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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta – Order Ceramiales
Thallus erect, decumbent or prostrate, much branched laterally, subdichotomously or with whorl branchlets, with 1–8 periaxial cells from each axial cell, ecorticate or corticated by rhizoidal filaments, adventitious filaments or adherent small-celled filaments. Gland cells present or absent. Growth apical; synchronous laterals present in Griffithsia.
Reproduction: Gametophytes dioecious or occasionally monoecious; procarpic. Carpogonial branches 4-celled, with or without a separate supporting cell, borne on axial or periaxial cells or filaments, in some taxa with a sterile group on the supporting cell; supporting cell usually producing an auxiliary cell post-fertilization. Fusion cell present or absent, the carposporophyte naked (or with a loose involucre), developing gonimolobes with all cells, terminal cells, or chains of cells forming carposporangia. Spermatangial initials on outer cells of periaxial filaments or in specialised clusters or heads.
Tetrasporangia sessile or shortly pedicellate, solitary or in small clusters on periaxial cells or filaments, on cortical rhizoids or filaments or on outer cortical cells, tetrahedrally or cruciately/decussately divided, rarely dividing to octosporangia; polysporangia and propagules present in a few genera.
Mixed phase plants, with tetrasporangia and gametangia on the one plant, occasionally occur in some taxa.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Taxonomic notes: The Ceramiaceae is a large family, well represented on southern Australia coasts with some 22 tribes, 65 genera and 159 species (several other species are known to occur but have not been adequately collected). It is distinguished by the uniseriate branches often with periaxial (but not pericentral) cells and the naked carposporophytes and tetrasporangia.
The following key to the tribes of Ceramiaceae should be used with some caution. While some tribes are characterised by vegetative features, in others knowledge of reproductive structures, especially of the female system, is essential. Some genera also do not fit clearly into the tribe in which they are currently placed.
References:
DUMORTIER, B.C.J. (1822). Commentationes Botanicae. Observations botaniques, dédiées à la Société d'Horticulture de Tournay. (Tournay.)
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
KEY TO TRIBES OF CERAMIACEAE
1. Cortication absent or by lax to dense rhizoidal filaments of elongate cells usually arising from the basal cells of lateral branches/-lets at least several cells below the apices, when present usually covering the axial cells with discrete filaments | 2 |
1. Cortication from usually close to apices, nodal or complete, by closely appressed filaments, appearing pseudoparenchymatous, cortex generally bare of external filaments with most outer cells short and isodiametric | 19 |
2. Whorl-branchlets opposite or whorled on indeterminate axes, in some taxa obscured by dense rhizoidal cortication | 3 |
2. Branchlets alternate or irregular throughout, not obscured by rhizoidal cortication, with no more than slight opposite or whorled arrangement [except for involucral branchlets below carposporophytes or synchronous whorls in some Griffithsieae, e.g. Halurus, and also Ochmapexus (Radiathamnieae)] | 12 |
3. Main axes and branches heavily corticated by lax descending rhizoids, whorl-branchlets irregularly much branched and adjacent whorls overlapping, whorls often indistinct | 4 |
3. Main branches not or relatively slightly corticated, with clearly defined whorls (or opposite pairs) of whorl-branchlets closely adjacent or clearly separated | 6 |
4. Branching opposite on indeterminate axes, irregular in whorl-branchlets; gland cells present. Carpogonial branches scattered on cells of determinate or indeterminate branches, carposporophytes discrete, compact; tetrasporangia cruciately or decussately divided | WARRENIEAE |
4. Indeterminate axes and branches with 2 opposite whorl-branchlets (obscured behind apices) or (4–) 5 whorl-branchlets; gland cells absent; Carpogonial branches on successive axial cells or on pilose outer cortical filaments; carposporophytes incorporating whorl-branchlet filaments or discrete; sporangia tetrahedrally divided | 5 |
5. Indeterminate axes and branches with (4–) 5 irregularly branched whorl-branchlets per axial cell. Carpogonial branches borne on successive axial cells near apices of indeterminate branches; carposporophytes incorporating terminal parts of fertile branches, with gonimoblast filaments intermingled with sterile whorl-branch filaments | WRANGELIEAE |
5. Indeterminate axes and branches with 2 opposite, alternately branched, whorl-branchlets per axial cell, opposite branchlets rapidly obscured by dense cortication. Carpogonial branches borne on branched pilose outer cortical filaments; carposporophytes discrete, compact | LAS IOTHALIEAE |
6. Whorls of whorl-branchlets usually closely adjacent on the indeterminate branches, forming more or less linear branches with even contours; gland cells present or absent | 7 |
6. Whorls of whorl-branchlets clearly separated on the indeterminate branches, giving irregular or moniliform contours; gland cells usually present, parallel or angled to the bearing cell and broadly attached to it | 8 |
7. Whorl-branchlets in whorls of 3 or 4, formed in spiral or opposite sequence | CROUANIEAE |
7. Whorl-branchlets in whorls of 5 or 6, formed alternately or in opposite groups of 3 | DASYPHILEAE |
8. Thalli usually | SPHONDYLOTHAMNIEAE |
8. Thalli usually | 9 |
9. Thalli usually ecorticate; gland cells absent or on short, | 10 |
9. Thalli with lower axes corticate with rhizoids or ecorticate; whorl-branchlets usually not distichously branched (except in Ballia); gland cells absent or present but not on short | 11 |
10. Gland cells present, on short, | ANTITHAMNIEAE |
10. Gland cells absent; whorl-branchlets always distichous on axes, simple or with few branches; carpogonial branches on opposite, shorter, whorl-branchlets; tetrasporangia mostly terminal on whorl-branchlets, irregularly tetrahedrally divided. | GYMNOTHAMNIEAE |
11. Thalli mostly relatively large ( | PTEROTHAMNIEAE |
11. Thalli mostly relatively small, | HETEROTHAMNIEAE |
12. Cells relatively small, mostly < 150 µm in diameter (apart from older axial cells), uninucleate or multinucleate; propagules absent; procarps subapical on short or several-celled axes or on intercalary cells of normal axes | 13 |
12. Cells large, lower cells usually over (100–) 150 m in diameter (except some Monosporeae), multinucleate; procarps subapical on short axes | 17 |
13. Thalli small (less than 2 cm high), ecorticate; propagules present (Monosporeae) or absent; procarps on subapical cells of short branches or on the basal cell of a short axial branch, with single auxiliary cells and carposporophytes | 14 |
13. Thalli small to large, (1–) | 15 |
14. Thalli small, | SPERMOTHAMNIEAE. |
14. Thalli minute (less than 3 mm high), epiphytic on Laurencia, or Caulerpa and other algae; with a single basal cell or complanate multicellular holdfasts; main axes curved, with unilateral laterals from the convex side; cells uninucleate; spermatangia formed directly from branch cells; tetrasporangia tetrahedrally divided | RADIATHAMNIEAE |
15. Thalli small to 20 cm high, ecorticate above and corticated or not on lower axes or branches; apical cell divisions transverse. Carpogonial branches on one of two periaxial (supporting) cells on intercalary cells of indeterminate axes or laterals, with both periaxial cells producing auxiliary cells and "twinned" carposporophytes; procarps without sterile cells; spermatangia on branched filaments or small clusters | CALLITHAMNIEAE |
15. Thalli | 16 |
16. Branch apices usually emergent. Procarps ( | COMPSOTHAMNIEAE |
16. Branch apices usually overtopped by lower branchlets. Procarps on subapical cells of special 3 (–5) celled fertile branches (if 5-celled, the upper 3 cells modified), with the apical and 2 lateral lower sterile cells larger and rounded, with the carposporophyte appearing terminal on short lateral branches, with a lax involucre of short branches from axial cells below the procarp | SPONGOCLONIEAE |
17. Asexual ovoid, | MONOSPOREAE |
17. Propagules absent; lower cells usually more than 200 µm in diameter; tetrasporangia only | 18 |
18. Synchronous lateral branches absent; female axes | BORNETIEAE |
18. Synchronous lateral branches present; female axes 3 cells long, with a subapical carpogonial branch; carposporangia ovoid to clavate, formed from most cells of the carposporophyte | GRIFFITHSIEAE |
19. Branching usually pinnate, with alternate or opposite laterals lying in one plane, usually alternately developed; cortication filamentous to pseudoparenchymatous, irregularly developed on the axial cells | 20 |
19. Branching radial or complanate (pinnate in some Ceramium spp.), cortication from whorls of nodal periaxial cells forming acropetal (and usually basipetal) filaments mostly of short cells closely appressed to the axial cells | 21 |
20. Indeterminate axis cells with 2 or 4 periaxial cells, producing alternate or opposite distichous determinate branches. Tetrasporangia on ultimate, ecorticate branchlets | PTILOTEAE |
20. Indeterminate axis cells with | RHODOCALLIDEAE |
21. Cortication of indeterminate branches complete, consisting of alternating bands of long and short cells, longitudinally and transversely aligned; indeterminate branches bearing lateral or whorled (or single) elongate determinate ramelli with narrow nodal cortication only and bearing tetrasporangia at the nodes | SPYRIDEAE |
21. Cortication of all branches arising nodally, closing completely or leaving a clear gap; elongate determinate ramuli absent; tetrasporangia from periaxial or cortical cells | CERAMIEAE |
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