Electronic Flora of South Australia Family Fact Sheet
Phylum Magnoliophyta – Subphylum Seagrasses – Class Liliopsida – Subclass Alismatidae – Order Potamogetonales
Monoecious or dioecious; annual or frequently ephemeral, rarely perennial, slender, submerged, rhizomatous, aquatic herbs. Rhizomes creeping, usually sympodially branched, rooting at the nodes and giving rise to erect, much-branched, leafy and flower-bearing shoots. Roots unbranched, I-several per node. Leaves alternate, more or less distichous, sheathing at the base; sheath open, margins overlapping, ligulate, auriculate; blade linear. Squamules usually a pair at each node. Tannin cells rare or absent. Flowers usually terminal. Male flower perianth present or absent; one stamen with 1–6 pollen sacs (each containing a pair of microsporangia); pollen grains globose. Female flower perianth of 3 free tepals or a membranous cupule; carpels 1–8, free, short-stalked; ovule 1, anatropous and pendulous. Fruit an achene.
Taxonomic notes: A family of four genera mostly in fresh or brackish water, widely distributed in temperate and tropical regions. One genus, Lepilaena, has marine representatives in southern Australia.
Zannichelliaceae is a distinct family with no close relatives and no obvious ancestors (Tomlinson 1982, p. 34). Generic limits within the family, and some aspects of morphological development are discussed by Tomlinson & Posluszny (1976) and Posluszny & Tomlinson (1977).
POSLUSZNY, U. & TOMLINSON, P.B. (1977). Morphology and development of floral shoots and organs in certain Zannichelliaceae. Bot. J. Linn. Soc. 75, 21–46.
TOMLINSON, P.B. & POSLUSZNY, U. (1976). Generic limits in the Zannichelliaceae (sensu Dumortier). Taxon 25, 273–279.
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.
Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
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State Herbarium of South Australia