In the last HAPpenings I mentioned I had done some research on Vallisneria, and I closed by saying that things were getting interesting. Well, read on to see what I found out. First, though, I would like to thank Anne Savannah for getting this whole thing started and lending me her plant bible. Thanks also to Bill Maher, our newest HAP participant, for calling me on the Thanksgiving Weekend and showing me a female Vallisneria americana in bloom. Luckily for the Blooming Competition contestants, Bill did not enter in the competition, so the race is still on. Congratulations Bill, Vallisneria blooms are not common in aquaria around here.
So what is a Vallisneria? According to Hortus Third it is a genus belonging to the family Hydrocharitaceae*. It contains eight to ten species of submersed, dioecious (having separate sexes), grasslike aquatic herbs native to tropical and temperate regions. The leaves are ribbon like. The male flowers are contained “in a head subtended by an ovoid 3-valved spathe on a short scape”. This head looks like the tip of a new runner but larger, transparent, and filled with white dots (see page 53 of the Baensch Aquarium Atlas, Volume 2). The female flowers are “solitary and sessile in a tubular spathe on a long scape coiled or spiraling in fruit”. Imagine a zucchini only a couple of millimeters wide and 20 mm long, with a small flower with triangular petals at one end and a spring at the other end attaching it to the plant. See pictures in the Tropica catalogues (either the official one or the T.F.H. books). The coiled scape is what actually gave Vallisneria spiralis its name, not the twisted leaves as one might think.
The female flowers reach the surface while attached to the plant. The male flowers, on the other hand, detach from the plant when they are ripe and then float to the surface. Surface tension and currents bring two, or more, flowers together and pollination takes place. Once fertilized the female flower is drawn under the surface by the coiling scape and develops a fruit with many seeds.
Thanks to various wild forms, cultivars, and hybridizations (why is it considered OK to hybridize plants anyway?) it is difficult to identify, or even agree on, all the different species of Vallisneria. From all my reference material I managed to identify only five separate species and the descriptions follow. By the way, the surest way of differentiating Vallisneria from the grass-like species of Sagittaria is to check the leaf tips. They are serrated in Vallisneria and smooth in Sagittaria.
Vallisneria americana Michaux, 1803.
V. gigantea GRAEBNER, 1912.
V. natans var. biwaensis.
V. spiralis forma tortifolia WENDT, 1952.
V. torta WENDT.
The original V. americana has leaves up to 183 cm long and 1.9 cm wide and may show red leaf nervations. The male spathe is 1.6 cm long with three sepals. Female flowers have three petals and three sepals. Supposedly this plant stops growing in Winter even in aquaria. V. americana var. biwaensis, from Lake Biwa in Japan, has twisted leaves.
V. americana (gigantea), the jungle val, has leaves up to 91 cm long and 1.9 cm wide, with five to nine veins with longitudinal black and brown stripes. Female flowers are 2 to 3 cm long and the fruit is up to 20 cm long.
Vallisneria asiatica MIKI, 1934.
From Vietnam, Japan, and Taiwan. According to the Baensch Aquarium Atlas this species is widely cultured in aquaria and it has almost completely displaced V. spiralis, although the aquarium strain is usually identified as V. spiralis.
Leaves can reach 60 cm in length and about 1 cm in width, are not twisted though young leaves show some twisting. The male flowers have 1 stamen, actually a characteristic of V. americana. Female flowers have a 2 cm spathe, with petals 3-4 mm long and 3 reduced stamens. The fruit is up to 20 cm in length.
Vallisneria gracilis F. M. Bailey, 1889.
From Australia. Leaves are straight, up to 40 cm long and 4 mm wide. The male inflorescence reaches up to 4 mm in diameter. This is a much smaller plant in the wild, where it occurs in cool, nutrient poor waters.
Vallisneria neotropicalis Marie Victorin, 1943.
From Southern United States and Cuba, this is a large reddish species and may be the one referred to as V. rubra in some works. In the wild the leaves only reach about 35 cm in length and are blackish red. In aquaria the leaves are longer, up to 150 cm, with a width of up to 2.5 cm, deep green to reddish with dark red stripes running crosswise. There are five veins in each leaf, with the center one being thicker. The male flowers have three stamens. Female flowers have 4 to 4.5 mm long sepals and 1mm long petals.
Vallisneria spiralis LINNÉ, 1753.
V. spiralis forma nana
V. spiralis forma pusilla
V. spiralis forma gracilis
The leaves reach 60 cm in length and 4 to 7 mm in width, often twisting. Male flowers have two stamens. Female flowers are 1.5 cm long, have three stigmas and are attached to the plant via a spiraling scape.
Vals are easy to grow and once established they can easily take over a tank. They propagate vegetatively by runners. From the references and from personal experience, these plants do well in brightly-lit tanks, are fine in hard and alkaline water, and benefit from the addition of iron-based fertilizers. I find iron is the limiting factor for Vallisneria in my tanks. Regular iron fertilization results in faster, denser, growth and increases leaf width.
In nature Vallisneria are found in both running and still waters. The ribbon-shaped leaves move in the direction of the current for maximum exposure to light. Their fast growth makes them great oxygenators and nutrient removers in our aquaria. They are also very adaptable to their surroundings. For example the longest vals I had in a 50-L tank (less than 20 cm in depth) barely reached the surface. The same plants in a 50 cm deep and 150 cm long tank grew to be 80 cm long and doubled their leaf width. This versatility make them welcome additions to our aquaria.
That’s it for this month. Before I leave you though I have a trivia question: what Vallisneria isn’t a plant? The answer is on page 13 of this magazine. Hint: it isn’t a plastic Vallisneria.
*The frogbits, genera Hydrocharis and Limnobium, are also in the same family.
Riehl, Rüdiger, and Baensch, Hans A. (1986). Aquarium Atlas. Melle, Germany: MERGUS-Verlag.
Riehl, Rüdiger, and Baensch, Hans A. (1993). Aquarium Atlas Volume 2. Melle, Germany: MERGUS-Verlag.
Bailey, Liberty Hyde and Bailey, Ethel Zoe (1976). Hortus Third. New York: MacMillan Publishing Company.
Stodola, Jiri (1967). Encyclopedia of Aquarium Plants. Neptune City, New Jersey: T.F.H. Publications, Inc.
Stodola, Jiri (1987). Windeløv’s Tropica Catalogue, Aquarium Plants. Neptune City, New Jersey: T.F.H. Publications, Inc.
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