Cirsium brevistylum
Encyclopedia
Cirsium brevistylum is a species of thistle
known by the common names Indian thistle and clustered thistle. It is native to western North America from southwestern British Columbia
to California
, where it grows in moist areas in many types of habitat, from mountain forests to chaparral
and coastal marsh
es. This native thistle is annual or biennial, reaching two meters in height and known to exceed three meters at times. There is usually a single stem which may branch toward the top and is coated in hairs and webby fibers. The leaves are deeply cut into many lobes lined with twisted teeth, the longest leaves near the base of the plant reaching about 25 centimeters long. The leaves are borne on winged petioles
with many spines. The inflorescence
bears one to many flower heads
, both at the ends of the stem branches and in the leaf axils. The flower head reaches about 3 centimeters long by 4 wide and is lined with cobwebby, bristly, spine-tipped phyllaries
. The flower head is packed with white or pink flowers about 2 centimeters long. The fruit is a brown achene
a few millimeters long topped with a pappus
one to two centimeters in length.
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 names Indian thistle and clustered thistle. It is native to western North America from southwestern British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
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 grows in moist areas in many types of habitat, from mountain forests to chaparral
Chaparral
Chaparral is a shrubland or heathland plant community found primarily in the U.S. state of California and in the northern portion of the Baja California peninsula, Mexico...
and coastal marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
es. This native thistle is annual or biennial, reaching two meters in height and known to exceed three meters at times. There is usually a single stem which may branch toward the top and is coated in hairs and webby fibers. The leaves are deeply cut into many lobes lined with twisted teeth, the longest leaves near the base of the plant reaching about 25 centimeters long. The leaves are borne on winged 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 many spines. 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...
bears one to many flower heads
Head (botany)
The capitulum is considered the most derived form of inflorescence. Flower heads found outside Asteraceae show lesser degrees of specialization....
, both at the ends of the stem branches and in the leaf axils. The flower head reaches about 3 centimeters long by 4 wide and is lined with cobwebby, bristly, spine-tipped 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 white or pink flowers about 2 centimeters long. The fruit is a brown achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
a few millimeters long topped with 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...
one to two centimeters in length.