Amorpha fruticosa (desert false indigo, "Itachihagi")

Japanese name: イタチハギ （鼬萩）
Scientific name: Amorpha fruticosa

[Overview]
A deciduous shrub usually about 1–3 m tall, sometimes reaching 6 m.
It grows in coastal forests, disturbed riverbanks, bare ground and similar places, and often forms colonies.
The trunk branches freely in the upper part, and first-year branches have ridges.
Leaves are alternate and odd-pinnately compound, 10–30 cm long, with 6–15 pairs of lateral leaflets.
The leaflets are ovate to elliptic and entire.
Three to five racemes, 6–20 cm long, are produced at the branch tips, densely bearing many deep purple flowers.
The flowers are 5–7 mm long; the only petal is the standard, with no wings or keel.
The stamens are longer than the petal, and the yellow anthers are conspicuous.
The fruit is a pod 5–8 mm long, flat and elliptic, with many nectaries raised like warts on the surface.
The pod does not split open when ripe and contains one seed.

[History]
It was first introduced to Japan from Korea in 1912 and was cultivated in gardens as an ornamental.
After World War II, plants brought in for erosion control in mountain forests, prevention of embankment collapse, hedges and cut flowers escaped from cultivation.

[Notes]
It has become naturalized throughout Japan; it is vigorous, tolerates heat and drought, and grows strongly even in poor soil.
While it has been selected as one of "Japan's Worst 100 Invasive Alien Species," it is useful for purposes such as slope greening, and under the Invasive Alien Species Act it is classified as an "alien species for which comprehensive measures are to be pursued separately."

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