Cirsium andrewsii
Encyclopedia
Cirsium andrewsii is an uncommon species of thistle
known by the common name Franciscan thistle. It is endemic to California
, where it is known only from the coastline of the San Francisco Bay Area
from Marin
to San Mateo Counties
. It grows in coastal habitat such as sea bluffs and canyons, and is sometimes found on serpentine soil
s. This native thistle is biennial to perennial, producing an erect, leafy stem which can reach two meters in height. It is highly branched, dense to clumpy, fleshy, and cobwebby with fibers, especially when new.
The leaves are woolly or cobwebby, spiny along the edges, and sometimes lack lobes or deep cuts. They are borne on petioles
with winged, spiny margins, some spines exceeding a centimeter long. The inflorescence
produces one or more flower heads
, each up to 3 centimeters long by 5 wide, wispy with cobwebby fibers, and lined with very spiny phyllaries
. The flower head is packed with dark purplish-pink flowers up to abou 2.5 centimeters in length. The fruit is an achene
with a dark brown body about half a centimeter long and a pappus
about 1.5 centimeters long.
Cirsium
Cirsium is a genus of perennial and biennial flowering plants in the Asteraceae, one of several genera known commonly as thistles. They are more accurately known as Plume thistles. These differ from other thistle genera in having feathered hairs to their achenes...
known by the common name Franciscan thistle. It is endemic to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, where it is known only from the coastline of the San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
from Marin
Marin County, California
Marin County is a county located in the North San Francisco Bay Area of the U.S. state of California, across the Golden Gate Bridge from San Francisco. As of 2010, the population was 252,409. The county seat is San Rafael and the largest employer is the county government. Marin County is well...
to San Mateo Counties
San Mateo County, California
San Mateo County is a county located in the San Francisco Bay Area of the U.S. state of California. It covers most of the San Francisco Peninsula just south of San Francisco, and north of Santa Clara County. San Francisco International Airport is located at the northern end of the county, and...
. It grows in coastal habitat such as sea bluffs and canyons, and is sometimes found on serpentine soil
Serpentine soil
A serpentine soil is derived from ultramafic rocks, in particular serpentinite, a rock formed by the hydration and metamorphic transformation of ultramafic rock from the Earth's mantle....
s. This native thistle is biennial to perennial, producing an erect, leafy stem which can reach two meters in height. It is highly branched, dense to clumpy, fleshy, and cobwebby with fibers, especially when new.
The leaves are woolly or cobwebby, spiny along the edges, and sometimes lack lobes or deep cuts. They are borne on petioles
Petiole (botany)
In botany, the petiole is the stalk attaching the leaf blade to the stem. The petiole usually has the same internal structure as the stem. Outgrowths appearing on each side of the petiole are called stipules. Leaves lacking a petiole are called sessile, or clasping when they partly surround the...
with winged, spiny margins, some spines exceeding a centimeter long. The inflorescence
Inflorescence
An inflorescence is a group or cluster of flowers arranged on a stem that is composed of a main branch or a complicated arrangement of branches. Strictly, it is the part of the shoot of seed plants where flowers are formed and which is accordingly modified...
produces one or more flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
, each up to 3 centimeters long by 5 wide, wispy with cobwebby fibers, and lined with very spiny phyllaries
Bract
In botany, a bract is a modified or specialized leaf, especially one associated with a reproductive structure such as a flower, inflorescence axis, or cone scale. Bracts are often different from foliage leaves. They may be smaller, larger, or of a different color, shape, or texture...
. The flower head is packed with dark purplish-pink flowers up to abou 2.5 centimeters in length. The fruit is an achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
with a dark brown body about half a centimeter long and a pappus
Pappus (flower structure)
The pappus is the modified calyx, the part of an individual disk, ray or ligule floret surrounding the base of the corolla, in flower heads of the plant family Asteraceae. The pappus may be composed of bristles , awns, scales, or may be absent. In some species, the pappus is too small to see...
about 1.5 centimeters long.