''Zannichellia'' (common name horned pondweed) is a genus of submerged aquatic

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

, with threadlike leaves and tiny

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s. It is fully adapted to an aquatic

life cycle Life cycle, life-cycle, or lifecycle may refer to: Science and academia *Biological life cycle, the sequence of life stages that an organism undergoes from birth to reproduction ending with the production of the offspring * Life-cycle hypothesis ...

, including underwater

pollination Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, a ...

. There are perhaps five species, including '' Zannichellia palustris''. The genus is named after Gian Girolamo Zannichelli (1662–1729), Italian botanist.

Description

These slender plants grow submerged in water. The leaves are usually oppositely arranged and long and narrow. They have stipular sheaths. The flowers are unisexual. The male flowers have a single stamen with a slender filament and anthers that are 2-4- thecous. The female flowers have a cup-shaped membranous perianth. There are usually four carpels with a single pendulous ovule in each ovary. The stigma is shield shaped with toothed margins. The fruit is usually made of four long, dry achenes. The seeds are pendulous with a sub-cylindric embryo. The cotyledonous end is folded on itself twice.

Distribution

The species of this genus are widely distributed and are found growing in temperate and tropical regions around the world. They grow in brackish and salt water.

Selected species

The following species are accepted: *'' Zannichellia andina'' Holm-Niels. & R.R.Haynes *''

Zannichellia aschersoniana ''Zannichellia'' (common name horned pondweed) is a genus of submerged aquatic flowering plant, with threadlike leaves and tiny flowers. It is fully adapted to an aquatic life cycle, including underwater pollination Pollination is the tran ...

'' Graebn. *'' Zannichellia contorta'' (Desf.) Cham. *'' Zannichellia indica'' Rottler ex Royle, 1840 *'' Zannichellia obtusifolia'' Talavera, García-Mur. & H.Smit *'' Zannichellia palustris'' L. *'' Zannichellia pedicellata'' Buch.-Ham. ex Wall. *'' Zannichellia peltata'' Bertol. *'' Zannichellia tuberosa'' Lour.

References

* Potamogetonaceae Alismatales genera {{monocot-stub