The Aponogetonaceae (the Cape-pondweed family or aponogeton family) are a family of

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 language, Greek words ('container, vessel') and ('seed'), and refers to ...

s in the order

Alismatales The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Description The Alismatales compris ...

. In recent decades the family has had universal recognition by taxonomists. The

APG system The APG system (Angiosperm Phylogeny Group system) of plant classification is the first version of a modern, mostly molecular-based, system of plant taxonomy. Published in 1998 by the Angiosperm Phylogeny Group, it was replaced by the improved APG ...

(1998) and

APG II system The APG II system (Angiosperm Phylogeny Group II system) of plant classification is the second, now obsolete, version of a modern, mostly molecular-based, system of plant taxonomy that was published in April 2003 by the Angiosperm Phylogeny Gr ...

(2003) treat it in the order Alismatales in the clade

monocots Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of t ...

. The family consists of only one genus, ''Aponogeton'', with 56 known species (Christenhusz & Byng 2016 ) of

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments ( saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s, most of which have been included in a molecular phylogeny by Chen et al. (2015). The name was published in '' Supplementum Plantarum'' 32: 214 (1782) and is derived from a geographic location neighboring (''geton'') the Apono tribal district of coastal

Gabon Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the north, ...

. Some species are used as

ornamental plant Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...

s in aquariums.

Distribution

They are

s, which are found in tropical to warm temperate regions of

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

and

Australasia Australasia is a region that comprises Australia, New Zealand and some neighbouring islands in the Pacific Ocean. The term is used in a number of different contexts, including geopolitically, physiogeographically, philologically, and ecologi ...

.Watson, L. & Dallwitz, M. J. (1992 onwards)
Aponogetonaceae
''Aponogeton distachyos'' is originally from

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring coun ...

but has become naturalised in South

Australia Australia, officially the Commonwealth of Australia, is a sovereign country comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands. With an area of , Australia is the largest country b ...

, Western

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the sout ...

, and Western

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

. Individual plants are not always easy to identify due to hybridization (particularly those sold as ''A. crispus'' - which are often cultivated hybrids with ''A. natans'' or ''A. rigidifolius''). Generally an Aponogeton from Asia will have a single bloom stalk, while those from African heritage (including Madagascar) will have multiple blooming stems on the same flower stalk. Even though seventeen species are found in Africa, only one of them, ''A. distachyos'', has been continuously maintained as a plant in garden ponds. Several of the eleven Madagascan species have been introduced as new aquarium plants in the early 21st century. At present, the following plants from Madagascar are in culture: '' Aponogeton boivinianus'', '' A. longiplumulosus'', '' A. madagascariensis'' and '' A. ulvaceus''. Additionally, '' Aponogeton bernierianus'', '' A. capuronii'', '' A. decaryi'' and '' A. tenuispicatus'' have been imported on several occasions but have not achieved any wider distribution because they are difficult to maintain. From the sixteen representatives of this genus from Asia and Australia,'' A. crispus'', '' A. elongatus'', '' A. rigidifolius'', '' A. robinsonii'' and '' A. undulatus'' are useful aquarium plants. '' Aponogeton jacobensii'', '' A. natans'' and '' A. loriae'', too, were cultivated several times but have not proven themselves under aquarium conditions.

Evolution

The oldest known fossils of the genus are pollen from the Late Cretaceous (

Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campani ...

) of Wyoming in North America, approximately 82-84 million years old. Other fossil ''Aponogeton'' pollen is known from Canada and Greenland, dating to the

Eocene The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', "da ...

, approximately 46 and 44-40 million years old respectively, indicating that the genus likely originated in the Northern Hemisphere.

Ecology

left, ''A. distachyos'', habit, showing aerial and submerged parts Many

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate ...

grow in temporarily still or flowing waters and live through the dry period as a dormant

tuber Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growi ...

. They are fully aquatic

herbaceous Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials. Definitions of "herb" and "herbaceous" The fourth edition of ...

plants with milky sap, becoming dormant during drought conditions. Most species grow from tubers. Most Asian species remain submerged all year round, while the starchy tubercles of the African species are able to survive the

dry season The dry season is a yearly period of low rainfall, especially in the tropics. The weather in the tropics is dominated by the tropical rain belt, which moves from the northern to the southern tropics and back over the course of the year. The ...

by shedding their leaves and undergoing a dormant period. Almost all ''Aponogeton'' species go through resting and growth phases in their natural locations, triggered by the local ecological conditions. During growth periods, the plant will deposit proteins, fats, carbohydrates and mineral substances in the storage

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow h ...

During the resting period, the tuber survives in the soil in order to again sprout during the following vegetation period. Tubers in ''Aponogeton'' species have a high resistance to drying out. This ability to store water is exploited, for instance, in the annual export of thousands of dormant ''A. crispus'' specimens, shipped in large bags in a totally dry state.

Economic uses

The tubers of several species are eaten by humans and their livestock. Some are grown as ornamental plants in

aquarium An aquarium (plural: ''aquariums'' or ''aquaria'') is a vivarium of any size having at least one transparent side in which aquatic plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, ...

s or

pond A pond is an area filled with water, either natural or Artificiality, artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% Aquatic plant, emergent vegetation helps in disting ...

s. The 1889 book 'The Useful Native Plants of Australia' records that "The tuberous roots of these water-plants are starchy, and of excellent taste, though not large".

Cultivation

All ''Aponogeton'' species are easy to grow when their preferences are met. The Madagascar lace plants (''A. madagascarensis'') require special handling as they prefer cooler water – as a maximum. As of 2010, the Australian species exist in very small numbers in the hobby trade.

Rest periods

The African species in particular, (with the exception of ''A. rigidifolius'', which has a

and not a tuber, experience a natural rest period, corresponding to their habitat drying out in the wild. The Asian species may also have a rest period, but this is related only to temperature. As the plant stops growing, it can be taken out of the pond or aquarium and put in a bowl of damp sand. Keep the bowl in a dark, cool place, with the sand kept damp, for approximately 2–3 months at a temperature of about , until small

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ...

are seen to sprout from the tuber, when they can be returned to the pond or aquarium.Gesting, B. ''Nature and Aquarium''

Selected species

*'' Aponogeton abyssinicus'' Hochst. ex A. Rich. *'' Aponogeton afroviolaceus'' Lye *'' Aponogeton angustifolius'' Ait. *'' Aponogeton azureus'' H. Bruggen *'' Aponogeton bernierianus'' (Decne.) Hook. *'' Aponogeton boivinianus'' Baill. ex Jum. *'' Aponogeton bogneri'' H. Bruggen *'' Aponogeton bullosus'' H.Bruggen *'' Aponogeton capuronii'' H. Bruggen *'' Aponogeton crispus'' Thunb. *'' Aponogeton desertorum'' Zeyh. ex A. Spreng. *'' Aponogeton distachyos'' L.f. *'' Aponogeton elongatus'' F.Muell. ex Benth. *'' Aponogeton euryspermus'' Hellq. & S.W.L.Jacobs *'' Aponogeton fotianus'' J. Raynal *'' Aponogeton junceus'' Lehm. *'' Aponogeton lakhonensis'' A. Camus (1909) *'' Aponogeton longiplumulosus'' H. Bruggen (1968) *'' Aponogeton madagascariensis'' (Mirb.) H. Bruggen *'' Aponogeton natalensis'' Oliv. *'' Aponogeton natans'' (L.) Engl. & K. Krause *'' Aponogeton nudiflorus'' Peter. *''

Aponogeton ranunculiflorus ''Aponogeton ranunculiflorus'', the Sehlabathebe water lily, is a tiny and endangered species of aquatic plant, that belongs to the pondweed family Aponogetonaceae. It is protected in the Sehlabathebe National Park in the mountains of Lesotho, w ...

'' Jacot Guill. & Marais *'' Aponogeton rehmannii'' Oliv. *'' Aponogeton rigidifolius'' H. Bruggen *'' Aponogeton stuhlmannii'' Engl. *'' Aponogeton subconjugatus'' Schumach. & Thonn. *'' Aponogeton troupinii'' J. Raynal *'' Aponogeton ulvaceus'' Bak. *'' Aponogeton undulatus'' Roxb. *'' Aponogeton vallisnerioides'' Baker *'' Aponogeton satarensis'' Sources:African Flowering Plants Database
''Aponogeton''
/ref>Huxley, A., ed. (1992). ''New RHS Dictionary of Gardening''. Macmillan .Govaerts, R. et al. (2019
Plants of the world online: ''Aponogeton''.
Board of Trustees of the Royal Botanic Gardens, Kew. Retrieved 20 March 2019.

References

External links

in L. Watson and M.J. Dallwitz (1992 onwards).
The families of flowering plants
descriptions, illustrations, identification, information retrieval.'' Version: 9 March 2006. https://web.archive.org/web/20070103200438/http://delta-intkey.com/
''Monocot families'' (USDA)

Aponogetonaceae in the ''Flora of North America''

NCBI Taxonomy Browser

links at CSDL, Texas

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{{Authority control Alismatales genera Aquatic plants Freshwater plants Taxa named by Carl Linnaeus the Younger