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Order Bryopsidales

Family Codiaceae

Genus Codium Stackhouse

Thallus coenocytic, filamentous, filaments adhering to form variously-shaped spongy structures; holdfast a tuft of rhizoids. Anatomically comprising a medulla of usually colourless filaments and an outer layer of usually terminally-swollen filaments (utricles) containing chloroplasts. Cell-wall thickenings usually present at junction of utricles and internal filaments. Species delimited on external habit and size and shape of utricles, which may bear hairs or scars. Note that utricles from near the tips of thalli are smaller, and dimensions given here are based on samples from near the middle of thalli.

Gametangia arise laterally from utricles; after meiosis the contents divide into biflagellate gametes which are extruded through ruptures apices of gametangia. Male gametes smaller, with only one or two chloroplasts, female gametes larger with numerous chloroplasts. Species may be monoecious or dioecious.

The descriptions below are largely based on the monograph on South African Codium by Silva (1959), which remains the authoritative work on this genus in the region.


Key to Codiums of south coast

1 a Thallus prostrate


1 b Thallus erect


2 a Utricles clearly visible to naked eye| 1.5-2.5 mm in diameter| thallus globose and light green

C. megalophysum

2 b Utricles not clearly visible to naked eye and less than 1 mm diameter| thallus smooth or velvety| various shapes


3 a Thallus circular in outline| more than 10 mm thick| globose; utricles longer than 1.5 mm| 350-520 µm diameter at apex

C. papenfussii

3 b Thallus with irregular outline


4 a Thallus dichotomously branched| mainly or entirely prostrate

C. prostratum

4 b Thallus not dichotomously branched


5 a Thallus strikingly membrane-like| 1.5–3 mm thick| loosely attached to substratum

C. pelliculare

5 b Thallus in mature parts usually thicker than 3 mm| applanate


6 a Thallus with well-developed more-or-less free lobes| utricles markedly ninepin-shaped

C. stephensiae

6 b Thallus attached on most of under-surface| utricles cylindrical or club-shaped


7 a Utricles mostly shorter than 1 mm| only edges of thallus free

C. lucasii subsp. capense

7 b Utricles mostly longer than 1 mm| thallus firmly attached to substratum over whole under surface


8 a Utricles without hairs| gametangia cylindrical to spindle-shaped

C. incognitum

8 b Utricles with abundant hairs| gametangia lanceolate-ovoid or flask-shaped

C. spongiosum

9 a Thallus flattened| up to several cm wide

C. platylobium

9 b Thallus completely cylindrical or largely cylindrical except sometimes for flattening at forkings


10 a Utricles markedly mucronate (pointed tips)

C. fragile subsp capense

10 b Utricles non-mucronate


11 a Branch forks of noticeably unequal length| giving thallu cervicorn appearance| branches uneven in width

C. pocockiae

11 b Branch forks of similar length| branches of even width but may narrow towards tips


12 a Thallus pale green| translucent at tips| markedly flattened at forkings

C. tenue

12 b Thallus dark green| not translucent at tips| terete or slightly compressed throughout


13a Utricles often longer than 1 mm

C. duthieae

13 b Utricles seldom as long as 1 mm


14 a Utricles capitate (milk-bottle shaped)| slender| with tiny pits

C. capitatum

14 b Utricles stout| cylindrical to club-shaped


15 a Utricles without hairs| thallus terete throughout| 3-6 mm diameter| not narrowing towards tips

C. isaacii

15 b Hairs or hair-scars common on utricles| thallus terete except for flattening near base| narrowing from 4-8 mm lower down to 1.5 - 2 mm near apices

C. extricatum



Silva, P.C. (1959). The genus Codium (Chlorophyta) in South Africa. Journal of South African Botany 25: 101-165, 22 figs, Plates II-XVI.


Cite this record as:

Anderson RJ, Stegenga H, Bolton JJ. 2016. Seaweeds of the South African South Coast.
World Wide Web electronic publication, University of Cape Town,; Accessed on 26 February 2024.