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

Jump to: Resources | Images | Distribution Maps | Sources
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

Selected Images from Invasive.orgView All Images at Invasive.org


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 and 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
 


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

Alternative content

Get Adobe Flash player





Invasive Listing Sources:
Alabama Invasive Plant Council
California Invasive Plant Council
Faith Campbell, 1998
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.