Flora of North America species comparison

Variety longistylis differs from var. alaxensis mainly in its glaucous and less densely hairy branchlets. Some specimens of var. alaxensis, in which the indumentum has been partially removed by wind erosion, show that they, too, have glaucous branchlets. The only fundamental difference between the two may be density of branchlet indumentum. Other differences, which appear in varietal descriptions, may represent inadequate sampling. These taxa sometimes intergrade and var. longistylis may not be worthy of taxonomic recognition. It is included here only because of very conspicuous differences between the extremes.

Hybrids:

Variety longistylis forms natural hybrids with Salix sitchensis.

Variety longistylis × Salix sitchensis grows with both parents at the mouth of the Twentyfour Mile River, south-central Alaska. The plants resemble var. longistylis in having relatively long styles and stigmas, oblong nectaries, and sparsely hairy branchlets, and S. sitchensis in having brittle branches, weakly glaucous branchlets, hairs sparse and crinkled, and ovaries with straight hairs. Fruits were set but no seed developed.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Variety alaxensis is one of the tallest “trees” in the Canadian Arctic. An extensive stand of willows, some of which reach tree-size, occurs in a valley on deep marine, lake, or river gravels and sands southeast of Deception Bay in northern Ungava, Quebec (P. F. Maycock and J. B. Matthews 1966). The largest of the dominant willows of tree stature, var. alaxensis and Salix planifolia were ca. 5 m tall and 20 cm in diameter. The maximum age for a stem 10 cm in diameter was 60 years, but at this age there was heartwood decay. An outlier stand of tree-sized willows on Victoria Island, Northwest Territories, reached 6–8 m, to 81 years of age (S. A. Edlund and P. A. Egginton 1984).

Hybrids:

Variety alaxensis forms natural hybrids with Salix calcicola, S. drummondiana, S. pellita, and S. planifolia.

Variety alaxensis × Salix calcicola was discovered by M. Blondeau at Kangigsujuak, Quebec. The plants resemble S. calcicola in having broad leaves and stipules, and reddish styles, and var. alaxensis in having densely villous leaves and branchlets, and relatively short pistillate flowering branchlets. The ovaries have hairy beaks or are sparsely hairy throughout.

Variety alaxensis × Salix drummondiana: In the northern Rocky Mountains, plants resembling S. drummondiana but with stipules prominent, linear or lanceolate, and foliaceous, and leaves abaxially densely woolly may be this hybrid.

Variety alaxensis × Salix pellita occurs in the Churchill, Manitoba, region where it grows with var. alaxensis, S. pellita, and S. planifolia. The plants resemble var. alaxensis in having very densely villous branchlets, and leaves with short wavy hairs on abaxial surfaces. The leaf indumentum is sparse, and ferruginous hairs often occur on juvenile and late leaves. Strongly revolute margins suggest S. pellita as the second parent.

Variety alaxensis × Salix planifolia occurs in the Churchill, Manitoba, region where it grows with the two parental species. It resembles var. alaxensis in its very densely villous branchlets and leaves with short wavy hairs on abaxial surfaces. Leaf indumentum is sparse, and ferruginous hairs often occur on juvenile and late leaves.

(Discussion copyrighted by Flora of North America; reprinted with permission.)