Plant Identification

crupp29

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I just bought a couple of plants from my LFS and need help identifying them.
 

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#1 is likely Nymphoides hydrophylla I have a bunch in my tanks. #2 looks like a Vallisneria americana as @itiwhetu has mentioned. I am only using the width of the leaves in relation to their length and the lack of a definite twist to make the val assessment.
 
Agree on the two genera mentioned. The Vallisneria species is a complicated story; I know some members find taxonomy interesting, so the rest of this post is an excerpt from a profile of this genus that I wrote a while back for another site.

There is considerable confusion over the nomenclature of this genus [see comments below], and several different "species" and varieties may be encountered in the literature; one may therefore find the same plant under various names. The subject species V. americana is a case in point, and this will be discussed below. This species, which may often be seen under the common names of Jungle Val and Freshwater Eel Grass as well as Giant Val, is the largest; some sources give 3-4 feet for the leaf length, but others including Kasselmann (2003) give 2.3 metres (7 feet). There is a wide-leaf (blade 10-25mm wide with 5-9 veins) and a narrow-leaf (up to 10 mm with 3-5 veins) form. The name V. gigantia is synonymous with V. americana and is thus invalid as a distinct species. Some regions consider this an invasive plant; in some jurisdictions such as New Zealand it is illegal to propagate, sell or distribute this plant.

Vallisneria is distributed in all tropical and subtropical areas worldwide; in some places, such as the continental United States, they extend into the temperate zone. All species are dioecious, having male and female plants that both produce flowers. The female flowers grow on long scapes and float on the surface; male flowers are produced at the base of the male plant and become detached and float to the surface and open. The water then carries the pollen to the female flower. Seeds are not produced in aquaria, and the plants spread vegetatively by numerous daughter plants that arise from runners. These daughter plants may be left to form an extensive mat of plants or separated once they have developed several leaves and roots and planted in another location.

The confusion over the species in this genus has largely occurred due to the difficulty of identifying them by anything other than the flower structure. The leaves of plants in the same species can appear very different depending upon growing conditions, both in nature and in the aquarium.

Studying the flower of each species is complicated by the plants having distinct female and male flower forms that occur very rarely in nature and are therefore difficult to obtain. Extensive research detailed in published studies in 1982 by two independent botanists, R.M. Lowden and Christopher D.K. Cook, came to the same conclusion: the genus Vallisneria holds only two species, V. americana and V. spiralis, and both have two varieties. The relevant taxonomic criteria to determine the true species turned out to be the arrangement of the carpels in female flowers and the number of stamens in male flowers. Since the vast majority of aquarists will not be familiar with flowering Vallisneria, detailing these distinctions here would serve little purpose, but there is a summary in Kasselmann (2003) for those who are interested. The plant endemic to Australia was determined to be Vallisneria nana by Jacobs & Frank (1997).

More recent work (Les, et al., 2008) using phylogenetics has resulted in 12 species being identified by molecular data, and an additional 2 or 3 species by morphological differences within groups that were invariant at the molecular level. Two new Vallisneria species (V. australis, V. erecta) are formally described in the same study.

References:

Cook, Christopher D.K. and Ruth Luond (1982), "A Revision of the genus Nechamandra (Hydrocharitaceae)," Aquatic Botany 13, pp. 505-513.

Kasselmann, Christel (2003), Aquarium Plants, English edition, Krieger Publishing Company, Florida.

Les, Donald H., Surrey W. L. Jacobs, Nicholas P. Tippery, Lei Chen, Michael L. Moody, and Maike Wilstermann-Hildebrand (2008), "Systematics of Vallisneria (Hydrocharitaceae)," Systematic Botany, volume 33(1), pp. 49-65.

Lowden, R. M. (1982), "An approach to the taxonomy of Vallisneria L. (Hydrocharitaceae)," Aquatic Botany 13, p. 293.
 

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