Malta starthistle USDA PLANTS Symbol: CEME2
U.S. Nativity: Exotic
Habit: Forbs/Herbs
Centaurea melitensis L.

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Taxonomic Rank: Magnoliopsida: Asterales: Asteraceae
Synonym(s): Maltese star-thistle, Malta starthistle, Maltese star thistle, Napa thistle, spotted knapweed, tocalote
Native Range: Afrcia, Europe (GRIN);

Appearance
Centaurea melitensis is a winter annual with a yellow-flowered, spiny head that can reach a height of 3.3 ft. (1 m). tall.
Foliage
Leaves are alternate, linear or narrowly oblong with smooth, toothed margins. Leaf bases are decurrent and give the stems a winged appearance.
Flowers
Flowers are yellow, 0.5 in. (1.3 cm) across, and surrounded by sharp, tan, 0.5 in. (1.3 cm) long, spiny cobwebbed bracts. Blooming occurs from April to September.
Fruit
The fruit are 0.08-0.12 in. (2-3 mm) in length, grayish to tan in color with deeply notched bases and tan bristles that are 0.04-0.12 in. (1-3 mm) long.
Ecological Threat
Centaurea melitensis prefers disturbed areas such as grasslands, open woodlands, roadsides, fields, and pastures. It is native to Europe and North America.

Identification, Biology, Control and Management Resources

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


Plant(s); Habit
Forest and Kim Starr, Starr Environmental, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
John M. Randall, The Nature Conservancy, Bugwood.org
Additional Resolutions & Image Usage

Flower(s); A flower
John M. Randall, The Nature Conservancy, Bugwood.org
Additional Resolutions & Image Usage

Feature(s); buds and flower head
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
Additional Resolutions & Image Usage

Flower(s); post senescence
Joseph M. DiTomaso, University of California - Davis, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s); The fruit attachment scar is clearly evident when the fruit is lying flat. Note the hairs along the fruit's surface.
D. Walters and C. Southwick, USDA, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s); Face (left) and lateral (right) views of two fruits.
D. Walters and C. Southwick, USDA, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s); Looking into the center of the outer pappus whorls to see the innermost whorl covering the stylar remains.
D. Walters and C. Southwick, USDA, 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.

U.S. National Parks where reported invasive:
Chiricahua National Monument (Arizona)
Death Valley National Park (California)
Haleakala National Park (Hawaii)
Organ Pipe National Monument (Arizona)
Sequoia and Kings Canyon National Parks (Californina)
Yosemite National Park (California)



Invasive Listing Sources:
California Invasive Plant Council
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007