Canada Thistle
Place of Origin: Europe/North Asia
Place of Harm: Entire north, entire west, Alaska
First Introduced: 1600’s
Harms: Native flowers, grass, and shrubs
Other Names: Californian thistle, creeping thistle, field thistle, corn thistle, perennial thistle
Taxonomy: Asterales, Asteraceae
Canada thistle is a dioecious perennial that was introduced in an accidental seed shipment. They typically grow in roadside ditches, pastures, abandoned areas and gardens. One plant can take over an area 3-6 feet in diameter in 1 year. It grows in a variety of soils and can tolerate up to 2% salt content. It grows best in deep, well-aerated, productive, cool soils. It is found in 17-35 in. annual precipitation zones or where soil moisture is adequate. It is less common in light, dry soils. In shaded areas, plants are tall and drooped, and produce few flowers. It has deep roots that spread over large areas horizontally and vertically. Canada thistle crowds out the native plants, and is one of the worst and most widespread threats in US gardens, due to fast germination and seeding. Another problem is the taking over of crop fields; cattle will not graze near infestations. It is very hard to kill off due to regenerative roots. Horizontal roots may extend 15 feet or more and vertical roots may grow 6 to 15 feet deep. You cannot pull them out effectively, only the seedlings. An at-home way is to cut off the flowers. Persistently cutting is a good idea, but mowing can further spread the seeds. The key to getting rid of Canada thistle is to stress out all of its nutrient reserves. This can be done by continuing to cut it, pull it and bother it. An herbicide such as glyphosate may be used on populations without other plant/animal life. Canada thistle is eaten by goats, cattle, and sheep. Fire can also get rid of it. Canada thistle is spread by wind, birds, or vegetative root growth. In mid-to-late spring, the buds emerge again as rosettes. The serrated leaves have small spikes on them for defense. They are weak during germination, but after 7 to 8 weeks they are able to regenerate. They start to flower in late spring (April), then seed. Each flower can have 1000-1500 seeds, which stay viable for up to 20 years. Similar native species include the Carolina thistle (Cirsium carolinianum). The roots, stalks, and leaves are edible. The pappus (seed tuft) is used by Native Americans as arrow fletch. Cirsium is from Greek kirsos meaning 'swollen vein'. Thistles were used as a remedy against swollen veins. It is found in the Great Smoky Mountains National Park and Blue Ridge Parkway. Northampton, Ashe, Avery, Mitchell, Yancey, Haywood, Jackson, Swain, Clay, Transylvania.
Place of Origin: Europe/North Asia
Place of Harm: Entire north, entire west, Alaska
First Introduced: 1600’s
Harms: Native flowers, grass, and shrubs
Other Names: Californian thistle, creeping thistle, field thistle, corn thistle, perennial thistle
Taxonomy: Asterales, Asteraceae
Canada thistle is a dioecious perennial that was introduced in an accidental seed shipment. They typically grow in roadside ditches, pastures, abandoned areas and gardens. One plant can take over an area 3-6 feet in diameter in 1 year. It grows in a variety of soils and can tolerate up to 2% salt content. It grows best in deep, well-aerated, productive, cool soils. It is found in 17-35 in. annual precipitation zones or where soil moisture is adequate. It is less common in light, dry soils. In shaded areas, plants are tall and drooped, and produce few flowers. It has deep roots that spread over large areas horizontally and vertically. Canada thistle crowds out the native plants, and is one of the worst and most widespread threats in US gardens, due to fast germination and seeding. Another problem is the taking over of crop fields; cattle will not graze near infestations. It is very hard to kill off due to regenerative roots. Horizontal roots may extend 15 feet or more and vertical roots may grow 6 to 15 feet deep. You cannot pull them out effectively, only the seedlings. An at-home way is to cut off the flowers. Persistently cutting is a good idea, but mowing can further spread the seeds. The key to getting rid of Canada thistle is to stress out all of its nutrient reserves. This can be done by continuing to cut it, pull it and bother it. An herbicide such as glyphosate may be used on populations without other plant/animal life. Canada thistle is eaten by goats, cattle, and sheep. Fire can also get rid of it. Canada thistle is spread by wind, birds, or vegetative root growth. In mid-to-late spring, the buds emerge again as rosettes. The serrated leaves have small spikes on them for defense. They are weak during germination, but after 7 to 8 weeks they are able to regenerate. They start to flower in late spring (April), then seed. Each flower can have 1000-1500 seeds, which stay viable for up to 20 years. Similar native species include the Carolina thistle (Cirsium carolinianum). The roots, stalks, and leaves are edible. The pappus (seed tuft) is used by Native Americans as arrow fletch. Cirsium is from Greek kirsos meaning 'swollen vein'. Thistles were used as a remedy against swollen veins. It is found in the Great Smoky Mountains National Park and Blue Ridge Parkway. Northampton, Ashe, Avery, Mitchell, Yancey, Haywood, Jackson, Swain, Clay, Transylvania.
Essential Question
"Could a genetically engineered invasive species potentially be used in warfare?"