Japanese name: オオアワダチソウ（大泡立草） Scientific name:Solidago gigantea subsp. serotina
[Overview]
A perennial 0.5–1.8 m tall, found on sunny roadsides, riverbanks and vacant lots.
It spreads well by extending underground stems.
The stems and leaves are almost hairless and not rough to the touch.
The leaves are simple and alternate, linear-lanceolate, 10–15 cm long and 1.5–2 cm wide, with teeth on the upper half.
They have short leaf stalks.
On the upper side of the branches, yellow flower heads about 6–7 mm across are densely arranged, forming a large conical inflorescence overall.
The inflorescence has fewer branches than Seitaka-awadachiso.
Both the ray flowers and the tubular flowers are yellow.
There are 9–14 ray flowers per flower head, and the ray portion is broad.
The fruit is an achene with a pappus.
[History]
It was introduced as an ornamental in the middle of the Meiji era.
[Notes]
It is designated as an Alien Species Requiring Caution under the Invasive Alien Species Act.
It is also listed among Japan's 100 Worst Invasive Alien Species.
