''Senecio aronicoides'' is a species of flowering plant in the
aster family known by the common name rayless ragwort. It is native to
Oregon
Oregon () is a U.S. state, state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington (state), Washington, while the Snake River delineates much of it ...
and northern and central
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
, where it can be found in the woodlands and forests of mountains and foothills, often in relatively dry habitat. It is a biennial or perennial herb growing up to about 90 centimeters tall from a fleshy root attached to a buttonlike
caudex
A caudex (plural: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695
In the strict sense of the term, meaning a stem, "caudex" is m ...
. The plant is often slightly woolly or cobwebby in texture. The leaves have lance-shaped to oval blades measuring up to 20 centimeters long, the largest ones lower on the stem. The
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. Morphologically, it is the modified part of the shoot of seed plants where flowers are formed o ...
is a
corymb which is flat and spreading, often resembling an
umbel
In botany, an umbel is an inflorescence that consists of a number of short flower stalks (called pedicels) that spread from a common point, somewhat like umbrella ribs. The word was coined in botanical usage in the 1590s, from Latin ''umbella'' "p ...
. The
flower heads are cups lined with black- or green-tipped
phyllaries and filled with many gold disc florets. There are usually no ray florets but one or two occasionally emerge from a head. The fruit is a hairless
achene
An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...
tipped with a
pappus of long, white bristles.
External links
Jepson Manual TreatmentUSDA Plants ProfileFlora of North AmericaPhoto gallery
aronicoides
Flora of Oregon
Flora of California
Flora of Northern America
Flora without expected TNC conservation status
{{Senecioneae-stub