BugwoodWiki Article

musk thistle
Carduus nutans L.

Overview

Appearance
Carduus nutans is an herbaceous, biennial plant that grows to 6 ft. (1.8 m) tall. The stem has very spiny wings. Carduus species may hybridize with each other.
Foliage
Leaves are green and lanceolate to oblong-lanceolate. They are often pinnatifid and are very prickly. Leaves are usually sessile to slightly clasping. Basal leaves are 4-16 in. (10-40 cm) long. Leaf characteristics are variable across different varieties and subspecies.
Flowers
Showy, solitary, hemispherical, red to purple, disk flowers bloom from June to September. Phyllaries are spinetipped and overlap with several rows.
Fruit
Fruits are small achenes, 1.52 in. (45 mm) long, about 0.04 in. (1 mm) in diameter, including a white to light brown pappus. The seeds have longitudinal dotted stripes.
Ecological Threat
Carduus nutans invades a variety of disturbed areas. Pastures are particularly at risk because It is unpalatable to livestock. Once established it can spread rapidly due to high seed production (as much as 120,000 seed per plant). Carduus nutans is native to Western Europe and was accidentally introduced into the United States in the early 1900s.

General Description:

"Musk thistle" in the United States and Canada includes a complex of closely-related species of the Carduus nutans group. Species in this group are tall (up to 1.5m) facultatively biennial or annual herbaceous thistles with deeply lobed, spiny, decurrent leaves.

Diagnostic Characteristics:

Size and shape of the imbricate, spine-tipped involucral bracts is used to distinguish members of the group from closely related species and from each other.

Members of the genus Carduus are distinguished by their simple pappus hairs from members of the genus Cirsium, which have feathery, plumose pappus hairs. Within the genus Carduus, members of the nutans group are distinguished by their large nodding heads from closely related, small- flowered plumeless and Italian thistles (C. acanthoides, C. crispus, C. pycnocephalus, and C. tenuiflorus) (McCarty 1984, Mulligan and Frankton 1954, Trumble and Kok 1982).

Carduus thoermeri is distinguished from other members of the nutans group by the broad (4-8 mm) fairly short blade of the involucral bract, which converges to a short awn tip. Carduus macrocephalus is distinguished from other North American members of the nutans group by the raised mid-vein of the long, broad, uniformly tapering involucral bract. Carduus nutans conforms to the illustration in the 3rd edition of Britton and Brown's illustrated flora (Gleason 1957). The involucral appendage is much narrower than in other members of the group. The involucral blade is narrow (1.5-3 mm), more or less hairy, and tapers gradually to an awn. Carduus sp. from British Columbia is characterized by a broad, fairly short involucral bract, converging slowly but not uniformly to the tip (McCarty 1985, Tutin et al. 1976).

In addition to these morphologically distinct species, hybrids of intermediate appearance have been reported between Carduus sp X C. thoermeri, C. thoermeri X C. macrocephalus and Carduus nutans (sensu latu) X C. acanthoides (McCarty 1985, Moore and Mulligan 1956, 1964, Mulligan and Moore 1961).

Selected Images


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Carduus nutans
Flower(s)
James R. Allison
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Steve Dewey
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Plant(s)
Steve Dewey
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Foliage
Loke T. Kok
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Flower(s)
USDA APHIS PPQ Archive
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Flower(s)
Wendy VanDyk Evans
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Flower(s)
Ricky Layson
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Ricky Layson
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Steve Dewey
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Plant(s)
James H. Miller
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Stem(s)
Dan Tenaglia
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Feature(s)
Mary Ellen (Mel) Harte
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Plant(s)
Dan Tenaglia
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Plant(s)
Vince Belleci
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Infestation
Vince Belleci
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Infestation
Kris Johnson
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Infestation
Steve Dewey
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Infestation
Norman E. Rees
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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

Most Troublesome / Most Common Agricultural Weed List
This map identifies those states that consider this species either most troublesome or most common in at least one commodity. For more information, visit the MTMC project page.

State Regulated List
Legend
   No Data for this state
   Troublesome or Common weed in one or more crops

Invasive Listing Sources

Taxonomic Rank

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

Other System Links

Plants: CANU4
Bayer: CRUNU
GRIN: 104109
ITIS: 35787
NPDN Pest: PBFAQBC
NPDN Host: 28151

Synonyms and Other Names

Other Common Names:
nodding plumeless thistle, nodding thistle, bristle thistle

Related Scientific Names:

Carduus macrocephalus L.(Synonym)
Carduus macrolepis L.(Synonym)

Categories

Category: Forbs/Herbs