Parks Institute Stage 1 Fire Restrictions June 1, 2013
Due to high fire danger, Sequoia & Kings Canyon National Parks are instituting fire restrictions inside the parks. More »
Road Construction Delays (if Entering/Exiting Hwy. 198)
Expect minimal construction delays on main road through parks (Generals Hwy) through June 2013 on weekdays generally from 7 a.m.-6 p.m. See link for schedule. Call for 24-hour road conditions info: 559-565-3341 (press 1, 1, 1). More »
Vehicle Length Limits Have Changed in Sequoia NP (if Entering/Exiting Hwy 198)
Planning to see the "Big Trees" in Sequoia National Park? If you enter/exit via Hwy. 198, please pay close attention to new vehicle length advisories for your safety and the safety of others. More »
Some Opening/Closing Dates for Services and Facilities May Change – Check Back for Updates
Some opening/closing dates for facilities and visitor services in the parks may change due to weather or other circumstances. Call 559-565-3341 or send us an email using the "Contact Us" link below the main menu (bottom left, this page).
You May Have Trouble Calling Us. Use the "Contact Us" Link (Bottom Left) to Send an E-mail.
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Bull thistle (Cirsium vulgare) is a biennial thistle that grows sporadically at middle elevations of Sequoia and Kings Canyon National Parks. It is native to Europe, and has naturalized throughout many areas of North America; its presence has been recorded in all of the 48 lower states.
Bull thistle is one of the more frequently encountered non-native plants in the parks above 1,400 meters (4,500 feet). Its ability to thrive at higher elevations and in relatively undisturbed areas makes it a species of concern. Currently, it is most common in and around disturbed areas.
This robust thistle is distinctive because of its purple flowers and rough bristly leaves. It is most common in moist disturbed areas. The first year following germination, the plant appears as a rosette of rough, spiny leaves. During the subsequent year, the plant bolts and produces spiny heads of purple flowers that produce abundant seeds. Each plant can produce more than one head. The bell-shaped heads are commonly 3-4 centimeters (1.2-1.6 inches) in diameter. The plant dies after it has produced seeds in the second year.
Photo by Brother Alfred Brousseau, St. Mary's College.
There are native thistle species that could be confused with bull thistle. The surfaces of leaves on bull thistle are rough to the touch, while the surface of the native thistles that occur in Sequoia and Kings Canyon National Parks tend to be smooth. The stems of bull thistle have obvious spiny wings. The native species tend not to have such distinct wings along the stem.
Bull thistle reproduces entirely by seed. A healthy plant can produce up to 5,000 wind-dispersed seeds. The seeds, however, do not remain viable in soil for long periods.
The most extensive infestation of bull thistle in the parks appears to be in and around the Grant Grove area. There are also populations in some areas of the park wilderness. Sequoia & Kings Canyon Natural Resource Management personnel have been actively controlling populations of bull thistle in the Grant Grove area since 1999.
Did You Know?
The mid-elevation Sierra coniferous forest supports a remarkable diversity of tree species. Here ponderosa pine, incense-cedar, white fir, sugar pine, and scattered groves of giant sequoia intermix, forming one of the most extensive stands of old-growth coniferous forest remaining in the world. More...