Electronic Flora of South Australia Family Fact Sheet

ORDER POTAMOGETONALES sensu Tomlinson 1982

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.

Author: H.B.S. Womersley

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

1. Pollen grains globose to spherical, or reniform, not filiform, although sometimes adhering in chains

2

1. Pollen grains filiform

3

2. Flowers bisexual

POTAMOGETONACEAE

2. Flowers unisexual. Plants monoecious or dioecious

ZANNICHELLIACEAE

3. Flowers bisexual. Stamens 3

POSIDONIACEAE

3. Flowers unisexual. Plants monoecious or dioecious. Stamens 1, or 2 and connate

4

4. Flowers solitary or in a loose compound inflorescence

CYMODOCEACEAE

4. Male and female flowers arranged alternately on a spadix enclosed in a spathe

ZOSTERACEAE


Disclaimer Copyright Disclaimer Email Contact:
State Herbarium of South Australia
Government of South Australia Government of South Australia Department of Environment, Water and Natural Resources