Alismataceae Common Name: Origin:
This is a cultivar from the wild species that occurs in Peru and Bolivia in South America. Ideal position in aquarium
Excellent foreground to midground plant individually or in groups. Lighting requirements
Moderate to bright. Growth rate
Slow Minimum Tank Suggestion
Any Water parameters
Soft to moderately hard, acidic to basic (pH up to 8.0) water, temperature 21-28C/70-82F. Description
A striking contrast plant to the other species in the genus. The oval dark green leaves are sturdy and "hammered" in appearance, giving them a crinkly look. A thick rosette of leaves arise from the rhizome; the plant grows according to the light intensity, reaching a maximum height from 2 to 6 inches, about half the height of the original wild species.
Propagation is by plantlets arising from the flower stalks. Growth is moderately slow even under ideal conditions.
The natural (wild) species was described by Rataj (1970); the species epithet means small-flowered. This cultivar 'Tropica' was cultivated in Singapore and Sri Lanka and in the early 1980's the Danish aquatic plant nursery Tropica received a shipment; the Danish botanists Jacobsen & Holm-Nielsen described the cultivar in 1985 and named it in honour of the Tropica nurseries. The cultivar is shown in the first photo, the wild species in the second.
Some of the most beautiful and useful plants for the tropical aquarium are found among the Echinodorus
, a genus distributed in the tropical and sub-tropical regions of the Americas from the lower United States down to Argentina; the two "African" species of Rataj are almost certainly erroneous (Kasselmann, 2003). The genus name derives from the Greek echinos
[hedgehog] and doros
[pipe or hose] referring to the spiny fruit. The English common name "sword plant" comes from the general lanceolate shape of the leaf of most species and is generally used for all plants in this genus although other non-Echinodorus
plants may sometimes appear under the name "sword."
Larger-sized species have a rhizome, whereas smaller species are stoloniferous. All species are perennial or annual aquatic or marsh plants found in boggy flood areas or along the banks of stagnant or slow-flowing waters. Except for the very few species that are permanently submersed, Echinodorus
plants spend half the year emersed (when they flower) and the remainder submersed during the flood season. Leaves arise in a rosette and can be very variable not only between emersed and submersed forms but also when cultivated under different conditions. Correct identification often requires study of the flower. Inflorescences (flower stalks) are formed in all species; when grown permanently submersed in the aquarium most species will not flower but plantlets (daughter plants) will develop from the nodes on the inflorescence.
Confusion exists over the number of species, and many have been known under different names. In his earlier revision of the genus, Rataj (1975) listed 47 species. A major revision by the botanists R.R. Haynes and L.B. Holm-Nielsen (1994) lists 26 species. In 2004, Rataj increased the number of species to 62. More recent work by Samuli Lehtonen--incorporating cladistic analysis using morphological data--has proposed 28 valid species (Lehtonen, 2007).
Haynes & Holms-Nielsen (1994) considered the natural species, E. parviflorus
, along with E. amazonicus
and E. bleherae
to be synonyms of E. grisebachii
. Kasselmann (2002) suggests that the different habitus of the submersed plants between these "species" is reason to retain the present names in the hobby. But since Lehtonen's extensive analysis (2007) supports the findings of Haynes & Holms-Nielsen, we should be prepared for significant re-naming within this genus. As the name is so well known, we are retaining it for the present to avoid confusion. References:
Haynes, R.R. and L.B. Holm-Nielsen (1994), "The Alismataceae," Flora Neotropica
, Vol. 64, pp. 1-112.
Kasselmann, Christel (2002), Aquarium Plants
[translated by Ulf Kotlenga].
Lehtonen, Samuli (2006), "Phylogenetics of Echinodorus (Alismataceae) based on morphological data," Botanical Journal of the Linnean Society
, 150, pp. 291-305.
Lehtonen, Samuli (2007), "An integrative approach to species delimitation in Echinodorus (Alismataceae) and the description of two new species," Kew Bulletin
Vol. 63, No. 4, pp. 525-563.
Lehtonen, Samuli and Leena Myllys (2008), "Cladistic analysis of Echinodorus (Alismataceae): simultaneous analysis of molecular and morphological data," Cladistics, Vol. 24, No. 2 (April 2008), pp. 218-239.
Rataj, Karel (2004), "A New Revision of the Swordplant Genus Echinodorus Richard 1848 (Alismataceae)," Aqua--Journal of Ichthyology and Aquatic Biology
, Special Publication No. 1, March 2004. Contributing Members
The following members have contributed to this profile: Byron