WHO monographs on selected medicinal plants - travolekar.ru

<strong>WHO</strong> <strong>monographs</strong> on selected medicinal plants
to widely obovate, margins entire to serrulate. Leaf underside is generally
hairy or glaucous, rarely glabrous. Inflorescence consists of small unisexual
catkins emerging, depending on species, either before, at the same
time as, or after the leaves emerge; individual flowers inconspicuous,
apetalous, subtended by a single fringed or hairy bract; sepals replaced by
nectaries. Stamens 1–8, often 2 in staminate flower, and in pistillate flowers,
the ovary is superior, bicarpellate, unilocular; style 1; stigmas 2, each
0–2-lobed. Fruit capsule, two-valved. Seeds many, comose (1). Salix alba
is a large tree with a short trunk, yellowish-brown branches and ellipticlanceolate,
acuminate and serrulate, ash-grey, sericious leaves. The fruit is
a capsule dehiscent by 2 valves and contains numerous seeds, on each of
which is a basal tuft of hair (11).
Plant material of interest: dried branch bark
General appearance
The bark is 1–2 cm wide and 1–2 mm thick and occurs in flexible, elongated,
quilled or curved pieces. The outer surface is smooth or slightly wrinkled
longitudinally and greenish-yellow in the younger bark to brownishgrey
in the older bark. The inner surface is smooth or finely striated
longitudinally and white, pale yellow or reddish-brown, depending on the
species. The fracture is short in the outer part and coarsely fibrous in the
inner region, and is easily split longitudinally. The diameter of current year
twigs is not more than 10 mm. The wood is white or pale yellow (2, 4).
Organoleptic properties
Odour: slight; taste: astringent and bitter (1, 2, 4).
Microscopic characteristics
Two or three rows of poorly developed cork cells with thickened outer
walls; cortex of collenchymatous and parenchymatous cells. The latter
contain cluster crystals of calcium oxalate, 20–25 μm in diameter and occasionally
tannin. Phloem is characterized by tangential groups of lignified
fibres associated with a crystal sheath containing prismatic crystals of
calcium oxalate. Simple, rounded starch granules 6–8 μm in diameter in
the parenchymatous cells of the phloem and medullary rays (2).
Powdered plant material
Pale yellow, greenish-yellow or light brown. Microscopically, bundles of
narrow fibres, up to about 600 μm long, with very thick walls, lignified,
and surrounded by a crystal sheath containing prism crystals of calcium
oxalate; parenchyma of the cortex with thick, pitted and deeply beaded
walls, and containing large cluster crystals of calcium oxalate; uniseriate
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