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Electronic Flora of South Australia Family Fact Sheet
Phylum Magnoliophyta – Subphylum Seagrasses – Class Liliopsida – Subclass Alismatidae
Perennial (or rarely annual) herbs, aquatic or semi-aquatic, rooted to the substrate. Leaves basal or cauline, commonly sheathing at the base, mostly ligulate (ligule absent in Potamogetonaceae); venation parallel, sheathing base generally subtending squamules at the node. Flowers unisexual or bisexual, mostly small and inconspicuous, usually ebracteate (or bract small and inconspicuous). Perianth absent or when present generally much modified. Pollination anemophilous or hydrophilous. Carpels 1-several, free, uni-ovulate; ovary superior. Fruit usually achenous.
Taxonomic notes: Six families widely distributed around the world; 5 of these contain marine species in southern Australia.
References:
TOMLINSON, P.B. (1982). Helobiae (Alismatidae) including the seagrasses. Vol. VII. Anatomy of the Monocotyledons (ed. C.R. Metcalfe). (Clarendon Press: Oxford.)
The Marine Benthic Flora of Southern Australia Part I complete list of references.
Publication:
Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
KEY TO FAMILIES OF POTAMOGETONALES
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1. Pollen grains globose to spherical, or reniform, not filiform, although sometimes adhering in chains | 2 |
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1. Pollen grains filiform | 3 |
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2. Flowers bisexual | POTAMOGETONACEAE |
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2. Flowers unisexual. Plants monoecious or dioecious | ZANNICHELLIACEAE |
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3. Flowers bisexual. Stamens 3 | POSIDONIACEAE |
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3. Flowers unisexual. Plants monoecious or dioecious. Stamens 1, or 2 and connate | 4 |
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4. Flowers solitary or in a loose compound inflorescence | CYMODOCEACEAE |
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4. Male and female flowers arranged alternately on a spadix enclosed in a spathe | ZOSTERACEAE |
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Email Contact: State Herbarium of South Australia |
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