NIS - libdoc.who.int - World Health Organization

Herba Equiseti
nate) scales, forming a specific vaginate structure in the nodes of the
branches, which is usually called a “sheath” (1, 2, 28, 29).
Organoleptic properties
Odour: slight or no odour; taste: slightly acidic or no taste (2, 28, 29).
Microscopic characteristics
Epidermis with elongated, wavy-walled cells, silicified, often thickened
and beaded. The paracytic stomata with the 2 subsidiary cells cover the
guard cells and have conspicuous radial ridges. In transverse sectional
view the epidermis is crenate, with the protuberances formed from the
contiguous mass of 2 U-shaped cells. (No single-celled protuberances
should be present – absence of E. palustre L.) The cortex of stems of
thin-walled cells with many large lacunae; non-lignified, collenchymatous
fibrous cells up to 1 mm long with oblique or bifurcate apices in the
ridges; xylem of lignified, annularly or spirally thickened vessels occurring
singly or in small groups; slightly lignified annularly thickened tracheids
and bundles of long non-lignified fibres with narrow lumens.
Large parenchymatous cells packed with minute starch grains; large
central cavity. Branches have four vascular bundles and lack a central
cavity; the silicified collenchyma is reduced, cortex lacunae are absent
(1, 28–31).
Powdered plant material
Greenish-grey or dull green. The powder shows characteristic elements
of stems (see Microscopic characteristics) (1, 28, 29).
General identity tests
Macroscopic and microscopic examinations, and thin-layer chromatography
for the characteristic constituents: caffeic acid, hyperoside and rutin
(1, 28), quercetin 3-glucoside (5) and flavone-5-glucosides (2).
Purity tests
Microbiological
Tests for specific microorganisms and microbial contamination limits are
as described in the WHO guidelines on quality control methods for medicinal
plants (32).
Chemical
No information available.
115