Japanese name: オオハンゴンソウ（大反魂草） Scientific name:Rudbeckia laciniata
[Overview]
A perennial 0.5–3 m tall, growing in colonies in moist grasslands and on riverbanks.
It has creeping underground stems.
The stem is branched, and hairless or sparsely hairy.
There are basal leaves and stem leaves.
The basal leaves are deeply twice pinnately divided, densely hairy when young, with long petioles.
The stem leaves are alternate, pinnately divided into 5–7 lobes, with the lobes further divided to about the middle, and have long petioles.
On the upper part of the stem the leaves are 3–5-lobed or simple, and sessile.
Both surfaces of the stem leaves are sparsely covered with short hairs.
Flower heads 5–6 cm across are borne facing upward at the stem tips.
There are 6–14 ray flowers, yellow.
The tubular flowers are greenish yellow.
The receptacle is hemispherical, and rises into a cone shape after flowering.
The fruit is an achene.
[History]
It was introduced as an ornamental in the mid-Meiji period.
[Notes]
It is designated a "Specified Invasive Alien Species" under the Invasive Alien Species Act.
