Marine Plants of the Texas Coast

Glossary

185 glossary of Selected Terms This glossary provides definitions of many of the more common terms used in keys to various groups of marine algae and coastal plants. it is by no means exhaustive and includes some terms that are not used in this text but may be useful in further study. abiotic. not biotic; referring to the physical and chemical components of the environment . acuminate. Pointed. alga (algae; adj. = algal). a photosynthetic, nonvascular organism that reproduces without multicellular jacketed male and female structures. alternate branching. Branching along two sides of the stalk, alternating at different levels or positions. amorphous. lacking distinctive morphology; without defined external structures. anastomoses. Cross connections. anatomy. The internal structure of an organism. annular. ringlike in structure; forming a ring, often as constrictions alternating with ridges. anterior. in the frontal position; opposite of posterior. antheridium (antheridia). Male reproductive structure that produces spermatia. anticlinal. radiating outward from the center. apex. Distal end; outer tip; uppermost point; summit. apical cell. The embryonic cell at the apex of a thallus. apical depression. a pitlike cavity at the tip of a branch. appendage. an outward extension. articulate. Jointed. asexual. referring to a reproductive process unrelated to the fusion of genetic material. assimilators. erect, photosynthetic units of a thallus. asymmetric. showing a lack of symmetry; uneven. attenuate. tapering. author(s). Person(s) who described a given species, whose name(s) appear(s) after the latin generic and specific epithets; the last part of the complete scientific citation of an organism. authority. Person with expertise (e.g., in a given taxon or group), not to be confused with the author(s) of a species. auxiliary cell. in most red algae, a cell of the carpogonial filament or a related filament 186 g l O S S A r y that fuses with the carpogonium or an outgrowth of the carpogonium and may subsequently give rise to the gonimoblasts. axial. Pertaining to the primary or central filament, the central core. axil. angle formed between a branch and the axis or main branch from which it arises. axis (axes). Main stem or major branch; central line on which other parts are regularly arranged; the stemlike stalk. basal. toward the base or region of attachment. basipetal. referring to growth toward the base. benthic. attached to a definite substrate or anchored in sand or mud. bilateral. referring to a two-sided (opposite) arrangement in reference to a center line. biogeography. The study of the geographical distribution of organisms. biotic. Pertaining to living organisms. bipinnate. twice-branched, with both primary and secondary branches pinnately divided. biseriate. in two rows. bispore. one of two spores borne in pairs. bladder. a hollow, inflated, gas-filled tissue that enables some algae to float or remain erect. blade. leaflike structure of an alga, often termed “frond”; leaf of a seagrass. brackish water. Part seawater and part freshwater; diluted seawater. branch. Main lateral appendage of the axis. branchlet. smaller projection off a main axis or larger branch. bulbous. shaped like a bulb; having a swollen aspect. caespitose. in tufts. calcareous. encrusted with lime (calcium or magnesium carbonate). calcification. Deposition of calcium carbonate within, between, or on cell walls. calcified. having lime deposits (calcium carbonate, a chalklike substance) within or on the plant; heavily calcified plants appear stonelike in texture. capitate. having a headlike end (with a necklike constriction). carpogonial branch. specialized internal filament terminating in a carpogonium. carpogonium. The female sex organ in the red algae. carposporophyte. a mass of tissue derived from a diploid zygote (fertilized carpogonium ) and giving rise to carpospores. cartilaginous. hard and tough, often shiny. central axis. The filament in the thallus of some red algae that gives rise to all other cells of the thallus; often visible in cross section as a single centrally located cell. cervicorn. referring to dichotomous branching with one arm of the dichotomy suppressed . cf. Compared with; similar to but not quite the same as. character. feature used in taxonomy; one of the attributes that makes up or distinguishes an organism or individual. chlorophyll. Green photosynthetic pigment. chloroplast. Membrane-bound structure within the cell cytoplasm containing chlorophyll (green) pigments. g l O S S A r y 187 chromatophore. Pigmented structure within the cell cytoplasm. class. Group of related organisms forming a category ranking above order and below phylum (name ending in “phyceae”). classification. systematic arrangement in hierarchical groups or categories according to evolutionary (phylogenetic) relationships. clathrate. latticelike; perforated. clavate. Club...