Electronic Flora of South Australia Genus Fact Sheet

Genus THALASSODENDRON den Hartog 1970: 186

Phylum Magnoliophyta – Subphylum Seagrasses – Class Liliopsida – Subclass Alismatidae – Order Potamogetonales – Family Cymodoceaceae

Dioecious; perennials with robust, sympodially branched rhizomes bearing 1 or 2 erect unbranched (or little branched) stems at every fourth internode (Tomlinson 1974, p. 119). Stems with a tuft of leaves at the summit and scars of fallen leaves below. Roots 1–5 arising together, only at the internode preceding the stem-bearing internode. Leaf sheath compressed, ligulate, auriculate, amplexicaul; blade flat, linear with denticulate margins, primary veins numerous, parallel, connected by oblique crossveins; apex coarsely denticulate; blade and sheath shed together leaving an annular scar. Squamules present in each leaf axil. Tannin cells numerous. Flowers solitary and terminal on short lateral shoots, each flower enclosed by 4 leafy bracts. Male flower with 2 anthers, each with a terminal appendage. Female flower consisting of 2 free carpels each with a short style and 2 stigmas. Fruit a 1-seeded nut; seed viviparous, remaining attached to the parent plant after germination. Seedling free-floating for a time.

Type species: Thalassodendron ciliatum (Forskal) den Hartog.

Taxonomic notes: Two species, one endemic to south Western Australia.

References:

DEN HARTOG, C. (1970). The seagrasses of the World. Verh. k. ned. Akad. Wet. Afd. Natuurk., ser. 2, 59(1), 1–275 (-1–31 Plates).

TOMLINSON, P.B. (1974). Vegetative morphology and meristem dependence-the foundation of productivity in seagrasses. Aquaculture 4, 107–130.

The Marine Benthic Flora of Southern Australia Part I complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
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