Electronic Flora of South Australia Family Fact Sheet

SUBCLASS ALISMATIDAE Takhtajan

Phylum Magnoliophyta – Subphylum Seagrasses – Class Liliopsida

Plants herbaceous, more or less aquatic. Vascular system generally not strongly lignified, often much reduced; vessels confined to the roots or wanting. Leaves simple. Perianth frequently much reduced or absent; gynoecium mostly apocarpous, sometimes monocarpous (except in Hydrocharitales where carpels are weakly united to form a compound ovary); endosperm absent in most taxa; pollen trinucleate.

Taxonomic notes: Two of the five orders are represented by seagrasses in southern Australia.

References: The Marine Benthic Flora of Southern Australia Part I

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 ORDERS OF SEAGRASSES

1. Leaves differentiated into a petiole and blade. Flowers bracteate. Perianth in 1 or 2 whorls, each of 3 free segments. Carpels (2–) 3–15, weakly joined to form a compound, inferior ovary

HYDROCHARITALES

1. Leaves linear to terete with a sheathing base, not differentiated into a petiole and a blade. Flowers usually ebracteate (bracts if present small and inconspicuous). Perianth when present generally much modified, never with distinct sepals and petals. Carpels 1-several, free, ovary superior

POTAMOGETONALES


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