Vallisneria asiatica var. biwaensis

The Lake Biwa vallisneria is a delicate, relatively low-growing variety of Vallisneria asiatica with spirally twisted leaves, which originates from Lake Biwa in Japan. As an aquarium plant it was introduced to Germany by the company Dennerle in 1991. According to information from Dennerle, this vallisneria occurs in Lake Biwa in large numbers in sunny spots in shallow water.¹

The species Vallisneria asiatica was synonymised with Vallisneria americana by R.M. Lowden in 1982. Accordingly, the Lake Biwa vallisneria was also called V. americana var. biwaensis. The molecular systematic study by Les & others (2008) showed that V. asiatica is not more closely related to the true, North American V. americana. It is, however, very close to the Asian Vallisneria natans and is treated by various authors as a synonym of that species. Vallisneria asiatica does differ from V. natans in some variable characters, e.g. narrower, shorter leaves and the absence of reddish colouration.²

Les & others (2008) examined many cultivated origins of vallisnerias and were unable to demonstrate the nominate form of V. asiatica among them, only the variety biwaensis.² The nominate form (Vallisneria asiatica var. asiatica) is therefore possibly not cultivated as an aquarium plant. It has smooth leaves and is likely to be difficult to distinguish from Vallisneria spiralis (of which there are also forms with twisted leaves).

The twisted leaves of V. asiatica var. biwaensis are quite narrow (3-5 mm wide) and, according to information from the company Tropica, can reach a length of 5 to 50 cm. In Christel Kasselmann's aquarium the plant has reached a height of 20 to 40 cm.¹

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