WILLOW 287 



dextrose. Boiled with dilute sulphuric acid it yields saliretin and dextrose. 

 Cautiously heated with dilute sulphuric acid and potassium bichromate, 

 salicylic aldehyde with an odour of meadow sweet is evolved. 



The student should observe 



(a) The greenish or greyish brown colour ; 



(b) The smooth or wrinkled outer surface ; 



(c) The pale reddish inner surface ; 



and should compare this bark with 



(i) Oak bark, which has a silvery cork and dark brown inner 



surface ; 



(ii) Witch-hazel bark, which has a pale greyish cork and reddish 

 pink inner surface. 



Uses. Willow bark is astringent and has been used in rheumatism 

 and ague ; it has, however, been completely replaced by salicin. 



Allied Species. Salix discolor, Muehlenberg, and S. nigra, Marsh, yield 

 black willow bark which occurs in long, thin, tough, fibrous strips ; brownish 

 or greenish brown externally ; taste bitter, astringent, somewhat aromatic ; 

 contains tannin (about 4 per cent.) and salinigrin (about 1 per cent.) a colourless, 

 crystalline glucoside. 



Different species of the genus Salix are known as willows, osiers, and sallows. 

 The name willow is generally applied to those species that form trees, osiers 

 to those that form long slender shoots with few. lateral branches, and sallows 

 to those that have a shrubby growth. 



The chief willows are S. alba, the wood of which is used for making cricket- 

 bats, chip-boxes, &c., S. triandra, which is often pollarded close to the ground 

 to give long shoots (also called osiers) for white basket work, and S. fragilis, 

 Linne, the shoots from which have a reddish colour. S. fragilis is largely grown 

 in Belgium, and the bark peeled from the shoots constitutes the ' rood scorce ' 

 (i.e. red bark) from which salicin is made. Rood scorce is largely imported 

 into this country for that purpose, and contains about 3 per cent, of salicin. 



The chief osiers are S. viminalis, which is used for hampers, S. vitellina, which 

 is employed for binding, and S. purpurea, which is used for fine basket work. 

 The bark of the last-named species is especially rich in salicin, containing 6 or 

 7 per cent, of salicin. The bulk of the salicin employed medicinally appears, 

 however, to be made from S. fragilis. 



BARKS IN LESS FREQUENT USE 



Indian Azadirach (Neem Bark ; Margosa Bark). The dried stem-bark of 

 Melia Azadirachta, Linne (N.O. Meliacece), a tree indigenous to India and Malay 

 Archipelago. Channelled, tough, fibrous pieces up to 10 mm. thick. Exter- 

 nally brownish grey, rough and scaly or fissured ; internally yellowish, con- 

 spicuously laminated and coarsely fibrous. Transverse section minutely 

 chequered, pale narrow medullary rays and tangential bands of parenchyma 

 alternating with darker groups of bast fibres. Under the microscope the latter 



