Milk thistle
2007 Schools Wikipedia Selection. Related subjects: Plants
| iMilk Thistle | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
 Silybum marianum
|
||||||||||||||||
| Scientific classification | ||||||||||||||||
|
||||||||||||||||
|
|
||||||||||||||||
|
Milk thistles are thistles of the genus Silybum Adans., flowering plants of the daisy family ( Asteraceae). They are native to the Mediterranean regions of Europe, North Africa and the Middle East.
Members of this genus grow as annual or biennial plants. The erect stem is tall, branched and furrowed but not spiny. The large, alternate leaves are waxy-lobed, toothed and thorny, as in other genera of thistle. The lower leaves are cauline (= attached to the stem without petiole). The upper leaves have a clasping base. They have large, disc-shaped pink-to-purple, rarely white, solitary flower heads at the end of the stem. The flowers consist of tubular florets. The phyllaries under the flowers occur in many rows, with the outer row with spine-tipped lobes and apical spines. The fruit is a black achene with a white pappus.
Only two species are currently classified in this genus:
- Silybum eburneum Coss. & Dur., known as the Silver Milk Thistle, Elephant Thistle, or Ivory Thistle
- Silybum eburneum Coss. & Dur. var. hispanicum
- Silybum marianum (L.) Gaertner, the Blessed Milk Thistle, which has a large number of other common names, such as Variegated Thistle.
The two species hybridise naturally, the hybrid being known as Silybum × gonzaloi Cantó , Sánchez Mata & Rivas Mart. (S. eburneum var. hispanicum x S. marianum)
A number of other plants have been classified in this genus in the past but have since been relocated elsewhere in the light of additional research.
S. marianum is by far the more widely known species. It is believed to give some remedy for liver diseases(e.g. viral hepatitis) and an extract, silymarin, is used in medicine. The adverse effect of the medicinal use of milk thistle is loose stools.