Electronic Flora of South Australia Genus Fact Sheet
Phylum Phaeophyta – Order Chordariales – Family Spermatochnaceae
Thallus irregularly subdichotomous to alternately branched, haplostichous, slender, 5–50 cm long, 0.5–1 (–2) mm in diameter below, tapering gently above. Branch apices with a single filament with apical growth. Medulla consisting of the axial filament and whorls of 4–5 lateral cells from each axial cell, becoming separated to give a partly hollow medulla. Cortex 2–4 cells thick, pseudoparenchymatous, developed laterally and radially from the whorls of medullary cells, smooth surfaced between the assimilatory tufts. Primary assimilatory filaments formed close to branch apices but usually not obscuring the apical cell, separating below as the cortical cells enlarge, with secondary assimilatory filaments developing from adjacent cortical cells to form tufts of filaments each 4–10 cells long, with associated phaeophycean hairs and sporangia.
Reproduction: Reproduction by unilocular sporangia producing meiospores which develop into filamentous gametophytic microthalli bearing plurilocular gametangia with isogametes, which fuse to form the sporophytic macrothallus or may germinate without fusion forming haploid microthalli (Killer 1981). Rarely the macrothallus bears uniseriate plurilocular sporangia (Sauvageau 1936, fig. 1F,G).
Life history diplohaplontic and heteromorphic.
Type species: S. paradoxus (Roth) Kützing, type cons.
Taxonomic notes: A genus of a single species, characterised by the single axial filament and smooth cortex (c.f. Stilopsis) between the assimilatory tufts.
KÜTZING, F.T. (1843). Phycologia generalis. (Leipzig.)
SAUVAGEAU, C. (1936). Second mémoire sur les algues Phéosporées de Villefranche-sur-Mer. Bull. Stn biol. Arcachon 33, 117–204.
The Marine Benthic Flora of Southern Australia Part II complete list of references.
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
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State Herbarium of South Australia