Youngia japonica

It is an annual that produces yellow flowers. In tropical areas, it can bloom year round, while in temperate areas it blooms in late spring and early summer.[2] Plants are variable in height, ranging from 10 to 150 cm (4 to 59 in) depending on growing conditions. Stems are usually solitary and erect. Basal leaves are large a pinnately divided. Its fruits are wind dispersed.[3]

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  Youngia japonica grows tall under favorable conditions

Youngia japonica is native to eastern Asia in China and Japan.[3][4] However, it has been spread far from its initial range, and is now found as a non-native species nearly worldwide. It is present in Africa, Australia, Europe, North America, and South America.[2] In the United States, it is spreading rapidly, although it is largely restricted to areas in the Southeast.[5][6] It grows well in response to human disturbance, and is found in areas in areas such roadsides, cultivated fields, and in lawns.[2] In China, it is found in a variety of natural and disturbed habitats.[3] It is known to penetrate into intact natural communities as an invasive species in the United States.[5]

Three subspecies are recognized. They are:[3]

• Y. japonica ssp. elstonii - With many stem leaves. Not known to be weedy.
• Y. japonica ssp. japonica - With few to no stem leaves. A weed found nearly worldwide.
• Y. japonica ssp. longiflora - Has larger flowers. Not known to be weedy. This is considered the most distinct subspecies.

It has been reported to form intergeneric hybrids with Lapsanastrum humile in Japan.[4]