BugwoodWiki Article

blessed milkthistle
Silybum marianum (L.) Gaertn.

Overview

Appearance
Silybum marianum is an annual or biennial herb that ranges from 2-6 ft. (0.6-1.8 m) in height.
Foliage
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.
Flowers
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
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.

General Description:

Silybum marianum is an erect, annual (or biennial in California) herb growing from one to two meters tall with solitary purple flower heads 2.5-5 cm across.

Diagnostic Characteristics:

Silybum marianum can be distinguished from other California thistles by its distinctive white-mottled leaves. There is only one species of Silybum established in California. "The seed leaves (cotyledons) are large from 1/2 to 3/4 inch wide and 3/4 to 1 inch long, rather thick, succulent and light green. The first leaves are very conspicuously white-netted along the veins and have short yellowish prickles".

Resources

Selected Images


1116030
1116030

blessed milkthistle
Silybum marianum
Foliage
Charles T. Bryson
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5341043

blessed milkthistle
Silybum marianum
Flower(s)
Jan Samanek
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5391767

blessed milkthistle
Silybum marianum
Foliage
Barry Rice
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5341047

blessed milkthistle
Silybum marianum
Seed(s)
Jan Samanek
5341044
5341044

blessed milkthistle
Silybum marianum
Flower(s)
Jan Samanek
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5341045

blessed milkthistle
Silybum marianum
Plant(s)
Jan Samanek
5341042
5341042

blessed milkthistle
Silybum marianum
Infestation
Jan Samanek
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5287078

blessed milkthistle
Silybum marianum
Plant(s)
Forest and Kim Starr
1116029
1116029

blessed milkthistle
Silybum marianum
Plant(s)
Charles T. Bryson
5341040
5341040

blessed milkthistle
Silybum marianum
Plant(s)
Jan Samanek
5341046
5341046

blessed milkthistle
Silybum marianum
Infestation
Jan Samanek
5308007
5308007

blessed milkthistle
Silybum marianum
Plant(s)
USDA PLANTS Database

Maps


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

EDDMapS Distribution

State Regulated List - This map identifies those states that list this species on their regulated list. For more information, visit Invasive.org

State Regulated List

Taxonomic Rank

Kingdom: Plantae
Phylum: Magnoliophyta
Class: Magnoliopsida
Subclass: Asteridae
Order: Asterales
Family: Asteraceae
Genus: Silybum

Other System Links

Plants: SIMA3
Bayer: SLYMA
GRIN: 33952
ITIS: 38413
NPDN Pest: PBFDABA
NPDN Host: 36255

Synonyms and Other Names

Other Common Names:
blessed milk-thistle, milk thistle, spotted thistle, variegated thistle

Related Scientific Names:

Carduus marianus (L.) Gaertn.(Synonym)
Mariana marianum (L.) Gaertn.(Synonym)

Categories

Category: Forbs/Herbs