A Note on the Typification of Vallisneria spiralis (Hydrocharitaceae)

Abstract

Vallisneria spiralis L. is an aquatic species which is common and widespread in the tropics and warm temperate regions. It is also well-known in cultivation and is frequently planted as an oxygenator in tropical aquaria. While preparing an account of Hydrocharitaceae for Flora of Tropical East Africa, I was unable to find any reference to a type for this species, and since it is such a well-known plant it seemed desirable to investigate this further. In LINN there are two specimens (Savage Catalogue nos. 1157-1 and 1157-2) which, without doubt, can be assigned to V. spiralis. However these appear to have been collected after 1753, and as there is no reference to them in any of Linnaeus' work they must be discounted as possible type material. Before 1758, Vallisneria was described in Linnaeus' Hortus Cliffortianus (1738), Flora Lapponica (1737) and Genera Plantarum (1738). However there are no specimens of Vallisneria in Linnaeus' Lapland Herbarium at the Institut de France, Paris, nor in other herbaria containing Linnaean material (C. Jarvis pers. comm.). There is also a mention of it in van Royen's Florae Leydensis prodromus (1740) but, again, no specimen can be found in van Royen's herbarium at L. In Species Plantarum three polynomials are cited in synonymy. The first and third of these are taken from Micheli's Nova plantarum genera (1729), where they are accompanied by detailed and accurate illustrations in Plate 10, Figs. 1 & 2 of the book. Although Micheli believed that these polynomials described separate taxa, they do in fact refer respectively to the female and male plants of V. spiralis and this was correctly acknowledged by Linnaeus in Species Plantarum. Unfortunately there are no specimens corresponding to V. spiralis in Micheli's herbarium at FI. The second polynomial is quoted as being taken from Boccone's "Museo di piante rare della Sicilia", p. 289 (1697). However this would appear to be incorrect as Boccone's work only has 196 pages and there is no mention of any such polynomial in the index. The same polynomial and reference are given by Micheli, and therefore it is probable that Linnaeus obtained them from this source, and as a result the error was perpetuated in his own work. The correct source of this polynomial cannot be traced.