Glossary for Seaweeds

Antheridium (pl. antheridia):  a structure that produces motile male gametes (sperm). 
Ascoglossan:  referring to the order Ascoglossa (=Sacoglossa), an order of sea slugs (Mollusca: Gastropoda: Opisthobranchia).
Bisexual:  having both sexes.
Blade:  a flattened, leaf-like part of the thallus.
Calcar:  spur subtending a cystocarp.
Carpogonium (pl. carpogonia):  the female sex structure in red algae.
Carpospore:  a spore, usually diploid, produced in the carpogonium. In red algae, it grows into a free-living tetrasporophyte.
Cerata:  dorsal appendages on some opisthobranch mollusks (sea slugs) that contain diverticula of the digestive gland. Serve
    as gills.
Chloroplast:  a cell organelle specialized for photosynthesis, the production of carbohydrates from carbon dioxide, water in the
    presence of light energy.
Coenocytic:  referring to a multinucleate cell, the coenocyte, derived when the nucleus divides but the cytoplasm does not.
Conceptacle:  a fertile cavity, often with a pore.
Cortex:  tissue external to the medulla, often an outer covering, of a blade.
Cryptostomata:   minute cavities in the outer cortex of Fucales containing hairs.
Cystocarp:  a structure in the female gametophyte of red algae consisting of diploid carposporophyte surrounded by
    gametophytic tissue. It may be a pigmented bump with or without an ostiole.
Dichotomous:  branching in pairs. 
Dioecious:  bearing male and female reproductive structures on separate individuals.
Diploid:  having a normal (double or 2n) set of chromosomes.
Discoid:  disk shaped. Usually referring to the shape of holdfasts.
Distichous:  arranged in two rows on opposite sides of an axis.
Distromatic:  having two layers of cells.
Gametangium (pl. gametangia):  a structure that produces gametes.
Euryhaline:  able to withstand a wide range of salinities.
Eurythermal:  able to withstand a wide range of temperatures.
Filamentous:  a row of cells arranged end to end forming a hair-like thallus.
Gamete:  a sexual cell, male or female (e.g., sperm and eggs).
Gametophyte:  the haploid and sexual phase in the life history of an alga; produces  gametes.
Haploid:  having a single set of chromosomes - half the normal number (1n).
Herbivory:  feeding on plants.
Holdfast:  the structure that attaches the alga to its substratum.
Intercallary:  occurring anywhere along the thallus except at the apex.
Intergeniculum (pl. intergenticula):  a calcified segment between the uncalcified joints of coralline algae.
Isomorphic:  having the same shape; looking alike.
Lanceolate:  shaped like a lance; several times longer than wide.
Laminarin:  a polysaccharide carbohydrate energy storage product in Laminaria.
Meristem:  a region of rapidly dividing, undifferentiated cells; an area of growth.
Midrib:  the middle rib of a blade.
Monoecious:  bearing male and female reproductive structures on the same individual.
Monostromatic:  having one layer of cells.
Oogonium:  a female reproductive cell (gametangium) that produces one or more female gametes (eggs).
Ostiole:  a pore.
Ovate:  egg-shaped.
Papilla (pl. papillae):  small rounded or pimple-like projections on a surface
Pericentral:  surrounding central axial cells.
Pinnate:  having similar parts arrange on opposite sides of an axis, like a feather.
Plastid:  a pigmented cell organelle (e.g., a chloroplast which contains chlorophyll). 
Pneumatocyst:  a gas bladder or float of brown algae.
Receptacle:  the inflated tip of a branch that holds conceptacles (e.g. the swollen tip of Fucus).
Rhizoid:  a unicellular or filamentous structure for attachment.
Rhizome:  a horizontal, shoot-producing stem growing within the substrate.
Saxicolus:  growing on rocks.
Spermatangium (pl. spermatangia):  a cell in red algae that produces a single, nonflagellated, male gamete (the spermatium).
Spore:  a motile or nonmotile, asexual reproductive structure.
Sporophyll:  the part of the alga, usually a blade, which bears sporangia, the structure that produces spores.
Sporophyte:  the diploid phase in the life history of the alga; produces spores.
Sorus (pl. sori):  a cluster of reproductive structures.
Stipe:  the stem-like part of the thallus between the holdfast and the blade(s).
Stolon:  a runner growing out of the base of the alga capable of producing offshoots.
Substratum:  the material (such as rock) on which the alga is growing (substrate).
Tetraspore:  a spore, grouped in fours, produced by tetrasporophytes
Tetrasporophyte:  a phase in the life history of red algae that produces tetraspores.
Tertiary:  referring to a third stage.
Thallus:  the body of the alga.
Uniseriate:  having a single row of cells.
Utricle:  the inflated part of Codium that contains plastids.
Vegetative:  not associated with reproductive cells or sexual reproductive capacity.
Zygote:  a fertilized egg cell.

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