Echinodorus uruguayensis
Arechavaleta (1903)
Family: Alismataceae. Synonyms: E. horemanii Rataj, E. subulatus Niederlein, E. martii Micheli var. uruguayensis (Arechavaleta) Hauman, E. africanus Rataj.
Etymology: Aquarium Plants 3" href="/aquarium-plants-3/echinodorus-ros.html">Echinodorus: see E. aschersoni-anus\ uruguayensis: originating from Uruguay.
Distribution: Southern Brazil, Uruguay, Chile, northern Argentina. Description: Medium-sized to large polymorph sword plant, with a long, thin rhizome, living predominantly in the water, up to 70 cm tall in the aquarium. Emersed plants: petiole 15-35 cm long, round. Blade elliptic, lanceolate, oblanceolate or narrow ovoid, 9-23 cm long, 3-8.5 cm wide, medium green. Apex acute; decurrent or acute base. Submersed plants: petiole 10-30 cm long. Leaf blade very narrow elliptic or narrow oblanceolate, strap-shaped, 30-45 cm long, 1-4 cm wide, coriaceous, light to dark olive green or black-red in color. Apex acute or obtuse aciculate; base decurrent. Margin flat or undulate; 3-5 veins, lateral veins submersed initially concurrent with the midrib. Pellucid markings (individual dots) conspicuously long and distinct (easily identifiable also in submersed blades using a magnifying glass) or absent.
Inflorescences submersed and emersed, erect, overtopping the plants or curved downwards, in most cases simple, 2-3 adventitious plants on each whorl. Peduncle up to 25 cm long, more or less thick, almost round. Inflorescence 15-25 cm long, rachis triangular, with 2-4(—6) whorls. Each whorl with 8-12 flowers. Bracts 1.2-1.7 cm long. Flowers 1.5-6.5 cm petiolate, 3 cm in diameter. Sepals 5 x 5 mm in size. Petals 1.8 cm long, 2 cm wide. 17-22 stamens; filament 1-1.5 mm; anthers 1.5 mm. Numerous carpels. Nutlets 1.8-2.3 mm long; 0.8-1.1 mm wide, aliferous, (2-3)4(5) ribs and (2)3 glands on each side, arranged fairly regularly, diagonally in one row and individually between the ribs in the nutlet's upper half; very short beak, up to 0.3 mm long.
Culture: The cultivation of this decorative solitary plant, variable in coloration and shape, requires spacious aquariums from 300 L upwards. Under optimum growth condi
- Latifoliate growth form of Echinodorus uruguayensis.
tions, several magnificent specimens will develop over several months which can display up to 100 leaves. In contrast to many large-growing sword plants, E. uruguayensis does not develop any floating or emersed leaves. The plants will prosper best in soft to medium-hard, weak acid water, in a nutrient-rich substrate (loam), under medium to intense lighting and a not too high temperature (the optimum is around 18-24 °C). Multiplication can be achieved through rhizome partition, adventitious plants and seeds. Inflorescences will form relatively rarely, usually in the short-day; certain factors, such as low temperatures and high light intensity, however, may also trigger flower formation during the long-day. In the Hoechstetter nursery, Trostberg (Germany), for example, strong plants flower in loam soil during all four seasons. Ecology: Wanke and Wanke (1994) report on several native habitats of E. uruguayensis in southern Brazil. Not only pure red and pure green but also mixed populations were found in a tributary of the Rio Peixe. Habitats in the Rio Peixe contained small-leaved or wide-bladed forms of this species. Water analyses revealed temperatures between 22.5-23 °C, pH-values between 6.6-7.11 and a conductivity of 68-82 (xS/cm. Schulze (1968), too, reports extensively about a native habitat (see ecology section on E. osiris).
Other: Several color and growth forms are being cultured, all belonging to the species of E. uruguayensis. Echinodorus horemanii, described by Rataj and characterized by missing pellucid markings in the leaf blades, belongs to this collection of E. uruguayensis formations. Color formations with dark olive green and black-red leaf blades are maintained under the synonym of E. horemanii. The last mentioned color form, occasionally mentioned as E. horemanii "red" or "black-red" in aquarium literature, is undoubtedly a hybrid, which was proven in the aquatic plant nursery Julius Hochstetter, Trostberg, through self-pollination and sowing. This hybrid often served as the base material for other crossings (for example Echinodorus 'Rubin').
Echinodorus africanus, described by Rataj in 1981, also differs only marginally from E. uruguayensis and is also to be considered as belonging to this very variable species. The author searched for the supposed habitat in Cameroon and proved (Kasselmann 1984a, 1985a) not only the nonexistence there of any Echinodorus species, but also the occurrence of only the very similar Limnophyton fluitans which belongs to the same family. Therefore the L. fluitans plants collected from this location must have been confused later during cultivation with an ecological race of E. uruguayensis. Rataj described these plants as a new species (E. africanus) in the mistaken belief that they originated from Cameroon.
Echinodorus osiris Rataj is considered by Haynes and Holm-Nielsen (1994) as a synonym of E. uruguayensis. However, as long as it has not been established that the triploid E. osiris is, in fact, a mutated form of E. uruguayensis or a hybrid, supported by several indicators, the author considers it more correct to retain the previous name of E. osiris.
Pellucid markings in E. uruguayensis,
- Narrow-leaved growth form of E. uruguayensis from Argentina.
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