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Electronic Flora of South Australia Species Fact Sheet

Caulerpa geminata Harvey 1855c:564.

Phylum Chlorophyta – Order Caulerpales – Family Caulerpaceae

Selected citations: Womersley 1966: 137.


C. sedoides (R. Brown ex Turner) C. Agardh. Harvey 1859a: pl. 72. Lucas 1936: 47. Weber van Bosse 1898: 387, pl. 34 figs 10, 11. Womersley 1956: 369.

Stolon slender to moderately robust, 0.7–2 mm in diameter, naked, usually epilithic. Erect fronds (Fig. 90C) light to medium green, with simple to several times branched axes, usually 2–8 (–15) cm high and 4–10 mm across, axes 0.7–1.5 mm in diameter, basally usually bare and above loosely covered with vesiculate ramuli on all sides or sometimes distichous or almost so, not or slightly constricted between ramuli. Ramuli (Fig. 92A) sub-spherical or ovoid to elongate-ovoid to clavate, rounded apically and basally constricted to a short pedicel on a not or slightly raised area of the axis, (1.5–) 2–4 (–7) mm long and (1–) 1.5–2 (–3) mm in diameter, thin walled.

Type from Kent I., Bass Strait (R. Brown); in BM.

Selected specimens: Port Denison, W. Aust., outer reef pools (Woelkerling, 8.xi.1968; ADU, A33140). Pearson I., S. Aust., 36 m deep (Shepherd, 10.i.1969; ADU, A34106). Rosetta Bay, Victor Harbor, S. Aust., 2 m deep (Engler, 17.iii.1980; ADU, A50951). Penguin I., Beachport, S. Aust., 1–3 m deep (Lewis, 11.vi.1973; ADU, A43589). Portarlington, Port Phillip, Vic., drift (Womersley, 9.viii.1959; ADU, A23106). Crawfish Rock, Westernport Bay, Vic., 6–9 m deep (Watson, 15.ix.1968; ADU, A32795). Walkerville, Vic., at low tide level (Sinkora A1508, 22.ii.1972; ADU, A42273). Great Taylor Bay, Bruny I., Tas., 9 m deep (Shepherd, 14.ii.1972; ADU, A42102).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: From Port Denison, W. Aust. around southern Australia and Tasmania to Bowen, Qld. (?). New Zealand. Common in rock pools near low tide level on rough-water platforms and in the upper sublittoral in calmer areas, recorded to 25 m deep.

Taxonomic notes: C. gerninata is typically a small species with entangled stolons, short erect fronds and loosely arranged ramuli. In some forms the ramuli are distichous or almost so and become more elongate; such forms give the name to the species. However, intergrades occur from ovoid ramuli on all sides of the axes to distichous, elongate ramuli. In some calm water situations where there is often current flow, the ramuli of distichous forms become unusually elongate (to 5–7 mm long). Such forms occur in Port Phillip Bay and Westernport Bay, Vic. and occasionally on rough-water coasts (e.g. Pearson I. and Beachport in S. Aust.), and need further study.


HARVEY, W.H. (1855c). Some Account of the marine botany of the colony of Western Australia. Trans. R. Ir. Acad. 22, 525–566.

HARVEY, W.H. (1859a). Phycologia Australica. Vol. 2, Plates 61–120. (Reeve: London.)

LUCAS, A.H.S. (1936). The Seaweeds of South Australia. Pt. I. Introduction and the Green and Brown Seaweeds. (Govt Printer: Adelaide.)

WEBER van BOSSE, A. (1898). Monographie des Caulerpes. Ann. Jardin Bot. Buitenzorg 15, 243–401, Plates 20–34.

WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.

WOMERSLEY, H.B.S. (1966). Port Phillip survey 1957–1963. Algae. Mem. Nat. Mus. Vict. No. 27, 133–156.

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

Illustrations in Womersley Part I, 1984: FIGS 90C, 92A.

Figure 90 image

Figure 90   enlarge

Fig. 90. A. Caulerpa flexilis (ADU, A46868). B. Caulerpa flexilis var. muelleri (ADU, A44576). C. Caulerpa geminata (ADU, A34106). D. Caulerpa annulata (ADU, Al2226).

Figure 92 image

Figure 92   enlarge

Fig. 92. A. Caulerpa geminata, ramuli on axis (ADU, A50951). B. Caulerpa annulata, ramuli on axis (ADU, A48232). C. Caulerpa cactoides, lower axis with ramuli, on stolon (ADU, A43586). D. Caulerpa racemosa var. laetevirens f. cylindracea, ramuli (ADU, A50562). E. Caulerpa papillosa, cross section of axis with ramuli (ADU, A26451). F. Caulerpa vesiculifera, cross section of axis with ramuli (ADU, A32487). G. Caulerpa simpliciuscula cross section of axis with ramuli (ADU, A32488).

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