The wide range of the Indigobush is displayed in the fact that the seeds of this originally American shrub have come to Mustila from Northeast China. It has been widely used there and in other suitable locations as a windbreak, to fix Nitrogen or to prevent erosion. The Indigobush tolerates nutritionally poor sites as it grows an extensive root system and has a symbiotic relationship with soil bacteria that fix atmospheric nitrogen. In extreme cases it has become naturalised into an invasive non-native garden escape.
The Indigobush becomes quite tall on a favourable site. Its leaves resemble those of Siberian peashrub (Caragana arborescens), but the leaves are significantly larger. The inflorescences are long and narrow racemes, deep purple with yellow highlights. The genus name Amorpha means deformed and alludes to the corolla which, unlike the typical pea flowers of the family, is formed of a single tubular violet-purple petal. The stamens emerge from the centre, their yellow anthers providing a contrast for the petals. The blossoming Indigobush emits a vanilla perfume in July.
In Mustila, Indigobushes have been planted in the Terassi (Terrace) and at the top of Atsalearinne (Azalea slope). They are not fully winter hardy in the Mustila climate and the tops get frostbitten during most winters. They sometimes manage to blossom, but seeds do not reach maturity.