| Aponogeton | |
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| A. distachyos, foliage and inflorescence at water surface | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Order: | Alismatales |
| Family: | Aponogetonaceae Planch.[1] |
| Genus: | Aponogeton L.f. |
| Species | |
See text | |
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TheAponogetonaceae (theCape-pondweed family oraponogeton family) are a family offlowering plants in the orderAlismatales.
In recent decades the family has had universal recognition by taxonomists.[2] TheAPG system (1998) andAPG II system (2003) treat it in the order Alismatales in the clademonocots. The family consists of only one genus,Aponogeton, with 56 known species (Christenhusz & Byng 2016[3]) ofaquatic plants, most of which have been included in a molecular phylogeny by Chen et al. (2015). The name was published inSupplementum Plantarum 32: 214 (1782) and is derived from a geographic location neighboring (geton) the Apono tribal district of coastalGabon.[4] Some species are used asornamental plants in aquariums.
They areaquatic plants, which are found in tropical to warm temperate regions ofAfrica,Asia andAustralasia.[5]
Aponogeton distachyos is originally fromSouth Africa but has become naturalised in SouthAustralia, WesternSouth America, and WesternEurope.
Individual plants are not always easy to identify due to hybridization (particularly those sold asA. crispus - which are often cultivated hybrids withA. natans orA. 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 andA. ulvaceus. Additionally,Aponogeton bernierianus,A. capuronii,A. decaryi andA. 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 andA. undulatus are useful aquarium plants.Aponogeton jacobensii,A. natans andA. loriae, too, were cultivated several times but have not proven themselves under aquarium conditions.
The oldest known fossils of the genus are pollen from the Late Cretaceous (Campanian) of Wyoming in North America, approximately 82-84 million years old. Other fossilAponogeton pollen is known from Canada and Greenland, dating to theEocene, approximately 46 and 44-40 million years old respectively, indicating that the genus likely originated in the Northern Hemisphere.[6]
Manyspecies grow in temporarily still or flowing waters and live through the dry period as a dormanttuber. They are fully aquaticherbaceous plants with milky sap, becomingdormant 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 thedry season by shedding their leaves and undergoing a dormant period.
Almost allAponogeton 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 storagerhizome ortuber During the resting period, the tuber survives in the soil in order to again sprout during the following vegetation period. Tubers inAponogeton species have a high resistance to drying out. This ability to store water is exploited, for instance, in the annual export of thousands of dormantA. crispus specimens, shipped in large bags in a totally dry state.
The tubers of several species are eaten by humans and their livestock. Some are grown as ornamental plants inaquariums orponds. 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".[7]
AllAponogeton species are easy to grow when their preferences are met. The Madagascar lace plants (A. madagascarensis) require special handling as they prefer cooler water – 70 °F (21 °C) as a maximum[citation needed]. As of 2010, the Australian species exist in very small numbers in the hobby trade.
The African species in particular, (with the exception ofA. rigidifolius, which has arhizome 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 50–64 °F (10–18 °C), until smallleaves are seen to sprout from the tuber, when they can be returned to the pond or aquarium.[8]
Authority control databases: National |
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