Tropical Fish Keeping - Aquarium fish care and resources

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-   -   Echinodorus bleherae (http://www.tropicalfishkeeping.com/substrate-rooted-plants/echinodorus-bleherae-180362/)

TFK Team 05-16-2013 01:59 PM

Echinodorus bleherae
 
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Family: Alismataceae

Common Name: Amazon Sword

Origin and Habitat: Tropical regions of South America

Ideal position in aquarium

In smaller aquaria, use as a specimen plant. In larger aquaria, 4-feet and more in length, can be used as specimen or background plants.

Lighting requirements

Moderate; grows well in diffused light. May manage in lower light.

Growth rate

Medium

Minimum Tank Suggestion

See description

Water parameters for Amazon Sword

Soft to slightly hard (hardness to 15 dGH), acidic to slightly basic (pH 5 to 7.5) water, temperature 24-28C/75-82F.

Description

One of the most common aquarium species of sword plants and one of the most hardy and beautiful. Mid-green leaves numbering anywhere up to 30 arise from the crown and grow out in a fan formation to a length of up to 50 cm (20 inches) with the blade lanceolate and acute at both ends. Will often grow to the surface, so in larger tanks the plant will generally develop much larger in height if provided with adequate fertilization. A deep substrate is needed (minimum 3-4 inches); the root system is large, and will spread vertically and horizontally through the substrate far from the plant.

Echinodorus plants are heavy feeders, and require regular fertilization with a comprehensive liquid fertilizer and/or substrate fertilizer. If the leaves develop yellowing or transparent patches, it is a sign of insufficient nutrients, sometimes but not always iron, as several nutrient deficiencies will cause these conditions. A balanced comprehensive fertilizer is much more preferable to iron fertilization.

E. bleherae will produce an inflorescence (flower stalk), sometimes two or three at the same time and up to six or seven each year, which grow to the surface but underwater develop plantlets from the nodes. It does not send out substrate runners. The plantlets may be detached as new young plants once they develop sufficient roots and leaves, usually within 2-3 months.

As with the majority of species in this genus, E. bleherae is a bog (marsh) plant in nature, spending half the year emersed (during which it flowers) and half submersed. It prefers to grow submersed and therefore adapts well to fully-submersed conditions and is thus an excellent aquarium plant. Aquatic leaves will be quite different from emersed leaves, in shape, size and texture. Newly-purchased plants have often been propagated emersed by nurseries and when grown in the aquarium the developing submersed leaves will be different from those on the plant at purchase, and the older leaves will yellow and should then be removed.

This species is very similar in appearance and growth to Echinodorus amazonicus [see discussion below], but the latter has narrower and shorter leaves (maximum 16-20 inches, frequently much less) and does not fare as well in basic/alkaline harder water.

This species was originally described (Rataj, 1970) as Echinodorus bleheri and the name was corrected by Dr. Rataj to E. bleherae although the original incorrect gender is still encountered. The species was named in honour of Amanda Bleher who first exported it from Brazil over 40 years ago. As noted below, this name may be botanically incorrect.

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). Echinodorus derives from the Greek echinos [hedgehog] and doros [pipe or hose] referring to the spiny fruit. The English common name of "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 & Holm-Nielsen (1994) considered this species, E. bleherae, along with E. amazonicus and E. parviflorus to be conspecific [the same species] as E. grisebachii. Kasselmann (2002) suggests that the different habitus of the submersed plants between these three "species" is reason to retain the present names in the hobby. But since Lehtonen's extensive analysis (2007) supports the findings of Haynes & Holm-Nielsen, we should be prepared for significant re-naming within this genus. As the current species 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 [English language edition, 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.

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