Family Zosteraceae
Description: Monoecious, submerged marine or estuarine rhizomatous perennials; rhizomes extensive, with fibrous roots at the nodes.
Leaves with blade linear, 3- or >3-veined, apex entire or notched; sheath auriculate and ligulate.
Inflorescence terminal, a racemose arrangement of spatheate spadices, each resembling vegetative leaves. Flowers unisexual. Spadix linear, bisexual, with about 6 flowers of each sex; retinaculae (bract-like appendages on spadix) linear to obliquely ovate or broad-triangular. Male flowers of 2 longitudinally dehiscent 1-locular anthers; pollen filiform. Female flowers of 1 laterally attached carpel; ovule 1, pendulous; style short; stigma 2-fid.
Fruit an achene; seed striate. Whole inflorescence dispersed as a unit.
Distribution and occurrence: World: 2 or 3 or more genera (depending on generic delimitation), c. 20 species, cosmopolitan. Australia: 2 genera, 4 species (native), N.S.W., Vic., Tas. S.A., W.A.
External links:
Angiosperm Phylogeny Website (Family: Zosteraceae, Order: Alismatales)
Wikipedia
Text by S. W. L. Jacobs 91993); edited KL Wilson (Feb 2013)
Taxon concept:
| | Key to the genera | |
| 1 | Both flowering and vegetative erect stems with elongated internodes present; retinacula linear-lanceolate; rhizome and stem internodes with 4 or more cortical bundles near the middle | Heterozostera |
| Only flowering erect stems with elongated internodes present; retinacula obliquely ovate or triangular; rhizome and stem internodes with 2 cortical bundles near the middle | Zostera |
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