Helenium amarum
Encyclopedia
Helenium amarum is a species of annual herb in the daisy family
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 names yellowdicks, yellow sneezeweed, and bitter sneezeweed. It is native to much of the southeastern United States and northern Mexico, and it is present elsewhere in North America as an introduced species
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...

. This is a multibranched bushy erect plant reaching 20 to 70 centimeters in height and thickly foliated in narrow to threadlike leaves. The tops of stem branches hold 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...

s of many daisylike 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 head has a rounded center of golden yellow disc florets and a fringe of usually lighter yellow ray florets which are reflexed away from the center. The fruit is a tiny achene
Achene
An achene is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate and indehiscent...

 about a millimeter long. This herb is weedy in some areas. The plant is somewhat toxic to mammals and insects due to the presence of the lactone
Lactone
In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...

 tenulin.

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