Cirsium
Common Name(s):
- Phonetic Spelling
- SIR-see-um
- This plant is an invasive species in North Carolina
- Description
-
Thistles are in the Asteraceae (daisy) family and can be biennials or short-lived perennials, natives or non-natives. Its name comes from the Greek kersion which means thistle. Some have come from Asia and Europe, and others are native to North America. They all have spines. Two species, Cirsium arvense and C. vulgare are non-native and considered weedy. Thistles vary greatly in their size and the color of the flowers. Some flowers are fragrant, most are not. There are about 60 species that are native to North America.
Some thistles prefer sunny, open areas and some can tolerate some shade. It grows in all types of soils from moist wetlands to mostly dry conditions and in a wide range of pH. They have a central taproot and spread mostly by seeds (one by rhizomes). Most species produce flowers only in their second summer (and every summer thereafter, for perennial species).
Thistles are a high-value nectar plant for bees and butterflies, and songbirds eat the seeds and use the tufts of the seeds for their nests. The seeds are rich in oil, an important food source for seed-eating birds. It is the host plant for the Little Metalmark butterfly (Calephelis virginiensis), which has three to five broods from March-October, and Painted Lady Butterfly (Vanessa cardui) which have one to three flights in the east from May-October, and three to four flights in south Texas from October-April. Flowers are also attractive to hummingbirds. Members of this genus support the following specialized bees: Thistle Long-horned bee Melissodes desponsus, plus Osmia (Helicosmia) chalybea and Osmia (Helicosmia) texana.
Native thistles are a great option in a meadow garden or naturalized area when looking for native host plants for the Little Metalmark butterfly or the Painted Lady butterfly. Select with care, as some native species may spread into areas (such a lawns and flower beds) where they are not wanted. Some gardeners object to their spininess.
Quick ID Hints:
- Very spiny leaves and bracts subtending the heads
- heads like artichokes that bear numerous flowers.
Insects, Diseases, and Other Plant Problems: No significant problems.
- See this plant in the following landscape:
- Cultivars / Varieties:
-
- Tags:
- Cultivars / Varieties:
-
- Tags:
-
-
Attributes:
- Genus:
- Cirsium
- Family:
- Asteraceae
- Life Cycle:
- Biennial
- Perennial
- Recommended Propagation Strategy:
- Seed
- Country Or Region Of Origin:
- Europe, Asia, Africa, Southern America and Northern America
- Distribution:
- From Canada to Florida, coast to coast
- Wildlife Value:
- Members of the genus Cirsium support the following specialized bees: Melissodes (Heliomelissodes) desponsus, Osmia (Helicosmia) chalybea and Osmia (Helicosmia) texana. Birds eat the seeds.
- Particularly Resistant To (Insects/Diseases/Other Problems):
- Deer don't bother them.
- Edibility:
- Has been used for food in some countries.
-
-
Whole Plant Traits:
- Plant Type:
- Herb
- Native Plant
- Weed
- Wildflower
- Woody Plant Leaf Characteristics:
- Deciduous
- Habit/Form:
- Erect
- Growth Rate:
- Medium
- Maintenance:
- Medium
- Texture:
- Coarse
- Appendage:
- Spines
-
-
Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Clay
- Loam (Silt)
- Sand
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Good Drainage
- Occasionally Dry
- Occasionally Wet
- Available Space To Plant:
- 12 inches-3 feet
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
-
-
Fruit:
- Fruit Color:
- Cream/Tan
- Fruit Value To Gardener:
- Showy
- Display/Harvest Time:
- Fall
- Fruit Type:
- Achene
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- Seeds are produced singly in a flat, dark brown fruit about 1/10 of an inch long. Seeds produce a feathery pappus (similar to dandelion ‘seeds’) which help disperse the seeds.
-
-
Flowers:
- Flower Color:
- Gold/Yellow
- Pink
- Purple/Lavender
- Red/Burgundy
- White
- Flower Inflorescence:
- Head
- Flower Value To Gardener:
- Good Cut
- Flower Bloom Time:
- Fall
- Summer
- Flower Shape:
- Dome
- Flower Petals:
- Bracts
- Flower Size:
- 1-3 inches
- Flower Description:
- Numerous disc florets that are divided into 5 long thread-like lobes giving it a showy hair-like appearance. Spines present in the numerous bracts below the flower.
-
-
Leaves:
- Woody Plant Leaf Characteristics:
- Deciduous
- Leaf Color:
- Green
- Leaf Feel:
- Prickly
- Leaf Type:
- Simple
- Leaf Arrangement:
- Alternate
- Rosulate
- Leaf Shape:
- Elliptical
- Oblanceolate
- Leaf Margin:
- Lobed
- Hairs Present:
- Yes
- Leaf Length:
- > 6 inches
- Leaf Width:
- 1-3 inches
- Leaf Description:
- Most have a basal leaf arrangement and alternate stem leaves with pronounced stiff spines along the edges. Natives can be easily identified to have stiff hairs on the upper surface, but softer white hairs below.
-
-
Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Surface:
- Hairy (pubescent)
- Stem Description:
- Green, occasionally finely grooved longitudinally.
-
-
Landscape:
- Landscape Location:
- Meadow
- Naturalized Area
- Landscape Theme:
- Pollinator Garden
- Attracts:
- Butterflies
- Hummingbirds
- Moths
- Pollinators
- Songbirds
- Specialized Bees
- Problems:
- Invasive Species
- Spines/Thorns
- Weedy
