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Description
Cirsium Occidentale Var. Californicum, commonly known as California thistle, is a species of thistle native to California, USA. It belongs to the family Asteraceae and is a highly invasive plant species that can grow up to 6 feet tall. The plant has a taproot system and produces numerous stems that are highly branched. The leaves are alternate, deeply lobed, and spiny. The flowers are purple-pink and appear in clusters at the top of the stem.
Taxonomic Information
| Domain | Eukarya |
|---|---|
| Kingdom | Plantae |
| Phylum | Tracheophyta |
| Class | Magnoliopsida |
| Order | Asterales |
| Family | Asteraceae |
| Genus | Cirsium |
| Species | Occidentale |
| Variety | Californicum |
Appearance
The California thistle has a highly branched stem that can reach up to 6 feet in height. The stem and leaves are covered in spines that can be up to 2 inches long. The leaves are deeply lobed and have a green-grey color. The flowers are purple-pink and appear in clusters at the top of the stem. The plant produces a large number of seeds that are dispersed by wind and animals.
Care Guide
California thistles are highly invasive and can easily take over a garden or landscape. Therefore, it is important to take proper care of them to prevent their spread. Here are some tips:
- Water: California thistles do not need much water and can tolerate drought conditions. Water only when the soil is dry.
- Fertilization: These plants do not need much fertilization. Fertilize once a year with a balanced fertilizer.
- Soil: California thistles can grow in a variety of soils, but prefer well-draining soil. They can tolerate poor soil conditions.
- Sunlight: These plants prefer full sun but can tolerate some shade.
- Hardiness Zones: California thistles are hardy in USDA zones 7 to 10.
Common Pests & Diseases
California thistles are generally not affected by pests and diseases. However, they can be susceptible to aphids, spider mites, and powdery mildew. These can be treated with insecticidal soap or horticultural oil.
Habitat
California thistles are native to California and can be found in a variety of habitats, including grasslands, meadows, and open woodlands. They prefer dry, well-draining soil and can tolerate drought conditions.
Question and Answer
Q: Is the California thistle toxic to animals?
A: No, the California thistle is not toxic to animals.
Q: Can California thistles be used for medicinal purposes?
A: Yes, the California thistle has been used in traditional medicine to treat various ailments, including liver problems and digestive issues.
Q: How can I control the spread of California thistles?
A: California thistles are highly invasive and can easily spread. It is important to remove them as soon as they are spotted and to prevent them from going to seed. They can also be controlled with herbicides, but this should be done carefully to avoid harming other plants.
Q: Can California thistles be grown in containers?
A: Yes, California thistles can be grown in containers, but they will require regular maintenance to prevent them from spreading.
Related Plants
- Cirsium arvense
- Cirsium vulgare
- Cirsium discolor
- Cirsium altissimum
References
- “Cirsium Occidentale.” Calflora, www.calflora.org/cgi-bin/species_query.cgi?where-calrecnum=2312.
- “Cirsium Occidentale.” USDA Plants Database, plants.usda.gov/core/profile?symbol=CIROO.
- “Invasive Weeds: California Thistle.” University of California Agriculture & Natural Resources, ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26394.
