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Glossary

Acroblastic:

With branching originating from the apical cell.

Acropetal:

Developing from the base towards the apex: the youngest structures nearest the apex.

Adaxial:

Of lateral organs, the side lying nearest to the main axis, or furthest from it if the organ is deflexed.

Adelphoparasite:

A parasite which is phylogenetically closely linked to its host.

Angular:

With prominent angles, sharply ridged.

Anisogamy:

Sexual reproduction with motile gamete of unequal size; the larger is designated as the female while the smaller is male.

Antheridium:

The male gametangium in oogamus sexual organ.

Anticlinal:

In a direction perpendicular to the circumference/surface of the thallus.

Applanate:

Flattened or horizontally expanded.

Arcuate:

Curved like a bow; crescent-shaped.

Ascocyst:

A sac-like, enlarged cell, usually empty when old.

Attenuate:

Gradually tapering towards a point.

Axil:

The distal angle between a lateral branch, and the axis or organ bearing it.

Basipetal:

Developing from the apex towards the base: the youngest structures are nearest the base.

Bifurcate:

Forked; dividing more or less equally into two.

Bipinnate:

Pinnate branchlets arranged pinnately on the main branch.

Biseriate:

Arranged in two rows (especially of cells in a filament).

Bisporangia:

Sporangia in which two spores are produced.

Bisporiferous:

Bearing bisporangia.

Blade:

the broad, flatted part of the thallus.

Botryoid:

Having the appearance of a bunch of grapes.

Bullate:

Puckered.

Caespitose:

Matted, growing in turf or dense turf-like clumps.

Calcareous:

Impregnated with calcium carbonate.

Calcicolous:

Thrives in areas/habitats rich in calcium; growing on calcareous substrata.

Canaliculate:

Channeled; possessing a long groove.

Capitulum:

A swollen or knoblike tip.

Carposporangium:

A unicellular structure on the parasitic carposporohyte phase of members of the Florideophyceae, which gives rise to non-motile carpospores.

Cartilaginous:

Not easily compressed, yet flexible; like cartilage.

Catenate:

Chain-like.

Cervicorn:

Antler-like; branching one-sided.

Cicatrigenous:

Generated by a scar-cell or basal cells of a trichoblast (Rhodomelaceae).

Clavate:

Club-shaped.

Coenocytic:

Multinucleate and without cross walls.

Complanate:

Structures arranged in a single plane.

Conceptacle:

A cavity just below the surface of the thallus containing reproductive organs.

Convolute:

Rolled or twisted.

Cordate:

Heart shaped.

Cornucopiaeform:

Shaped like a goat’s horn or horn of plenty.

Cortex:

The outer layer of cells or tissue in a thallus, outside the medulla.

Corticated:

Having an outside layer of small cells.

Corymbose:

Having the shape of a cluster flattened transversely to the main axis.

Cruciate:

Divided in the shape of a cross (usually refers to tetrasporangia).

Crustose:

Lying closely and tightly fixed to the substratum.

Cuneate:

Wedge-shaped.

Cymose:

Type of distal branching in which the apices abort successively, growth being continued by laterals in each instance.

Decussate:

Having a branching pattern where paired opposite branches are perpendicular to the previous pair down the main axis.

Deltoid:

Shaped like a triangle.

Dentate:

Toothed.

Determinate:

Fixed or limited in number of parts or growth.

Dichotomous:

Divided or forked into two equal parts.

Diffuse (growth):

Growth in almost any part of the thallus, not localized.

Digitate:

Branched or split like the fingers of a hand.

Dioecious:

Having male and female reproductive structures on separate individuals.

Diplobiontic:

With a life history involving two free-living morphological phases.

Diplohaplontic:

With a life history involving an alternation between a haploid and diploid phase; these phases may be iso- or heteromorphic.

Diplont:

Alga in which the diploid phase is multicellular or dominant, with a cellular haploid phase represented by gametes.

Direct life history:

Reproduction of the same phase of the life history by means of asexual spores or propagules.

Distichous:

Arranged in two vertical rows along opposite sides of an axis.

Distromatic:

Two cell layers thick.

Edentate:

Lacking ‘teeth’ or tooth-like projections.

Endogenous:

Originating from within.

Endophytic:

Growing within the tissue of plants, but not necessarily parasitic.

Endozoic:

Growing within the tissue of animals, but not necessarily parasitic.

Epilithic:

Growing attached to rock (saxicolous).

Epiphytic:

Growing on plants or other algae.

Epizoic:

Growing on animals.

Evesiculate:

Without vesicles.

Excrescenses:

Outgrowths from the surface.

Falcate:

Sickle-shaped.

False hair:

Hair-like, tapering extensions of the filaments, with almost colourless cells, and without a basal meristem.

Fascicle:

A bundle-like cluster.

Fasciculate:

Resembling a fascicle.

Fenestrate:

Possessing window-like or pierced openings.

Filamentous:

Thread-like.

Filiform:

Thread-like; long and slender, and circular in cross-section.

Flabellate:

Having the shape of an open fan.

Flagelliform:

Whip-like; long, thin and tapering.

Flexouse::

Bending or twisting from side to side.

Flexuous:

Axes or branches with zig-zag development, usually with the alternate braches on each side.

Foliaceous or Foliose:

Flat and expanded, resembling a leaf.

Fusiform:

Elongated and tapering towards each end.

Gametangial::

Gamete-producing.

Gametophyte:

The haploid, gamete-producing phase of a life history.

Geniculate:

Bearing flexible (uncalcified) joints.

Globose:

Spherical in form.

Gonimoblast:

A filament developing from the fertilised carpogonium or auxiliary cell, which gives rise to the carposporangia.

Gonimolobe:

Element of a gonimoblast that develops from a single initial cell and gives rise to caroposporangia: usually several are formed sequentially in cystocarp.

Hamifera:

Hook-like organs or outgrowths.

Haplobiontic:

Having a life history with a single phase, which may be either haploid or diploid.

Haplont:

Alga in which the dominant phase is a haploid gametophyte followed by a unicellular diploid zygote.

Hapteron:

An organ or outgrowth of attachment.

Heteromorphic:

Having dissimilar morphological forms.

Heterotrichous:

Consisting of both prostate and erect filaments.

Holdfast:

A basal attachment organ.

Hypacroblastic:

Origin of laterals from cells below the apical cell, from either the full length of the parent cell (hemiblastic) or from a subdivision of the parent cell (meriblastic).

Hyphae:

Elongate filaments (e.g. in the medulla of kelps).

Hypobasal:

Below the basal cell layer (usually in crustose algae).

Hypogenous:

Developing or growing on a lower surface; in some red algae referring to a position below the procarp-bearing cell.

Indeterminate:

Unrestricted or unlimited growth or number of parts.

Indusium:

A cellular cover over the sporangia.

Intercalary:

Situated between the apex and the base, or between nodes.

Intergenicula:

The calcified segments of the articulated Rhodophyta.

Isodiametric:

With vertical and horizontal diameters equal.

Isogamous:

Having morphologically similar gametes.

Isomorphic:

Having morphologically similar plants.

Laciniate:

Fringed; torn into finger-like or lobed segments.

Lamina:

Blade.

Laminate:

Layered.

Lanceolate:

Long and narrow, tapering on both ends, with the broadcast part approximately one third the length from the base.

Lappet:

A flap or fold.

Lateral:

to the side of, or term used for a side-branch.

Lenticular:

Lens-shaped.

Ligulate:

Strap-shaped.

Locule:

A compartment of a reproductive organ.

Medulla:

The central region of a thallus, inside the cortex.

Meristem:

A region of the thallus where the cells are actively dividing.

Meristoderm:

A superficial layer of dividing cells covering the thalli of Laminariales.

Moniliform:

Resembling a string of beads.

Monoecious:

Having both male and female reproductive structures on the same individual.

Monopodial:

A mode of development where the main axis continues growth and stays dominant over the lateral axes: the successive lateral branches which are given off are smaller than the main axis.

Monosiphonous:

Having a single row of cells without cortication.

Monosporangium:

A sporangium which releases a single spore which may be uni- or multinucleate.

Monostromatic:

Composed of a single layer of cells.

Mucro:

A sharp tip.

Mucronate:

Abruptly terminating in a sharp point.

Multiaxial:

With a type of thallus construction that comprises numerous axial filaments.

Multiseriate:

More than one cell wide:.

Multistratose:

Composed of many layers.

Nemathecium:

Reproductive sorus, projecting somewhat from the surface.

Obpyriform:

Inverted pear-shaped.

Ocellate:

Possessing spots; in some algae referring to a dense cluster of apical branchlets.

Oogomy:

The union of a motile or non-motile male gamete with a large non-motile female gamete.

Oogonium:

The female gametangium in oogamous sexual reproduction.

Orbicular (Orbiculate):

Almost circular or spherical.

Orthostichous:

Arranged in a straight, vertical row.

Ostiole:

A pore-like opening in some reproductive organs.

Ovate:

With the outline of an egg, the broader part towards the base.

Ovoid:

Egg-like, the thickest part towards the base.

Palmate:

Fan-shaped; like an open hand.

Papilliform:

Resembling a nipple-like projection.

Paniculate:

Arranged as loose, irregularly clustered branches.

Paraphyses:

Sterile cells or filaments associated with reproductive organs.

Parasporangium:

A reproductive structure producing many spores, but not homologous with a tetrasporangium.

Parenchymatous:

Composed of solid, two or three-dimensional tissue, usually comprising thin-walled, isodiametric cells.

Parietal:

Occurring against the wall of a cell.

Parthenogenesis:

Production of an individual from a single, unfertilised gamete.

Pectinate:

Comb-shaped.

Pedicellate:

Having or supported by a small stalk.

Peltate:

A rounded lamina with a stalk arising from near the centre of its under-surface.

Percurrent:

Occurring along the entire length; extending from base to apex.

Periaxial:

Immediately surrounding the axis or axial cells (e.g. in Ceramiaceae).

Pericarp:

Distinct sterile structures surrounding carposporophyte.

Pericentral:

Immediately surrounding, and derived from, central cells (e.g. Rhodomelaceae).

Periclinal:

Parallel to the surface or circumference.

Phaeophycean:

hair: A uniseriate filament without plastids with a basal meristem (in the brown algae).

Pinnate:

Structures in two rows in opposite sides of an axis, like a feather.

Planoconvex:

Flat on one side with a bulging curvature on the other.

Plastid:

A body in the cytoplasm containing the photosynthetic pigments.

Plectenchymatous:

Consisting of more or less densely interwoven filaments.

Plurilocular:

With many chambers (or locules) each producing a spore or gamete.

Polysiphonous:

Having a number of longitudinal rows of cells surrounding and cut off from a central filament, giving rise to a many-siphoned appearance (see siphonaceous: mainly in the family Rhodomelaceae).

Polysporanguim:

A sporangium containing more than four spores.

Polystichously:

Arranged in many series or ranks.

Polystromatic:

With three or more layers of cells.

Procumbent:

Trailing along the substrate; prostrate.

Propagule:

A multicellular structure that functions in asexual (vegetative) reproduction.

Proximal:

Situated towards the point of attachment or base of the thallus.

Pseudohair:

Particularly thin or colourless tip of filament.

Pseudoparenchymatous:

Comprising a system or network of closely packed filaments having the appearance of parenchymatous tissue.

Pulvinate:

Cushion shaped; or having a convex surface.

Punctae:

Dots or marks on the thallus.

Pyriform:

Pear-shaped.

Radial:

Occurring uniformly around a central axis.

Ramuli:

Small or secondary branches.

Receptacle:

The swollen end of a branch bearing reproductive organs.

Rectilinear:

Arranged in straight rows.

Repent:

Creeping along the substrate; prostrate.

Reticulate:

Resembling or forming a network.

Rhizines:

Slender thick-walled filaments found in the medulla of certain members of the Gelidiales.

Rhizoid:

An attaching or absorptive structure made up of one to few undifferentiated cells.

Rhizomatous:

Having a root-like structure (rhizome) running along the substratum, giving rise to attachment structures below and free upright parts.

Rhomboid:

Having sides of equal length, but not a square.

Rugose: :

Having a rough, wrinkled or ridged surface.

Saxicolous:

Growing attached to rock.

Schizogenic:

cavity:

Hollowing of a thallus, caused by separation of the cells.

Secund:

Branching only on one side of an axis.

Serrate:

Having a notched or toothed appearance.

Sessile:

Attached directly, without a stalk or stipe.

Simple:

unbranched or undivided.

Siphonaceous:

Cells tubular, multinucleate, and with no cross walls.

Sorus:

A dense cluster of sporangia or gametangia.

Spermatia:

Non-motile male gametes in the division Rhodophyta.

Spiniform:

Spine-like.

Sporangia:

Spore-producing cells or structures.

Sporangial:

Pertaining to asexual spore production.

Sporophyll:

A fertile, spore-producing blade.

Sporophyte:

The diploid, spore-producing phase of a life history.

Stellate:

Star-shaped.

Stephanokant:

With a crown of flagella.

Stichidium:

A specialised branch containing tetrasporangia or spermatangia (in the Rhodophyta).

Stipitate:

Borne on a short stalk termed a stipe.

Stolon:

A horizontal stem-like structure which gives rise to upright parts at various intervals.

Subdichotomous:

Tending towards or mostly dichotomous.

Sublittoral:

fringe:

The upper portion of the sublittoral zone occasionally uncovered by extreme low tide.

Subtidal:

That region which is always submerged; usually only applies to the inshore areas.

Supralittoral:

The area above the spring high water mark, or the ‘splash’ or ‘spray’ zone.

Sympodial:

growth:

A mode of development where the main axis is continually replaced by lateral axes i.e. with each branching the lateral takes over from the then ‘main’ axis.

Terete:

Cylindrical and circular in cross-section.

Tetrahedral:

Having four plane faces at approximately 109.5° apart; in tetrasporangia, dividing into four three-sided pyramids, the apices meeting in the centre.

Tetrasporangium:

A sporangium found in red algae and Dictyotales of the brown algae, containing four spores.

Thallus:

The relatively simple body of a plant (in this case a seaweed).

Tortuous:

Twisted.

Torulose:

Cylindrical, but with bulges or contractions at intervals.

Trichoblast:

A laterally-produced, colourless, simple or branched filament found in algae belonging to the family Rhodomelaceae, also associated with reproductive structures in that group.

Trichogyne:

A hair-like structure or extension of the female gametangium which intercepts the male gametes (Rhodophyta).

Trichothallic:

Growth (in the Phaeophyta) in which the site of cell division is at the base of a filament or groups of filaments.

Truncate:

Appearing to be cut off at the top; ended abruptly as if cut off.

Tubercle:

a small, rounded, wart-like protuberance.

Turf:

A dense layer of tightly-packed upright plants.

Umbilicate:

Having depressions resembling navels or dimples, often associated with holdfasts.

Undulate:

Having wavy margins.

Uniaxial:

Having a single central axis or filament.

Unilocular:

With a single chamber (or locule).

Uniseriate:

Consisting of a single series or row.

Unistratose:

Consisting of a single layer of cells.

Urceolate:

Urn-shaped.

Utricle:

A filament or tube which is dilated or swollen at its end or apex.

Verrucose:

Covered with warts or wart-like projections.

Verticillate:

Bearing successive whorls of three or more branches/branchlets per node.

Vesicular (Vesiculate):

Having the form of a vesicle i.e. a small bladder-like sac.

Zonate:

Having a pattern of meiotic cell division where the spores are cut off in three parallel planes, giving a stacked appearance (in tetrasporangia); divided into zones.

Zooid:

A motile flagellate reproductive cell, gamete or spore.

Zooidangium:

A zooid-producing structure.

Zoosporangium:

A sporangium producing asexual motile flagellate spores.

 

This glossary is reproduced from Stegenga et al. (1997).

Citing this publication:

Anderson RJ, Stegenga H, Bolton JJ. 2016. Seaweeds of the South African South Coast.
World Wide Web electronic publication, University of Cape Town, http://southafrseaweeds.uct.ac.za; Accessed on 25 April 2024