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Electronic Flora of South Australia Family Fact Sheet
Phylum Phaeophyta – Order Dictyotales – Family Dictyotaceae
Thallus dichotomously or becoming laterally branched by unequal development, branches compressed to flat, with a small-celled, densely phaeoplastic cortex 1–5 cells thick and a large-celled, not or sparsely phaeoplastic medulla 1–4 (–7) cells thick. Growth from a single, transversely orientated apical cell. usually slightly protruding at the apex.
Reproduction: Reproduction with the sporophyte producing tetrahedrally divided tetrasporangia and by separate female and male plants with oogonial and antheridial sori.
Taxonomic notes: The Dictyoteae is a well defined tribe of four genera, all present in southern Australia. The differences between the genera are useful ones which are satisfactory for most species, but some plants and a few species from elsewhere [e.g. Pachydictyon aegerrime Allender & Kraft (1983, p. 116) from Lord Howe Island, which has a cortex two cells thick only at the thallus margins] "only just" qualify in their particular genus.
References:
ALLENDER, B.M. & KRAFT, G.T. (1983). The marine algae of Lord Howe Island (New South Wales): The Dictyotales and Cutleriales (Phaeophyta). Brunonia 6, 73–130.
The Marine Benthic Flora of Southern Australia Part II complete list of references.
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
KEY TO GENERA OF DICTYOTEAE
1. Surface of thallus with or without proliferations or surface ramelli; transverse section with a single cortical layer and a single medullary layer (rarely either layer is 2 cells thick near the base of occasional Glossophora plants) | 2 |
1. Surface of thallus without proliferations (except rarely, following damage, or in Dilophus marginatus); transverse section at least marginally with either more than one medullary layer, or on old parts, more than one cortical layer around the branch | 3 |
2. Thallus without surface proliferations or ramelli, except occasionally from near the base or margins; usually less than 1.5 cm broad, regularly branched | DICTYOTA |
2. Thallus surface usually densely covered with ramelli | GLOSSOPHORA |
3. Thallus | DILOPHUS |
3. Thallus with a single layer of medullary cells and a cortex | PACHYDICTYON |
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