Cirsium ochrocentrum
Encyclopedia
Cirsium ochrocentrum is a species of thistle
known by the common name yellowspine thistle. It is native to the central United States, but its distribution is somewhat wider, reaching to California
and into Mexico
where the plant has been introduced
. It is a weed which grows in disturbed areas such as roadsides. This is a perennial herb growing up to a meter tall with one to twenty white woolly stems per plant. The leaves are generally deeply lobed and the lobes cut into sharp teeth. The longest leaves at the base of the plant are up to about 25 centimeters long. The leaves are spiny, with spines up to 1.5 centimeters long. The inflorescence
produces several flower heads
, each lined with hard, toothed phyllaries
tipped with spines. The head contains white, pink, or lavender flowers. The fruit is an achene
with a brown body nearly a centimeter long topped with a pappus
which may be 3 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 yellowspine thistle. It is native to the central United States, but its distribution is somewhat wider, reaching 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...
and into Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
where the plant has been introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
. It is a weed which grows in disturbed areas such as roadsides. This is a perennial herb growing up to a meter tall with one to twenty white woolly stems per plant. The leaves are generally deeply lobed and the lobes cut into sharp teeth. The longest leaves at the base of the plant are up to about 25 centimeters long. The leaves are spiny, with spines up to 1.5 centimeters 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 several 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 lined with hard, toothed 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...
tipped with spines. The head contains white, pink, or lavender flowers. 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 brown body nearly a centimeter 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...
which may be 3 centimeters long.