Holocarpha heermannii
Encyclopedia
Holocarpha heermannii is a species of flowering plant in the aster family
known by the common name Heermann's tarweed.
is a spreading array of branches bearing clusters of flower heads
. Each flower head is lined with phyllaries
which are coated in large bulbous resin glands. They are hairy and sticky in texture. The head contains many yellow disc florets surrounded by three to 10 golden yellow ray florets. The ray and fertile disc florets produce achene
s of different shapes.
, where it grows in the hills, mountains, and valleys of the central part of the state. It is most common in the eastern San Francisco Bay Area
and the southern end of the Sierra Nevada foothills.
Asteraceae
The Asteraceae or Compositae , is an exceedingly large and widespread family of vascular plants. The group has more than 22,750 currently accepted species, spread across 1620 genera and 12 subfamilies...
known by the common name Heermann's tarweed.
Description
Holocarpha heermannii is an annual herb growing mostly erect from 20 centimeters to over one meter in height. The stem is densely glandular and coated in short and long hairs. The leaves are up to 10 centimeters long near the base of the plant and those along the stem are smaller. The inflorescenceInflorescence
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...
is a spreading array of branches bearing clusters of 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 flower head is lined with 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...
which are coated in large bulbous resin glands. They are hairy and sticky in texture. The head contains many yellow disc florets surrounded by three to 10 golden yellow ray florets. The ray and fertile disc florets produce achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...
s of different shapes.
Distribution
Holocarpha heermannii is endemic to CaliforniaCalifornia
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 the hills, mountains, and valleys of the central part of the state. It is most common in the eastern 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...
and the southern end of the Sierra Nevada foothills.