Silybum marianum is a species of thistle. It has various common names including milk thistle, blessed milkthistle, Marian thistle, Mary thistle, Saint Mary's thistle, Mediterranean milk thistle, variegated thistle and Scotch thistle (not to be confused with Onopordum acanthium or Cirsium vulgare). This species is an annual or biennial plant of the family Asteraceae. This fairly typical thistle has red to purple flowers and shiny pale green leaves with white veins. Once native from Southern Europe through Asia, it has spread throughout the world.
Description
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Milk thistle is an upright herb that can grow to be 30 to 200 cm (12 to 79 in) tall and has an overall conical shape. The approximate maximum base diameter is 160 cm (63 in). The stem is grooved and may be covered in a light cottony fuzz. The largest specimens have hollow stems.
The leaves are oblong to lanceolate and
The flower heads are 4 to 12 cm long and wide, of red-purple colour. They flower from June to August in the North or December to February in the Southern Hemisphere. The flower head is surround by bracts which are hairless, with triangular, spine-edged appendages, tipped with a stout yellow spine.
The fruits are black achenes with a simple long white pappus, surrounded by a yellow basal ring. A long pappus acts as a "parachute", supporting seed dispersal by wind.
