blessed milkthistle	USDA PLANTS Symbol: SIMA3 U.S. Nativity: Exotic Habit: Forbs/Herbs
Silybum marianum (L.) Gaertn.

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): blessed milk-thistle, milk thistle, spotted thistle, variegated thistle
Native Range: Mediterranean region ()
Blessed milkthistle is an annual/biennial herb native to the Mediterranean region. Plants range from 2-6 ft. (0.6-1.8 m) in height, depending on soil moisture. Leaves have shiny, green upper surfaces and are noticeably variegated with white markings. Basal leaves are 6-28 in. (15-70 cm) long with spiny margins. Much smaller cauline (stem) leaves clasp the stem. Flowering occurs from April to July, when purple thistle flower heads develop at the apex of the stems. Flower heads are 0.8-2.5 in. (2-6 cm) in diameter at the base and are enclosed in a projecting, spiny involucre. Fruit are black and brown achenes that are approximately 1/3 in. (6-8 mm) long, slightly flattened with a ring of bristles at the apex. Plants invade roadsides, ditches, disturbed areas and fertile fields. Milk thistle can be poisonous to livestock, especially during periods of wilt from drought, mowing or herbicide treatment.

Identification, Biology, Control and Management Resources

Element Stewardship Abstract - The Nature Conservancy

Selected Images from Invasive.org

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Foliage; Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org Additional Resolutions & Image Usage	Flower(s); Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Foliage; Barry Rice, sarracenia.com, Bugwood.org Additional Resolutions & Image Usage	Seed(s); Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage
Flower(s); Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Plant(s); in flower Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Infestation; Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Plant(s); habit Forest & Kim Starr, Starr Environmental, Bugwood.org Additional Resolutions & Image Usage
Plant(s); Charles T. Bryson, USDA Agricultural Research Service, Bugwood.org Additional Resolutions & Image Usage	Plant(s); Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Infestation; Jan Samanek, State Phytosanitary Administration, Bugwood.org Additional Resolutions & Image Usage	Plant(s); Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 3: 555. USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org

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State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

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Invasive Listing Sources:

Alabama Invasive Plant Council

California Invasive Plant Council

Faith Campbell, 1998

John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.