Polar willow
| Polar willow | ||||||||||||
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Polar willow ( Salix polaris ) |
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| Salix polaris | ||||||||||||
| Election b. |
The polar willow ( Salix Polaris ) is a plant from the genus of willow ( Salix ) within the family of the pasture plants (Salicaceae).
description
Appearance, bark and leaf
The polar willow grows as a small, creeping, deciduous shrub (espalier shrub ), which typically reaches heights of 1 to 9 cm, rarely up to 15 cm. It forms flat mats through rhizomes or stolons . Upright main branches are formed. The bark of the branches is red-brown, thin to thickly frosted and bare. The bark of the branches is brownish bare and not frosted.
The alternate leaves arranged on the branches are divided into a petiole and a leaf blade. The 2 to 10 mm long, bald petiole has no glands and is deeply concave in cross section, but the edges do not cover the furrow. The mostly dark green, herbaceous to leathery, flat leaf blade is circular with a length of 5 to 32 mm and a width of 8 to 18 mm, more or less broadly elliptical or obovate, with a length-to-width ratio of 1.1 to 2.8. The base of the stretcher tapers, is wedge-shaped or blunt. The upper end of the leaf blade is rounded, pointed, or sometimes obtuse. The leaf margin is smooth. The upper side of the leaf is shiny and mostly bare. Stomata are located on both sides of the leaf. The leaves of young plant specimens are yellowish-green and bare and the underside of the leaves is not frosted and usually bare, rarely it has long straight hairs ( trichomes ). In autumn the leaves turn yellow. If stipules are present, then they are scale-like.
Inflorescences, flowers and fruits
The polar willow is dioecious separate sexes ( diocesan ). Before the leaves shoot when the leaf buds open, one to a few kitten-shaped inflorescences appear at the tips of the previous year's growth, each with only a few flowers . The male catkins are stocky with a length of 6 to 27 mm and a width of 6 to 12 mm, more or less spherical and contain densely packed flowers; they are on 1.5 to 14 mm long flower stems on 1.5 to 9 mm long inflorescence shafts. The female catkins are stocky with a length of 10 to 35 mm and a width of 7 to 13 mm, more or less spherical and contain the flowers more or less densely packed; they are on 1 to 12 mm long flower stems on 2 to 12 mm long inflorescence shafts. The brown to black or two-colored, entire-margined bracts have a length of 1.5 to 2.5 mm and are broadest in the middle or at the tip; they are bald or sparsely covered with straight or wavy hair all over. The male flowers usually have a nectar gland each above and below. The two stamens have a bare stamen. The initially purple-colored later yellow anthers are ellipsoidal or egg-shaped with a length of 0.4 to 0.6 mm. 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 stylus ends with a narrow, cylindrical scar with 0.4 to 0.72 mm long lobes.
The brownish, bald capsule fruits are 5 to 7 mm long.
Chromosome number
The chromosome numbers are 2n = 76 and 114. Tetraploidy and hexaploidy were detected in degrees of ploidy .
distribution
The natural range of the Arctic Willow extends in a circumpolar manner over the tundras of Europe , North America and Asia . But you can also find them in the mountainous regions of Norway , Svalbard and British Columbia ( Canada ). The southernmost locations today reach up to 60 ° N.
Systematics
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 subsp. pseudo Polaris (Flod.) Hultén , Salix Polaris var. glabrata Hultén , Salix Polaris var. selwynensis Raup , Salix pseudo Polaris Flod.
swell
- Salix polaris in GW Argus, CL McJannet & MJ Dallwitz: Salicaceae of the Canadian Arctic Archipelago near DELTA. ( Memento of March 14, 2012 in the Internet Archive ) (section description, distribution and systematics)
Individual evidence
Web links
- Entry at GRIN.
- Entry in the Flora Europaea.
- Distribution in the northern hemisphere according to: Eric Hultén , Magnus Fries: Atlas of North European vascular plants 1986, ISBN 3-87429-263-0
