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Electronic Flora of South Australia
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Electronic Flora of South Australia Genus Fact Sheet

Genus CYSTOPHORA J. Agardh 1841: 3; 1848: 238, nom. cons.

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Thallus usually 20 cm-2 m long, with usually a single, long, axis from the discoid-conical holdfast. Primary axes compressed in most species, ovoid in transverse section or terete in some, flexuous, bearing alternately distichous laterals from the face or the margins of the axis; secondary and usually tertiary axes, similar in structure to the primary axes, arise adaxially in the axils of laterals. Laterals of determinate growth, simple, distichous, tristichous, radially or irregularly branched, with compressed, terete or irregularly swollen ramuli, with or without a recognisable rhachis. Vesicles present or absent, usually replacing the lower 1–2 ramuli of laterals. Growth from a three-sided apical cell in an apical depression. Structure with a central medulla of elongate cells and hyphae, and a cortex of isodiametric cells with a surface, phaeoplastic, meristoderm increasing the cortex.

Reproduction: Thalli usually monoecious, occasionally dioecious. Receptacles developed from ends or most of the ramuli (or the, whole lateral), compressed to terete or irregularly swollen, with conceptacles in rows on the margins of compressed receptacles, or along terete receptacles, or irregularly scattered; conceptacles usually bisexual, occasionally unisexual; oogonia with a single egg.

Lectotype species: C. retroflexa (Labillardière) J. Agardh (see Womersley 1964, p. 55).

Taxonomic notes: Cystophora is the largest genus of Fucales on southern Australian coasts, with 6 species in New Zealand (two not found in Australia). The genus is endemic to Australasia, and was monographed by Womersley (1964) and the anatomy of several species discussed by Nizamuddin (1964c). Recently Klemm & Hallam (1987) have shown that the axes are not sympodially developed, but flexuous due to alternately and largely one-sided divisions of the apical cell. How new secondary axes arise in the axils of laterals is still unclear. Sympodial branching is also credited to Cystoseira (see Roberts 1967, p. 349) and needs to be investigated further. Growth is from a three-sided apical cell, and the structure of the thallus is uniform in all species investigated (Nizamuddin 1964c), hence these details are not repeated for each species. The conceptacles of most species are bisexual, but the antheridia vary from few, in small clusters and often near the ostiole, to plentiful over most of the conceptacle surface; simple paraphyses are also present in bisexual and female conceptacles.

The only species of Cystophora recorded from outside Australasia is C. fibrosa Simons (1970, p. 1, figs 1,2) from Cape Agulhas, South Africa. Early collections of G.F. Papenfuss (in 1937) and M. Pocock in 1939 and 1940, in ADU, had been designated C. capensis. C. .fibrosa possesses a slightly compressed axis from which branches arise bilaterally and alternately; the axis is probably monopodially developed, not sympodially as Simons stated, since it is not flexuous. It also lacks the single axis of Cystophora with laterals of limited growth with new flexuous secondary axes arising in the axils of the laterals. C. fibrosa is not a Cystophora, but appears better placed in Cystoseira; detailed studies are needed to establish its affinities, and if justified a new name will be needed since Cystoseira fibrosa (Hudson) C. Agardh is a distinct species.


AGARDH, J.G. (1841). In historiam algarum symbolae auctore. Linnaea 15, 1–50, 443–457.

AGARDH, J.G. (1848). Species, Genera et Ordines Algarum. Vol. 1. (Gleerup: Lund.)

KLEMM, M.F. & HALLAM, N.D. (1987). Branching pattern and growth in Cystophora (Fucales, Phaeophyta). Phycologia 26, 252–261.

NIZAMUDDIN, M. (1964c). The anatomy and life history of Cystophora, Acrocarpia and Caulocystis (Fucales). Bot. Mar. 7, 42–63.

ROBERTS, M. (1967). Studies on marine algae of the British Isles. 3. The genus Cystoseira. Br. phycol. Bull. 3, 345–366.

SIMONS, R.H. (1970). Marine algae from southern Africa. 1. Six new species from the inter-and infra-tidal zones. Repl. S. Africa, Division of Sea fisheries, Investigational Report No. 88.

WOMERSLEY, H.B.S. (1964). The morphology and taxonomy of Cystophora and related genera (Phaeophyta). Aust. J. Bot. 12, 53–110, Plates 1–16.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia


1. Branching from the edges of flattened or ovoid (in cross section) axes, or from opposite sides of terete axes, and with terete to slightly compressed ramuli


1. Branching from the faces of slightly (in C. pectinata, with compressed ramuli) to distinctly compressed or subquadrangular axes


2. Axes strongly compressed, usually 5–15 mm broad


2. Axes ovoid (in cross section) or terete, usually 2–6 mm broad


3. Laterals once pinnate; receptacles flat, broadly lanceolate, 1–3 cm long and 3–8 (–10) mm broad; vesicles spherical, 5–15 mm in diameter I

C. platylobium

3. Laterals much branched; receptacles terete-torulose, drying moniliform, 0.5–2 (–4) cm long and about 0.5 mm in diameter; vesicles absent

C. moniliformis

4. Axes ovoid in cross section, usually 3–6 mm broad and half that in thickness; laterals subfasciculate, receptacles terete to torulose, 0.5–1 mm in diameter; vesicles absent

C. intermedia

4. Axes terete, 2–5 (–7) mm in diameter; laterals openly branched and alternately distichous, receptacles slightly compressed, smooth, 1–2 (–3) mm broad; vesicles sub-spherical, 5–12 mm in diameter

C grevillei

5. Laterals unbranched (rarely once furcate), developing as strongly flattened receptacles 3–6 (–9) cm long and 3–8(4 0) mm broad

C. xiphocarpa

5. Laterals normally branched; receptacles compressed, or terete and smooth to moniliform, or with irregular swellings


6. Laterals pinnately and complanately branched, with rigid ramuli and distinctly compressed receptacles 1.5–4 mm broad


6. Laterals distichously, tristichously, irregularly or radially branched, with rigid to (more usually) moderately to distinctly lax ramuli and terete to slightly compressed receptacles


7. Axes only slightly compressed; laterals pinnate, with wings joining the ramuli and rhachis; receptacles 0.5–1 (–2) cm long, often apiculate; vesicles absent

C. pectinata

7. Axes distinctly compressed; laterals pinnate, without wings; receptacles 0.5–3 cm long; vesicles usually present, subspherical, 3–8 (–10) mm in diameter

C. racemosa

8. Laterals radially branched, with numerous ramuli around the rhachis; vesicles numerous, clustered at base of laterals, replacing numerous ramuli


8. Laterals tristichously, distichously or irregularly branched; vesicles absent, or replacing basal 1 or 2 ramuli of lateral only, or scattered over the laterals


9. Ramuli (receptacles) usually simple, terete, smooth, 1–2 cm long and 1–1.5 mm in diameter; vesicles spherical to slightly ovoid

C. botryocystis

9. Ramuli (receptacles) simple or alternately branched, distantly moniliform, 0.5–2 cm long and 0.4–0.7 (–1) mm in diameter at conceptacles; vesicles elongate-ovoid, tapering at both ends

C. polycystidea

10. Laterals tristichously branched when young, with ramuli becoming somewhat displaced when mature; ramuli slender, 0.2–0.5 mm in diameter; receptacles teretetorulose to moniliform


10. Laterals basally furcate, or complanately, or irregularly, branched; ramuli slender to robust, 0.5–4 mm in diameter


11. Receptacles usually 1–2 (–3) cm long; vesicles normally present, subspherical, 3–6 (–8) mm in diameter, mutic, replacing lower ramuli of laterals

C. monilifera

11. Receptacles 0.5–1 (–1.5) cm long; vesicles usually present, elongate-ovoid with tapering ends, 3–7 mm long and 1–2 mm in diameter, replacing lower branches of ramuli and thus scattered over the laterals

C. expansa

12. Laterals simple or usually basally furcate 1–3 times; receptacles densely clustered on axes, 1–5 (–7) cm long and (1–) 2–3 (–4) mm in diameter, terete to slightly 3-sided, linear or curved or slightly clavate, relatively smooth

C. torulosa

12. Laterals much branched, distichously or irregularly; receptacles usually distant from axes, 0.5–8 cm long and 0.5–2 mm in diameter or broad, terete and torulose to irregularly moniliform, or slightly compressed and smooth


13. Receptacles 2–8 (–10) mm long, terete-torulose


13. Receptacles (1–) 2–6 cm long, slightly compressed, or irregularly moniliform, or torulose


14. Laterals rigid, complanately branched with rounded axils, ramuli (0.2–) 0.5–2 mm long

C. brownii

14. Laterals moderately rigid or lax, irregular or subdistichous but becoming loosely and irregularly branched, ramuli (2–) 5–10 (–15) mm long


15. Laterals irregularly branched, 0.5–6 (–10) cm long, primary axis 1.5–3 mm broad

C. gracilis

15. Laterals complanately branched when young, becoming displaced, slender; primary axis 2–6 (–8) mm broad


16. Axes robust, 4–6 (–8) mm broad, with secondary axes and laterals attached only to the central part of the parent axis

C. harveyi

16. Axes less robust, 2–4 mm broad, with secondary axes and laterals attached for the full width of the parent axis

C. tenuis

17. Laterals essentially complanately branched, fairly rigid with rounded axils; receptacles slightly compressed with marginal conceptacles


17. Laterals irregularly branched, rarely subdistichous, usually not rigid, with or without rounded axils; receptacles slightly compressed with marginal conceptacle ostioles, or irregularly moniliform


18. Axes distinctly broader than thick (width/thickness 2–3); laterals subdichotomous with open branching and rounded axils; vesicles absent or occasional, then elongate-ovoid and usually asymmetric; conceptacles usually bisexual

C. retorta

18. Axes thick, oblong to almost square in section (W/T 1–1.5); laterals alternate, becoming subdichotomous, axils moderately rounded; vesicles absent; plants dioecious, conceptacles unisexual

C. siliquosa

19. Receptacles slightly to distinctly compressed, margins relatively smooth and linear to undulate, sometimes torulose when dried, with two marginal rows of usually adjacent conceptacles, not markedly constricted between conceptacles


19. Receptacles with prominent, irregularly placed, swollen conceptacles, often not adjacent and with narrow sterile parts between them (more or less in 2–3 rows in C. cuspidata)


20. Receptacles usually 1.5–3 cm long, densely clustered in tufts (of laterals and short axes) along the robust primary or secondary axes; primary axes usually ridged

C. congesta

20. Receptacles 2–5 (–6) cm long, loosely and irregularly arranged on the laterals, with long and loosely branched secondary and tertiary axes; primary axes with sharp edges but not otherwise ridged

C. retroflexa

21. Epiphytic on Amphibolis; branching fairly loose with slender receptacles 2–4 (–8) cm long with distantly scattered conceptacles which are often paired; vesicles apiculate when young

C. cymodoceae

21. Epilithic; branching usually dense, receptacles with prominent swollen conceptacles grouped near the base of the receptacle and more distant above; vesicles mutic if present


22. Receptacles (0.5–) 1–3 (–5) cm long and 1–2 mm broad at conceptacles, with irregularly placed conceptacles often in two rows near the base and scattered above, with a terminal sterile awn; vesicles present on calm-water forms, 2–4 (–6) mm long and 2–3 (–4) mm in diameter

C. subfarcinata

22. Receptacles (1–) 2–6 (–8) cm long and 1.5–4 mm broad at conceptacles, with conceptacles in 2 or 3 rows in the basal half or more of the receptacle, scattered above, with a sterile awn; vesicles absent

C. cuspidata

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