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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae
Thallus erect, conspicuous, irregularly branched with distinct axes and laterals, heavily corticated with an inner entwined rhizoidal layer and an outer pilose layer of mostly unbranched filaments, occasional ones developing as indefinite lateral branches. Young axes with opposite whorl-branchlets, soon obscured by the cortication, whorl-branchlets alternately branched; gland cells absent. Cells uninucleate.
Reproduction: Gametophytes dioecious. Procarps borne on potentially indeterminate filaments in the pilose layer, usually on several successive cells, with the basal cell of a short lateral branch acting as the supporting cell and bearing a 4-celled carpogonial branch. Post-fertilization a prominent fusion cell develops and successive rounded gonimolobes are produced; no special involucral branchlets occur but the carposporophyte is densely surrounded by the pilose filaments. Spermatangia occur on clusters on the pilose filaments and on lateral branchlets.
Tetrasporangia occur on short lateral branches on the pilose filaments, sessile or pedicellate, subspherical, tetrahedrally divided.
Life history triphasic with isomorphic gametophytes and tetrasporophytes.
Type genus: Lasiothalia Harvey 1855a: 558.
Taxonomic notes: The structure and reproduction of Lasiothalia (with the single species, L. hirsuta) was clarified by Wollaston (1990), who suggested it was allied to the Antithamnieae. However, restriction of this tribe to genera bearing gland cells on reduced branchlets, with opposite or whorled branchlets throughout, and with not or only slightly corticate thalli, precludes inclusion of Lasiothalia in this tribe. The elaborate cortex, with outer pilose filaments among which filaments bearing reproductive structures occur, appears to warrant placing Lasiothalia in its own tribe.
References:
HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Jr. Acad. 22, 525–566.
WOLLASTON, E.M. (1990). Recognition of the genera Spongoclonium and Lasiothalia Harvey (Ceramiaceae, Rhodophyta) in southern Australia. Bot. Mar. 33, 19–30.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
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