Panarctic Flora


580241b Salix lanata var. glandulosa Wahlenb.


Northern Fennoscandia: Scattered
Shrub Tundra: Rare
Bordering boreal or alpine areas: Scattered


2n= 38 (2x). - Europe (N). - Marklund in Holmberg (1931).

Geography: European (N): NOR RUS.

Notes: Salix lanata var. glandulosa (S. glandulifera) is enigmatic. It differs from S. lanata s. str. in some assumed independently inherited characters, e.g., all leaves and bracts marginally densely glandular or glandular-dentate vs. eglandular and entire, leaves thinner, more narrow and less hairy, and shrubs often much taller. The differences seem to be at least as pronounced as between S. lanata and S. calcicola (across the Atlantic). For a different opinion, see Skvortsov (1966) who concluded that "The distinguishing characters attributed to S. glandulifera Flod. (better development of dentation on the margins of the leaves and stipules) are extremely inconstant and not correlated with any other morphological and ecological differences of any kind, so that recognition of S. glandulifera as of species rank is inconceivable" (translated in Tolmachev et al. 2000). Skvortsov's insistence on dentate leaves in Russian S. lanata may suggest that S. glandulifera (or var. glandulosa) is the predominant plant in Russia, whereas S. lanata s. str. may be the plant of the major parts of Scandinavia and of Iceland (and Svalbard).

The problem is the distribution pattern in Fennoscandia and the suggested extensive hybridization with S. lanata s. str. Variety glandulosa has a sparse and disjunct occurrence within the range of S. lanata s. str. It may dominate locally but stands of pure plants are rare, whereas assumed hybrid swarms are very frequent. The entire Icelandic population is slightly glandular even if it is much closer to S. lanata s. str. in all other features. This case does not fit the criteria of any rank. Salix glandulifera is much too interfertile and thoroughly hybridized with S. lanata to be a 'good' species, it does not have a separate geographical and/or eco-geographical range justifying a subspecies (at least not in Fennoscandia), and it is neither ecotypical nor local, i.e., not a 'good' variety according to our criteria. The strange pattern may have a historical background. There might once have been two morphologically distinct and allopatric species but postglacial migrations may have brought them into sympatry. The rarer one (S. glandulifera) is now being hybridized away - by introgression in the strict meaning of the concept - into the more common one (S. lanata), at least in Scandinavia and Iceland. The process seems to be complete in Iceland, whereas some nodes of 'pure' S. glandulifera remain in Fennoscandia.

Higher Taxa