For kids from fourth grade up.
Endangered. This means that we are afraid the species may become extinct.
Suisun thistle is in the aster family. It grows 1 to 2 meters tall. (About 3 to 6 feet tall.) You have probably eaten a different kind of thistle - the artichoke. Can you see how they look alike?
Leaves at the base of the plant are large. They may be 90 centimeters long. (About 35 inches.) Upper leaves are short and narrow. Both have sharp spikes. See photos in sidebar. The ruler in two of the photos measures in centimeters.
Suisun thistle grows in tidal marshes. These are marshes where the water flow is affected by the ocean. It grows in the part of the marshes farthest from the ocean. It is found near the smallest branches of small creeks, banks, ditches and marsh edges.
Plants generally live two years but sometimes longer. They flower the second year, between July and September. Scientists are not sure how they are pollinated. They think it is by bees.
Angelo Garcia, Jr., Dept. of Water Resources
Suisun thistle was once widespread in Suisun Marsh. In the last 20 years has been found in only four places: Grizzly Island, Peytonia Slough, Rush Ranch and Hill Slough.
Suisun thistle used to be very common. Why is it so rare now? It is because most of Suisun Marsh has been diked. So it is not tidal any more.
Invasive plants have also hurt Suisun thistle. Also, wild hogs cause some damage.
Visit Rush Ranch, 2,070 acres of open
space. It includes about 950 acres of undiked brackish tidal marsh. This area provides one of the few remaining homes for Suisun thistle.
Words to Learn
Botanists call Suisun thistle Cirsium hydrophilum var. hydrophilum.Scientific names are in Latin or Greek. The var. means that this is one variety of Suisun thistle.
Suisun thistle is in the Asteraceae (aster) family. This very large family of plants includes asters, daisies and sunflowers besides thistles.
Perennial: A perennial plant or simply perennial is one that lives for more than two years.
Salinity: the amount of mineral salts dissolved in water. Saline - salty water.