Salix polaris
Polar willow ( Salix polaris )
The Polar willow ( Salix polaris ) is a plant of the genus willow ( Salix) within the family of the willow family ( Salicaceae ).
- 4.1 Notes and references
Description
Appearance, bark and leaf
The Polar willow grows as a small, creeping, deciduous shrub ( trellis vine), the typical plant height 1-9 cm is reached, rarely up to 15 cm. It forms by rhizomes or stolons and mats. There shall be set upright main branches. The bark of the branches is reddish brown, thin frosting until thick and bald. The bark of the branches is brownish bald and not frosted.
The alternate arranged on the branches leaves are divided into petiole and leaf blade. Of 2 to 10 mm long, has no bare petiole glands and is deeply concave in cross-section, but the edges are not covering the furrow. The usually dark green, herbaceous to leathery, flat leaf blade is circular with a length of 5 to 32 mm and a width of 8-18 mm, more or less broadly elliptic or obovate, with a length to width ratio of 1.1 to 2.8. The Spreitenbasis runs from pointed, wedge-shaped or blunt. The upper end of the leaf blade is rounded, pointed or blunt sometimes. The leaf margin is smooth. The upper leaf surface is shiny and mostly bare. Stomata are located on both leaf surfaces. On young plants copies the leaves are yellowish- green and glabrous and the lower leaf surface is frosted and usually glabrous, rarely has long straight hairs ( trichomes ). In the autumn the leaves turn yellow. If stipules are present, then they are scale-like.
Inflorescences, flowers and fruits
The Arctic willow is dioecious getrenntgeschlechtig ( dioecious ). Before the leaves when opening the leaf buds appear at the tips of last year's growth to a few kitten shaped inflorescences with only a few flowers. Male kittens are penetrated at a length of 6 to 27 mm and a width of 6 to 12 mm, more or less spherical in shape and comprise closely packed the flowers; they are of 1,5 up to 14 mm long flower stems to 1.5 to 9 mm long Blütenstandsschäften. Female kittens are penetrated at a length of 10 to 35 mm and a width of 7 mm to 13 mm, more or less spherical and contain more or less tightly packed, the flowers; they stand at 1-12 mm long flower stems to 2 to 12 mm long Blütenstandsschäften. The brown to black or two-tone, ganzrandigen bracts have a length of 1.5 to 2.5 mm and are widest in the middle or at the top; they are covered bare or sparsely over the entire surface with straight or wavy hair. The male flowers usually have the top and bottom a nectar gland. The two stamens have a bare filament. The initially purple later yellow anthers are at a length from0, 4 to 0.6 mm ellipsoid or ovoid. The female flowers are 0.8 to 1.4 mm long. The hairy ovary contains ten to twelve ovules. The 0.7 to 1.6 mm long style ends of a narrow - cylindrical scar 0.4 to 0.72 mm long lobes.
The brownish bald cap fruits have a length of 5 to 7 mm.
Chromosome number
The chromosome numbers be 2n = 76 and 114 at Ploidiegraden tetraploid and Hexaploidie were detected.
Dissemination
The natural range of the Arctic willow extends over the circumpolar tundra Europe, North America and Asia. But they are also found in the mountainous areas of Norway, Spitsbergen and British Columbia ( Canada). The southernmost localities ranging up to 60 ° N.
System
The first description of Salix polaris was made in 1812 by Göran Wahlberg in Flora Lapponica, pp. 261-262, Plate 13, Figure 1 synonyms for Salix polaris Wahlenb. are: Salix polaris Wahlenb. subsp. pseudo polaris ( Flod. ) Hultén, Salix polaris Wahlenb. var glabrata Hultén, Salix polaris Wahlenb. var selwynensis Raup, Salix polaris pseudo Flod ..
Swell
- Salix polaris in G.W. Argus, C. L. McJannet & M. J. Dallwitz: Salicaceae of the Canadian Arctic Archipelago at DELTA. (Section Description, distribution and systematics)