual reproduction; the mother cell of antherizoids

Anticlinal – perpendicular to the surface of a structure

Apex – pertaining to the apex (tip), distal end, top, or terminal end

Aphotic – lacking light

Apical cell – a prominent meristematic cell at the apex or tip of an algae

Apical growth – growth at the tip of an alga or its branches; normally refers to cell multiplication as well as cell elongation

Apical meristem – a single actively dividing cell or cells located at the apex

Appressed – lying closely to the substratum for the whole of its length or surface; pressed close without being united; in close physical contact

Arborescent – bushy, tree-like or growing in the form of a tree

Arcuate – curved, as a bow, bent

Articulate – segmented, jointed or jointed in appearance; having a series of calcified segments seperated seperated by flexible uncalcified joints

Articulated coralline – a calcareous alga of the family Corallinaceae (Rhodophyta) in which the stony segments are seperated by minute uncalcified, flexible joints

Ascending – directed upwards

Aseasonal annual – an annual or short lived alga found throughout the year but as multiple, overlapping generations

Asexual reproduction – reproduction that does not involve a union of gametes; reproduction by a vegetative structure

Assimilatory branchlets/filaments/hairs/shoots – photosynthetic structures with chloroplasts; often thin and short lived when compared with small branches

Asurgent – curving obliquely upwards from its origin, ascending; said of essentially horizontal filaments that turn upwards

Asymmetric – a branching pattern or shape that lacks a line of symmetry on either side of a median plane

Attachment-disc – the holdfast or basal hapteron of an alga

Attenuate – narrowly and gradually tapering to a long slender point; also slender and thin

Authority – person who named a given species and whose name appears after the Latin generic and specific epithets of an alga; the last part of the complete scientific citation of an organism

Autotrophic – synthesizing food from carbon dioxide and water as in photosynthesis, photosynthetic

Axial cell -  a cell within or a part of the plant axis and surrounded by pericentral cells; the central cell of an axis, sometimes distinguishable among medullary cells in transverse section of the axis

Axis – a line or longitudinal center of an object bearing laterals; the stem-like stalk

Band-shaped chloroplast – an elongated chloroplast with parallel or roughly parallel sides

Basal – towards the base or point of attachment (apical)

Basal filament – unistratose, basal layer of thallus filaments

Biradiate – consisting of two major radiuses

Biseriate filament – filament consisting of two rows or columns

Bladder – a vesicle containing a variety of gases and aiding in the buoyancy of certain algae, such as the fucoid brown algae

Blade – a flat, leafy portion of an algae; part of a thallus that is erect and more or less flattened

Calcareous – impregnated or containing large amounts of lime; chalk-like, limy or stony

Calcified – involving deposition of calcium carbonate in or on cell walls or the thallus; encrusted or impregnated with calcium carbonate

Carposporangium – a sporangium in the red algae that is formed by the carposporophyte and that contains carpospores

Carposporophyte – a minute plantlet or life history stage formed on the female gametophyte after fertilization, consisting of diploid gonimoblast filaments, the carpogonium and its accessory cells, the bearing carposporangia

Carrageenan – a phycocolloid characteristic of some Rhodophyceae; a sulfated galatan located extracellularly; various fractions are recognized based upon solubility differences; a mucopolysaccaride in the wall or some red algae, being a polymer of galactose

Cartilaginous – firm and tough but somewhat flexible; with a tough texture rather like cartilage

Chlorophyll -  a group of fat-soluble, photosynthetic green pigments found in algae and plants

Chlorophyta – a division of photosynthetic organisms whose members contain chlorophylls a and b, stire excess food as starch and which reproduce through exposed spores or gametes are not enveloped by vegetative tissue; the evolutionary line from which embryo-producing plants arose

Chloroplast – a double membrane-bound semiantonomous organelle in the cytoplast of eukaryotes and containing elaborated membranous sacs embedded in a protein-rich stroma and containing a variety of photosynthetic pigments

Clavate – wedge or club-shaped, broader towards the apex

Coenocyte – an organism or segment of an organism containing many nuclei in a common cytoplasm; multinucleate and without transverse walls

Coenocytic – an adjective for a coenocyte

Colony – a group of cells resulting from cell division

Columnar – cyclindrical and much taller than broad

Compensation depth – depth of water where there is sufficient light so that photosynthesis equals respiration over a 24-hour period

Conceptacle – an investigation or cavity (either sunken or with in a raised dome) with one or more openings to the thallus surface and bearing reproductive organs

Conchocelis stage – diploid, filamentous, sporophyte phase; a microscopic, filamentous phase in the life histories of some bangialean red algae

Congener – member of the same genus; another organism of the same genus

Conspecific – belonging to the same species

Constricted – drawn together or contracted; narrow regions lying between swollen or larger adjacent regions

Contiguous – adjacent

Coralline – calcified alga belonging to the family Corallinaceae; articulated or jointed calcareous red alga

Coralline alga – the calcified encrusting and articulated red algae

Cortex – the outer tissue regions of a thallus, containing photosynthetic pigments and usually characterized by dense compacting or loose arrangement of its component branchlets, filaments or cells

Cortical – pertaining to the cortex

Cortical band – ring of periaxial cells, with varying amounts of cortical tissue, formed around nodes; a nodal band in which uncorticated internodes alternate with corticated nodes

Corticating filament – a filament forming a superficial investiment

Cortication – a secondarily formed outer cellular covering over part or all of an algal thallus

Cruciate – cross-shaped

Cruciate tetrasporangium – tetrasporangia, with the divisions at right angles to each other

Crustose – crust-like, in a layer or layers flattened against the substratum; forming a firm to hard thallus on a substratum, often referred to fleshy or calcified crusts

Cryptostomata – pits or flask-shaped structures in blades and opening to the outside, containing hairs, as in fucoids

Cuspicate – with a sharply pointed tip

Cylindric – elongated with a circular outline in transverse section

Cytoplasm – that part of the protoplasm that excludes the nucleus

Deciduous – falling off naturally after a time, not persistent nor permanent

Decussate – arranged in opposite pairs that are 180 degrees from each other

Descending – tending gradually downwards

Determinate branch – a lateral branch having limited growth potential

Dichotomous – bearing two equal branches at each branch point; having division always in pairs; evenly forked like the arms of the letter “Y”

Dichotomous branching – forking into equal or unequal branches

Diffuse growth/branching – generalized, not localized, growth (branching), without a distinct meristem; most cells of thallus are capable of division

Digitate – a blade partly divided, like the digits of a hand

Dimorphic – having two forms

Dioecious – two-households or having male and female reproductive organs on separate algae; unisexual

Diphasic – with two phases in the life history

Diploid – having twice the basic number of chromosomes, in pairs

Diplobiontic – having two free-living phases in life history, one haploid, the other diploid

Discoid – disc-like; in the form of a disc; circular in outline

Discoidal chloroplast - chloroplast having a disc-like or circular outline

Dissected – divided into a number or parts; cut deeply into a number of narrow segments; said of blades

Distal – away from the base or point of attachment; the converse of proximal

Distichous – with branches arranged in two rows on opposite sides of an axis; bracnches may be alternate or opposite, their regular arrangement suggesting a feather; a synonym for pinnate and two-ranked

Distribution – the partition of algae over the world according to their needs of growth, temperature, etc.

Distromatic – composed of two cells in thickness

Division – a major group of algae representing a separate and mutually related evolutionary line

Ecad – a morphological variant of an alga produced in response to a particular habitat that modifications not being heritable; an environmentally induced form

Ecophene – a morphological form of an alga representing a response to the environment and not genetically fixed; an ecad

Ectocarpoid – having a structure that resembles the thallus of Ecotocarpus; said of small non-descript thalli that comprise erect, branched filaments bearing elongate or conical plurilocular organs

Elongate – greater in length than width; stretched out

Embedded – imbedded, immersed or surrounded

Emergent – a raised outgrowth

Endophyte – an alga growing within the tissues of a host plant but not necessarily being parasitic

Endozoic – an organism living in the cells or amongst the tissues of an animal

Ephemeral – an alga that completes its life cycle in a short time

Epilithic – growing attached to an inorganic substratum, such as rocks, stones, etc

Epipelic – living on (or in) fine sediments, namely mud or sand; also growing on muck

Epiphyte – a non-parasitic alga growing on the surface of another

Epithallial cell – a cell formed outwardly from either a basal cell or a subepithallial initial

Extinction depth – the maximum at which a group of alga occur in the sublittoral lying near but above the theoretical depth of compensation; the lower limit of algal vegetation in the sublittoral

Fascicle – a cluster or bundle; a dense cluster of branches or branchlets; crowded in bundles, often parallel to the supporting axis

Fertile – bearing or with reproductive structures

Filament – an alga or branch composed of a linear group of cells joined at their wall; also a chain of cells forming a hair-like strand

Fleshy – succulent, soft and smooth in texture; somewhat cartilaginous; not slimy nor gelatinous; firm

Flora – a treatise or listing of algae from an area or period

Floristic – with reference to a flora or the assemblage of algae and their geographic distribution in a specific area

Foliaceous – leaf-like, broad and flat; having the texture or shape or a leaf

Forciate – having pincher-like shapes, like forceps

Four-ranked – four branches produced at a single node, each separated by an angle of 90 degrees

Free-floating – not attached but floating at or under the surface of water, pelagic, planktonic

Frond – a leaf-like or erect portion of a thallus; often used to define the entire erect portion of a foliaceous or foliose thallus; that pat of the thallus other than the attachment structure

Fucoid – a reference to algae that resembles Fucus or other rockweeds

Fucosan vesicle – small, refractive vesicles present in the cells of brown algae containing fucosan, which demostrates tannin-like properties; also called physodes

Fucoxanthin – the predominant brown carotenoid pigment within the chloroplasts of the Phaeophyceae; also found in members of the Chrysophyceae, Bacillariophyceae and Prmnesiophyceae

Gelatinous – slimy and jelly-like; resembling gelatin or being viscous

Generation – one of the two phases (gametophyte or sporophyte) in the life history of an alga

Geniculum – the uncalcified segment or joint between two successive segments of an articulated coralline alga

Gland cell – special, usually highly refractive cell occurring in the thallus of some red algae; presumed to either release extracellular compounds or possibly serve as a storage cell; contain various halogenated and other compounds, possibly as a deterrent to herbivory

Globose – spherical or rounded in shape

Hair – a colorless, typically elongate, unicellular or multicellular structure; a unicellular or multicellular filament growing from the surface of the thallus, often decidous; several different types of hairs are distinguished in the Phaeophyceae

Haplobiontic – having a single phase in the life history of an organism

Haploid – having one complete set of chromosomes

Heteromorphic – stages of a diplobiontic life history in which the gametophyte and sporophyte are morphologically different, such as members of the phaeophycean order Laminariales

Heterotrichous – a filamentous system composed of both prostate and erect filaments

Holdfast – the attachment organ of a seaweed

Hook – a hook-shaped clasping branch that can become entangled around a branch of another alga

Host – an organism on which another organism grows; the host providing the substratum for a parasite or epiphyte; an alga that nourishes a parasite

Hyaline – translucent or colorless; thin and transparent

Hydrocolloid – a colloidal substance obtained from seaweeds; mucilaginous material extracted from the cell walls of some algae, especially members of the brown and red algae, and used for its stabilizing and gelling properties in commercial products

Hypothallus – in Rhodophyta, the outermost layer of layers or cells in the crustose alga

Immersed – deeply embedded; embedded within; below the surface; entirely under water

Incurved – bending or curved inwards and upwards toward the main axis

Indeterminate branch – a lateral branch having unlimited growth potential, which often exhibits that same structure and mode of growth as the main axis

Indigenous – original to the country, not introduced; native, not foreign

Inflated – swollen, dilated or bladdery

Intercalary – between the apex and base or between two other reference points such as nodes

Intercalary growth – growth localized at one or more loci between the apex and base

Intergeniculum – the calcified segments between the joints of an articulated coralline alga, which are seperated by noncalcified genicula

Internode – an articulation or that portion of an axis intermediate between two nodes, joints or points of attachment; in a filament , the part of a cell between its end-walls

Iridescense – showing rainbow-like colors; reflacting metallic or the changeable colors of the rainbow; glowing or shining

Irregular branching – branching in no consistent pattern; cells not of the same type throughout; cells of varying shapes and dimensions

Isodiametric – having equal dimensions or diameters

Kelp – a member of the order Laminariales – the more massive brown algae also used to describe the burnt ash produced from members of the Laminariales

Kombu – one of the major seaweed components of the Japanese diet commonly prepared from kelps

Lamina – a Latin word for a blade or a thin plate; also a flat, leafy or blade-like expansion

Laminarin – a food storage polysaccharide in the Phaeophyta principally composed of beta-1, 3-linked glucose residues, with some beta-1, 6 linkages providing a branching polymer; it is soluble in the cell

Lanceolate – lance-shaped; flattened, narrow and tapering towards the base and the apex; shaped like a spear-head

Lateral – at, from, or towards the side; an axis formed as a branch from the main axis or from another lateral axis; often used in the sense of branches or ramifications

Linear – long and narrow, with parallel margins; slightly broader than filiform

Lithophyte – an algae growing on rock or stone

Lobed – a somewhat rounded projection or division

Locule – a small chamber or cavity; a compartment of a plurilocular organ

Macroalgae – large algae readily observed without a microscope

Medulla – the inner colorless tissue of an axis, organ or thallus’ the inner core tissue

Membranous – forming a thin layer, often semi-transparent; a sheet or layer, like a membrane

Meristem – a group or region of cells dividing rapidly and initiating growth

Meristematic – an adjective for meristem, referring to a region of cell division

Microalgae – small algae only observed with a microscope

Microthallus – the small inconspicuous phase in the life history of an oganism, alternating with the macrothallus

Midrib -  the thickened longitudinal axis of a flattened branch or blade; a vien- or rib-like structure running up the middle of a blade

Midvein – a usually delicate median line of cells; the blade is thicker through this region than on either side

Minute – a Latin word for very small, inconspicuous or fine

Monoecious – of one household; with male and female reproductive structures born on the same thallus

Mucilage – mucus or a watery sticky substance from seaweeds that contains protein and polysaccharides and its similar to an alga gum

Mucilaginous – slippery and slimy; secreting mucilage; mucilage-like

Multiaxial growth – having a medulla with a central core of several parallel longitudinal filaments, each with its own apical cell; describing a thallus construction where the primary axis consists of parallel aggregate filaments

Multinucleate – with few to many nuclei in the cell or coenocytic thallus

Multiseriate filament – a filament more than two cells wide

Myrionemoid – said of a thallus that resembles the brown alga

Naturalized – algae not indigenous to a region but so firmly established as to have become part of the flora

Nemathecium – an elevation of the thallus containing reproductive organs

Nerve – fine veins in blades

Node – a joint where two cells meet end to end; the site on an axis from which blades and/or branches arise

Nomenclatural type – that element to which the name of a taxon is permanently attached, whether as a correct name or as a synonym

Obligate – necessary or essential

Oblong – elliptical, blunt at each end, and being two to four times longer than broad

Opportunistic – capable of rapidly occupying newly available space

Opposite – referring to locations in the same transverse line but removed by 180 degrees on an axis

Orbicular – spherical, globose or rounded; a flat body approximately circular in outline, orb-shaped

Organ – a portion of a thallus specialized for some function

Ovate – oval in outline; broadest below the middle; having the outline of a hen’s egg

Palmate – flattened and lobed or divided like the palm of a hand; hand-shaped

Panduriform – shaped like a violin

Parenchymatous construction – structure composed of a mass of cells produced by division in two or three dimensions

Parietal – born on or near the side walls, outer or peripheral

Pectinate – branches pinnatifid or having narrow close-set divisions like the teeth of a comb

Perennial – an alga living for more than one year and with most of its tissues remaining intact from year to year

Perforate – to be filled with holes; a pattern or series of holes; pierced through

Perforated plate chloroplast – an elongated chloroplast with parallel or roughly parallel sides and being filled with a series of holes, like a slice of Swiss cheese

Periaxial cell – one of a number of cells cut off from and surrounding an axial cell; also referred to as a pericentral cell

Pericarp – a haploid sterile layer that surrounds the cystocarp in some Florideophycidae

Periclinal – parellel to the surface

Peripheral – pertaining to an outer region, surface or margin

Perithallium – central tissue of a crustose thallus, produced inwardly by an intercalary meristem

Phaeophycean hairs – colorless, endogenous, uniseriate filaments having a basal meristem responsible for elongation; occurring in many orders of the Phaeophyta

Phaetophyta – a division of multicellular algae possessing the brown accessory pigment fucoxanthin along with chlorophyll a and c and storing excess photosynthate as chrysolaminarin and mannitol

Phenology – the sequence of events; seasonal changes in organisms; the study or ecording of periodic phenomena, usually in relation to abiotic factors

Photic zone – depth of water above the compensation depth

Phycology – the study of algae, equivalent to and replacing the older term algology

Phytogeography – geographic botany, the science of plant distribution

Pigment – a colored substance within cells; in algae, generally concentrated in chloroplasts

Pinnate – a synonym for pinnate branching or being arranged like the plumes of a feather

Pit connection – a structure providing cytoplasmic continuity through adjacent cell walls

Plastid – a membrane-bound cell organelle, mostly pigmented but may be colorless

Pleomorphic life history – having more than one form in the same life history, with taxa having previous taxonomic delineations

Ploidy – the number of complete sets of chromosomes in a cell

Plurilocular organ – a reproductive structure in the Phaeophyta having several to many small chambers or compartments divided by septa

Pluriseriate – being more than two cells wide

Polysiphonous – referring to a construction characteristic especially of the Rhodomelaceae in which a simple ring of cells is produced, by longitudinal segmentation, around every cell of a primary uniseriate filament, the central or axial cell; having many siphons or pericentral cells

Proliferous – bearing offshoots; producing many adventitous branches or branchlets as offshoots

Propagation – increase in umber of individuals by vegetative reproduction

Propagule – a multicellular, usually modified, vegetative branch that detaches and propagates a new thallus

Protuberance – a knob-like outgrowth from a crustose thallus; a projection

Pulvinate – cushion, cushion-shape, flattened pads or pad-like

Pustular – like a swelling

Pyrenoid – an organelle in or extending from the chloroplast and associated with reserve foood accumulation

Quadripartite – in four parts

Ralfsioid – said of a thallus that resembles the brown algal genus Ralfsia

Receptacle – a fertile area on which gametangia or sporangia are born in the Fucales and Corallinales

Recurved – bent back away from the main curve of the axis

Reserve – accumulated storage from photosynthesis that can be utilized for respiration and growth

Reticulate – netted, or to divide or construct so as to form a net-work; also net-like or latticed

Rhizoid – a downward growing filament from a surface cell of a thallus that either thickens the axis or functions in attachment of the alga to the substratum

Rhodophyta – the red algae, a division of algae possessing the accessory pigments phycoerythrin-r and phycocyanin-r, lacking any flagellated cells and storing excess photosynthate as rhodophycean starch

Saccate – pouched, ballon-shaped, or appearing like a sack

Saxicolous – growing attached to rock

Seasonal annual – an annual occurring during a specific season of the year

Secund – arranged along one side of an axis, like a comb

Seaweed – a macroscopic marine algae easily observed with the unaided eye

Segmented – divided into segments or joints; articulated as in Corallina

Seirospore – a spore produced by a seriosporangium; a chain of think-walled cells

Serrate – toothed like the edge of a saw

Sexual generation – the stage that bears the sexual organs and produces gametes

Siphon – a tube; in Chlorophyta, used to describe an alga having a tubular and acellular structure lacking cross-walls; also used to delineate a large, multinucleate cell of certain red algae

Siphonaceous – relating to green algae that are tubular, multinucleate and not divided into cells by cross walls

Sorus – a group or cluster of superficial reproductive structures

Spermatangium – in Rhodophyta, a cell whose contents differentiate into a spermatium, the male gamete

Spherical – in the shape of a sphere or globe; ball-shaped; rounded

Spore – a single reproductive cell the fate of which is to germinate or die

Sporangium – a cell whose contents divide up to form motile or non-motile spores. Spores remain for some time within the sporangium before they are set free

Sporophyte – the diploid generation in an alga’s life cycle that produces spores

Stellate chloroplast – a star-shaped chloroplast with radiating lobes

Stripe – a basal stalk-like portion of the thallus

Strap-shaped – band-shaped, like a belt

Substratum – the layer or material to which an organism attaches itself; any surface upon which an alga grows

Tendril – a twining or clasping organ or curled or twisted branch that may entangle a branch of another organism

Terete – round or circular in cross sectional view

Terminal – at the tip or apex; born at the free end or pertaining to the extremity

Tetrasporangium – asporangium in which four spores are usually produced by reduction division, meiosis

Tetrad – a group of four cells formed by two divisions of a spore mother cell

Tetraspore – a single spore of a group or four in a tetrasporangium, usually produced by meiosis

Trichoblast – a simple or branched filament, pigmented or colorless, arising exogenously at the apices of thalli in the family Rhodomelaceae

Tubular – in the form of a tube, being hollow and cylindrical or pipe-like

Tuft – a cluster of filaments, branches or branchlets attached at a single basal point or arise close together at the base

Uniaxial construction – having an axis composed of a single filament

Unicell – an organism consisting of a single cell

Uniocular sporangium – a single celled sporangium containing many spores; reproductive structure of brown algae in which the spores are produced in a single chamber, by meiosis

Uniseriate – in a single longitudinal series, row or file; one cell or loculi wide; cells arranged in one row

Vegetative – to do with cells or tissue produced by mitosis and not associated with any form of sexual reproduction

Vegetative propagation – formation of a new thallus by the separation of part of a parent thallus, by propagules or often occurs by breakage without the formation of special reproductive structures

Whorled – surrounding an axis or branch in a ring; one or several branchlets radiating from the axis at the same level

Wrack – a tangle of seaweeds on the seashore; often used as a common name for fucalean seaweeds