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Silybum
marianum (L.) Gaertn.
Standardized Common
Name: Milk
Thistle
Other Common Names: Lady’s Thistle,
Marian Thistle, Mary’s Thistle, Spotted Thistle
Family: Asteraceae
(Compositae)
Taxonomy: Silybum
includes two species of thistle. Both are native to the Mediterranean; S.
marianum has become a wide-ranging weed.
Description: Annual or biennial
herb, 0.2–1.5 m high. Leaves in basal rosette and cauline; basal leaves 25–50
cm long, petiolate, coarsely pinnatisect; cauline leaves sessile with
auriculate bases, unlobed or pinnatilobed, glabrous, dark green with white
veins or spots; margins denticulate, bearing spines up to 8 mm long.
Inflorescences terminal heads (capitula), ovoid, 2.5–4 cm wide; receptacular
bracts (phyllaries) variable in shape, most ending in recurved spines 2–5 cm
long; receptacle hairy. Florets all disk florets, hermaphroditic, purple;
corolla tubular, 3–4 cm long, the uppermost portion widening abruptly and
5-lobed; pappus a single ring of white to pale yellow hairs, (11–)15–20 mm
long, fused at the base; anthers and style purplish. Fruit an achene
(technically a cypsela), narrowly obovate to oblong, 6–7(–8) mm long, 2.5–3(–4)
mm broad, with small collar at apex, varying from pale grayish brown to deep
brown or black, often mottled.
Parts in Commerce: Fruits
Identification:
- 6–7(–8) mm long,
narrowly obovate to oblong, somewhat flattened
- Base narrower
than apex, with hilum to one side, not sharply indented or curved
- Apex somewhat asymmetrical,
with circular yellow collar (remains of pappus base), style base
protruding beyond collar
- Surface shiny,
smooth, not with conspicuous longitudinal ridge(s)
- Color pale
grey-brown to blackish brown, often mottled and appearing streaky under
magnification
- Taste oily,
bitter
- Pappus (usually
missing) is a single ring of hairs, 11–20 mm long, white to pale yellow,
fused at base and easily detached from fruit
References:
British Herbal Medicine
Association. British Herbal Pharmacopoeia. BHMA; 1996:134–135.
do Amaral Franco J. Silybum. In: Tutin TG, Heywood VH, Burges NA, et al.,
eds. Flora Europaea. Vol. 4. Cambridge: Cambridge University
Press; 1976:126.
von Mueller F. Illustrated Description of
Thistles, etc., Included Within the Provisions of the Thistle Act of 1890.
Melbourne, Australia: Robt. S. Brain, Govt. Printer; 1893.
Wichtl M, ed. Herbal Drugs and
Phytopharmaceuticals, 3rd English
ed. Stuttgart: medpharm Scientific Publishers and Boca Raton, FL: CRC Press;
2004:107–111.
World Health Organization.
WHO Monographs on
Selected Medicinal Plants.
Vol. 2. Geneva: World Health Organization; 1999–2002:300–316.
Figure 69: Silybum marianum fruit.
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