Salix udensis (syn. S. sachalinensis F.Schmidt) is a species of willow native to northeastern Asia, in eastern Siberia (including Kamchatka), northeastern China, and northern Japan.
It is a deciduous shrub growing to tall. The leaves are slender, lanceolate, 6âÂÂ10 cm long and 0.8âÂÂ2 cm broad, glossy dark green above, glaucous and slightly hairy below, with a serrated margin. The flowers are produced in early spring on catkins 2âÂÂ3 cm long. It typically takes 20 years to reach maturity.
The cultivar S. udensis 'Sekka' (Japanese fantail willow) is grown as an ornamental plant; it has fasciated stems (stems that are joined abnormally in a flattened arrangementâÂÂhence "fantail"), highly prized by Ikebana flower arrangers. The Sekka cultivar has also been found to be resistant to plant pathogens such as rust (Melampsora spp.) caused by pathogenic fungi.