Electronic Flora of South Australia Family Fact Sheet

TRIBE DICTYOTEAE Greville

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.

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

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 1–3 mm long; thallus usually 1–5 cm broad, sparingly subdichotomously branched

GLOSSOPHORA

3. Thallus 2–4 medullary cells thick at least marginally, cortex single layered

DILOPHUS

3. Thallus with a single layer of medullary cells and a cortex 2–5 cells thick around on older, lower branches

PACHYDICTYON


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