Electronic Flora of South Australia Genus Fact Sheet

Genus CLADOPHORA Kützing 1843: 262, nom. cons.

Phylum Chlorophyta – Order Cladophorales – Family Cladophoraceae

Thallus of erect or prostrate filaments, occasionally loose-lying, sparsely to profusely branched often from every cell above; attached species with basal cells adherent by a discoid holdfast or by descending rhizoids arising from the basal poles of cells. Filaments usually decreasing in diameter upwards; cell division apical and/or intercalary. Cells relatively large, multinucleate; chloroplasts numerous, small and angular, many with a bilenticular pyrenoid, usually forming a parietal reticulum or closed layer.

Reproduction: Reproduction: generations isomorphic, the gametophyte producing biflagellate isogametes and the sporophyte quadriflagellate zoo(meio)spores or biflagellate zoo(mito)spores; in some species, sporophyte only present; or by thallus fragmentation.

Type species: Cl. oligoclona (Kützing) Kützing.

Taxonomic notes: A large and common genus. The European species (van den Hoek 1963) and those on Atlantic North Amercian coasts (van den Hoek 1982) have been revised and monographed, but the species from other parts of the world await detailed study.

Criteria used in separation and definition of the species of Cladophora have been discussed by van den Hoek (1963, pp. 15–19; 1982, pp. 10–19).

They include the following:

1. The organisation of the thallus, whether acropetal with cell divisions confined, or largely so, to the apical cells, or irregular with lower cell divisions resulting in irregularly scattered branches and branchlets.

2. The insertion of branches, whether apical with an inclined cross wall which may become almost horizontal with age resulting in a pseudodichotomy, or lateral with a vertical or steeply inclined cross wall which never becomes subhorizontal. Associated with this is the angle of ramification which is often variable but may be characterisitic.

3. The distinctness of main axes, the diameter of apical cells, ultimate branch cells (excluding the apical cell) and main axis cells, their length to breadth (L/B) ratios, and the relative increase in diameter from apical cells to main axes.

4. The curvature of ultimate branch systems, which vary from straight to fastigiate tufts to falcate or refract.

5.    ; The maximum number of branches per node and the density of branches.

6. The form of the apical cells, whether cylindrical or tapering and the nature of their tip, and also of lower cells, whether cylindrical, swollen or clavate.

7. The thickness of cell walls, which increases with age, and stiffness of the plant.

8. The mode of attachment, which is usually by multicellular rhizoids but may be discoid.

9.    ; The colour of the plant and density of the chloroplasts.

Macroscopic habit and height of the thallus.

11. The type of life history (usually isomorphic), the nature and form of the zooidangia, and the mode of aggregation of the zooids before release.

References:

KÜTZING, F.T. (1843). Phycologia generalis. (Leipzig.)

VAN DEN HOEK, C. (1963). Revision of the European species of Cladophora. (Brill: Leiden.)

VAN DEN HOEK, C. (1982). A taxonomic revision of the American species of Cladophora (Chlorophyceae) in the North Atlantic Ocean and their geographic distribution. Verh. k. Ned. Akad. Wet. Afd. Natuurkd. Tweede Reeks, Part 78.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

KEY TO SPECIES OF CLADOPHORA

1. Thalli occurring as entangled masses forming cushions or turfs, or vaguely tufted, without distinct basal and upper parts, or as free-floating balls of radiating filaments; branches arising mostly laterally and often slightly subterminally from the upper cell-poles, with steeply inclined cross-walls cutting them off from the axial cells

2

1. Thalli occurring as distinct, erect plants, on eulittoral rocks often as pompon-like tufts, basally attached and with distinct upper parts with irregular, or feeble to strong, acropetal growth; in lagoons and saltmarsh pools the thallus may form diffuse floating or loose-lying masses with acropetal upper parts; branches arising terminally from the upper cell-poles, cross walls between older branches and axial cells usually becoming almost horizontal but sometimes remaining oblique

5

2. Thalli occurring as indefinite hair-like entangled masses composed of long, unbranched or little branched, more or less curved, and intertwined filaments, bearing widely scattered branchlets

Section Cladophora .. 1. Cl. rhizoclonioidea

2. Thalli occurring as cushions, turfs or free-floating balls, filaments at least basally much branched

3

3. Cells near the base clavate but short; lateral branches often subterminal, opposite or serial on lower cells; cell walls thick and lamellate, giving the thallus a stiff texture; habit ball-like, free-floating at least when mature

Cl. aegagropiloidea (Section Aegagropila)

3. Cells cylindrical or nearly so; branches arising from the apical pole, sometimes opposite but never serial; cell walls thin to moderately thick; habit as entangled masses, or dense cushions or turfs or irregularly to feebly acropetally organised filaments, normally attached; filaments with many cells (especially in lower parts) producing a descending rhizoid from their basal pole

4 (Section Repentes)

4. Thallus forming dense mats or cushions to 4 cm across and high; lower filaments usually over 80 µm (70–200 um) in diameter and with many cells L/B over 5, apical cells L/B 3–16; zooids formed in normal upper cells

Cl. coelothrix

4. Thallus forming small cushions or tufts to 2 cm across and 1–2 (–5) cm high; lower filaments usually under 80 µm (50–10011m) in diameter and cells mostly L/B less than 6, apical cells L/B 2–6 (–8) and distinctly tapering; zooids formed in chains of swollen short-celled zooidangia on upper filaments

Cl. subsimplex

5. Thallus erect, basal and lower cells many times longer than apical cells and often slightly clavate; no or few intercalary divisions in lower cells

6 (Section Longiarticulatae)

5. Thallus erect, usually densely tufted, basal and lower cells not markedly longer than upper cells; intercalary divisions present in lower cells, often also in upper cells

8

6. Thallus dark green, drying dark brown-green; apical cells mostly over 100 µm (70–220 µm)in diameter, lower cells usually with annular constrictions and producing descending rhizoids also with annular constrictions

Cl. prohfera

6. Thallus light to medium green; apical cells mostly less than 100 µm in diameter, lower cells without annular constrictions and descending rhizoids

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7. Apical cells 15–35 µm in diameter, basal cell usually single

Cl. bainesii

7. Apical cells (40–) 50–1 10 (–140) µm in diameter, basal cells usually clumped

Cl. feredavi

8. Thallus with pseudo-dichotomous main axes ending in acropetal, often falcate or refracto-falcate branch systems with dominant apical growth; intercalary divisions relatively few, increasing basipetally, without frequent intercalation of branches of different ages

9 (Section Glomeratae)

8. Thallus with pseudo-dichotomous main axes but with intercalary growth very frequent to dominant and the axes bearing rows of laterals of different ages, younger (shorter) ones intercalated between older (longer) ones; acropetal organisation feeble to moderate

13 (Section Rupestres

9. Apical cells 170–300 µm in diameter, lower cells up to 350 µm in diameter

Cl. valonioides

9. Apical cells mostly less than 150 µm in diameter, lower cells less than 250 µm in diameter

10

10. Apical cells (80–) 100–120 (–160) µm in diameter, lower thallus cells (140–) 180–220 (–250) µm in maximum diameter

Cl. lehmanniana

10. Apical cells mostly less than 90 µm in diameter, lower thallus cells usually less than 200 µm in maximum diameter

11

11. Apical cells 40–70 (–80) µm in diameter; maximum number of branches per node 2 (–3); thallus usually tufted; lower filaments (100–) 135–160 (–180) µm in maximum diameter and usually 2–3 times the diameter of apical cells

Cl. laetevirens

11. Apical cells mostly under 50 µm in diameter (but varying between 15 and 75 µm); maximum number of branches per node 3–4 (–5); diameter of lower filaments usually 3–6 times that of apical cells

12

12. Diameter of the predominantly cylindrical apical cells (15–) 20–30 µm

Cl. dalmatica

12. Diameter of the more or less tapering apical cells (25–) 30–50 (–70) µm; pale plants of saltmarsh pools and lagoons narrower (apical cells approximately 25–30 µm

Cl. vagabunda

13. Apical cells usually tapering, 60–120 µm in diameter at their base, lower filaments usually over 200 µm in diameter, cells short (L/B 1–5)

Cl. hutchinsioides

13. Apical cells cylindrical or tapering, less than 65 (–80) µm in diameter, lower filaments less than 150 µm in diameter

14

14. Upper parts of main filaments unbranched over long stretches or with short or long series of tapering branchlets of differing lengths; apical cells 20–30 µm in diameter, L/B 1.5–4; main filaments 45–70 µm in diameter, L/B 1–2

Cl. montagneana

14. Upper parts of main filaments usually with densely tufted branch systems, without long series of unbranched cells though short series without branches often occur below apical cells or in lower parts

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15. Apical cells mostly cylindrical with rounded tips, 16–32 µm in diameter, L/B 2–6.5, increasing to 40–80 µm in diameter in lower main filaments (with L/B 2–3)

Cl. albida

15. Apical cells mostly more than 30 µm in diameter; lower main filaments more than 80 µm in diameter

16

16. Thallus in dense tufts or turfs, basally unbranched or little branched and peripherally more or less penicillate; apical cells cylindrical with slightly tapering tips, 50–80 µm in diameter (-90 µm in zooidangia), increasing to 80–130 µm in lower main filaments; diameter of thickest parts of main filaments 1.5–2.5 times that of apical

Cl. crinalis

16. Thallus not forming dense tufts or turfs; diameter of thickest parts of main filaments usually more than 2.5 times that of apical cells

17

17. Apical cells more or less tapering, 30–55 µm in diameter, L/B 3–10, increasing to 130–170 µm in diameter in lower main filaments; axes bearing long, often uni-lateral, rows of closely arranged, more or less appressed, branches of varying length

Cl. sericea

17. Apical cells cylindrical with rounded or slightly tapering tips, 30–50 µm in diameter, L/ B generally more than 8 (7–13), diameter increasing to 65–120 µm in the lower main filaments; axes bearing patent, more or less scattered branches in a vaguely acropetal or irregular organisation; species of calm water habitats

Cl. vadorum


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