Panarctic Flora

240301 Zannichellia palustris subsp. palustris L.

2n= (1) 24 (4x). - Europe, Far East (N), New Zealand. - Several reports.
(2) 28. - Europe (Germany). - Reese in Löve and Löve (1961d).
(3) 32 34 36 (6x). - Europe, Canada. - Several reports.

Geography: Cosmopolitan: (ICE) ALA CAN.

Notes: Elven and Solstad: Haynes and Hellquist (2000d) mapped Zannichellia palustris in Alaska only from Valdez on the southern coast. Hultén (1968a) mapped it from the Arctic at Kotzebue on the western coast, and we have found it in 1999 and 2001 in arctic sites on the Seward Peninsula and northwest of Kotzebue (ALA, O).

Elven: Zannichellia palustris s. lat. is polymorphic and also varies in chromosome number. Many authors consider the variation within one species (e.g., Haynes and Hellquist 2000d, for North America), others as a series of species (e.g., Tzvelev 2000a with four species in northwestern European Russia; Tzvelev 1987g with three species in the Russian Far East). The plant probably most worthy of rank is subsp. polycarpa (Nolte) K. Richt. (Z. major Boenn. ex Rchb.) but this plant has not been reported from the Arctic. Tzvelev (PAF proposal) accepted subsp. palustris from Iceland and subsp. repens from Alaska. Tzvelev (in comment) would prefer to treat them as two species or subspecies ecologically separated by water salinity. Elven (in comment) agrees that the proposed taxa differ in characters often assumed to be taxonomically significant - mostly in size and shape of the reproductive parts - but they often occur mixed in stands, e.g., in northeastern Norway where subsp. palustris s. str. and subsp. repens grow together in the two isolated, subarctic localities. Co-occurence may, however, be explained by predominant bird dispersal. As those two subspecies are synonymized in the majority of recent sources (e.g., Markgraf and Zoller 1981), and as Zannichellia only reaches the Arctic at a very few localities, we treat the arctic plants collectively. A split into several species or subspecies should be based on some genetic and molecular evidence in addition to the morphological indications.