- Silybum marianum is an annual or biennial herb that ranges from 2-6 ft. (0.6-1.8 m) in height.
- Leaves have shiny, green upper surfaces and are noticeably variegated with white markings. Basal leaves are 6-28 in. (15.2-71.1 cm) long with spiny margins. Much smaller stem leaves clasp the stem.
- Purple thistle flower heads develop at the apex of the stems. They are 0.8-2.5 in. (2-6.4 cm) in diameter at the base and are enclosed in a projecting, spiny involucre. Flowers from April to July.
- Fruit are black and brown achenes that are about 0.3 in. (0.85 cm) long, slightly flattened with a ring of bristles at the apex.
- Ecological Threat
- S. marianum invades roadsides, ditches, disturbed areas and fertile fields. It is native to the Mediterranean region. S. marianum can be poisonous to livestock, especially during periods of wilt from drought, mowing or herbicide treatment.
- Element Stewardship Abstract - The Nature Conservancy
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EDDMapS Distribution - This map is incomplete and is based only on current site and county level reports made by experts, herbaria, and literature. For more information, visit www.eddmaps.org
State Invasive List - This map identifies those states that list this species on their invasive species list. For more information, visit Invasive.org
Invasive Listing Sources
Other System LinksPlants: SIMA3
NPDN Pest: PBFDABA
NPDN Host: 36255
|Common Name Reference:|| USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.|
|Scientific Name Reference:||USDA, NRCS. 2010. The PLANTS Database. National Plant Data Center, Baton Rouge, LA, USA.|