Yellow Star Thistle Centaurea solstitialis
Other Common Name(s):
- Phonetic Spelling
- sen-TAR-ee-uh sol-sti-shee-AL-liss
- Description
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Yellow star thistle is a winter annual in the Asteraceae (daisy) family native to southern Europe and North Africa. Genus name Centaurea came from the popular name of various plants in the late 14th century, from Medieval Latin centaurea, from Latin centaureum, from Greek kentaureion, meaning "centaur", so called because the plant's medicinal properties were discovered by Chiron the centaur. Specific epithet solstitialis pertains to the longest day of the year. This is in reference to the ability of yellow star thistle to flower very late into the summer. It grows on rangelands, pastures, agricultural areas, along highways or roads, railroad tracks, and other transportation or communication lines. It is dependent on seed production for growth and spread. A distinguishing characteristic is the bracts of the yellow flower heads contain stout, needle-like, straw-colored spines one to two inches long that radiate from the flower head in the shape of a star. The bracts are light green, variably covered in cobwebby hairs and may become smooth.
Prefers well-drained soil of any type and any pH and can grow in nutritionally poor soil as well as very alkaline soils. It can tolerate drought. It cannot grow in the shade. Yellow star thistle has a stout taproot and/or pubescent stems. Root growth during the winter and early spring is rapid and can extend well beyond 3 feet in depth. The stem is erect, slender, hairy and branching, and can grow up to three feet tall.
Sheep, goats or cattle are effective in reducing Yellow Star Thistle seed production when grazed after plants have bolted but before spines form on the plant. Goats will eat Yellow Star Thistle even in the spiny stage. When ingested by horses, it destroys the animal’s ability to chew and swallow and death occurs through starvation or dehydration.
Because of it's weedy nature, it shouldn't have a place in the garden.
Quick ID
- Yellow thistle-like flowers
- Long, sharp spines on the bracts in the shape of a star
- Gray-green hairy foliage and winged stems
Insects, Diseases, and Other Plant Problems: It is considered invasive in many of the western United States and upper mid-West. To manage the plants, in small spaces before bolting, pull the plants by hand and dispose of them.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Cultivars / Varieties:
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Attributes:
- Genus:
- Centaurea
- Species:
- solstitialis
- Family:
- Asteraceae
- Life Cycle:
- Annual
- Recommended Propagation Strategy:
- Seed
- Country Or Region Of Origin:
- Southern Europe and North Africa
- Distribution:
- United States and the southern part of Canada
- Particularly Resistant To (Insects/Diseases/Other Problems):
- Dry soil and poor soil tolerant
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Whole Plant Traits:
- Plant Type:
- Weed
- Wildflower
- Habit/Form:
- Dense
- Erect
- Growth Rate:
- Rapid
- Maintenance:
- High
- Texture:
- Medium
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Soil Texture:
- Clay
- Loam (Silt)
- Sand
- Shallow Rocky
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Occasionally Dry
- USDA Plant Hardiness Zone:
- 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a
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Fruit:
- Fruit Color:
- Cream/Tan
- Display/Harvest Time:
- Fall
- Fruit Type:
- Achene
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- An achene (about a quarter-inch long) finely hairy, straw-colored at maturity with a tuft of short, stiff, light brown bristles at the tip; the seed often remains in the seed-heads until late fall or winter
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Flowers:
- Flower Color:
- Gold/Yellow
- Flower Inflorescence:
- Cyme
- Head
- Flower Bloom Time:
- Fall
- Summer
- Flower Shape:
- Dome
- Flower Petals:
- 7 - 20 petals/rays
- Flower Size:
- < 1 inch
- Flower Description:
- Yellow flowers have bracts armed with stout, needle-like, straw-colored spines one to two inches long that radiate from the flower head in the shape of a star
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Leaves:
- Leaf Color:
- Gray/Silver
- Green
- Leaf Type:
- Compound (Pinnately , Bipinnately, Palmately)
- Leaf Arrangement:
- Alternate
- Rosulate
- Leaf Shape:
- Linear
- Oblong
- Leaf Margin:
- Lobed
- Undulate
- Hairs Present:
- Yes
- Leaf Length:
- 3-6 inches
- Leaf Width:
- < 1 inch
- Leaf Description:
- Leaves are alternate and form a basal rosette up to 6 inches long when young, often lobed in narrow sections on the lower half of the leaf, and tapering to a short stalk. This rosette will wither by the time the plant flowers. All leaves are toothless and covered in woolly hairs giving a gray-green cast. Leaves become much smaller, linear-oblong and undivided as they move further up the stem with the leaf bases extending down the stem, forming “wings”. The wings are often wavy and may be broad with jagged or smooth edges.
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Stem:
- Stem Color:
- Gray/Silver
- Green
- Stem Is Aromatic:
- No
- Stem Form:
- Straight
- Stem Surface:
- Hairy (pubescent)
- Stem Description:
- The stem is erect, slender, hairy and branching, and can grow up to three feet tall
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Landscape:
- Resistance To Challenges:
- Drought
- Problems:
- Problem for Horses
- Spines/Thorns