False Shrubby Indigo Bush

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Amorpha fruticosa

This is a tremendous shrub that, for whatever reason, has never been spotlighted. It is a native shrub to North America ranging from northern Mexico, United States and into southern Canada. Here is Ontario, it is sadly listed as ‘ Extremely Rare ‘ where only 1 wild population remains. Funny fact – the indigo shrub was introduced into Europe and Asia as an ornamental and is now considered invasive. Sound familiar?

The Latin name describes this bush perfectly. Amorpha fruticosa – Amorpha refers to the Greek name for shapeless and fruticosa is derived from ‘ frutex’ meaning shrubby. Don’t let the name deter you for it is the flowers we are interested in. All I can say is that this shrub is a pollinator magnet when it is blooming. In fact, it is rated by pollination experts as ‘ special value to native bees ‘ where most of the pollination of the false shrubby indigo’s flowers is performed by small to medium sized bees. That is why we started to grow it at the nursery. Also, it is a larval plant to at least 5 caterpillars such as the gray hairstreak and silver spotted skipper.

The flowers are gorgeous when they arrive in June. A rich purple with contrasting yellow pollen. A word of caution. The fragrance of these flowers is not floral, in fact, a bit stinky. Kind of reminds me of pawpaw. The floral show goes for 3 weeks, weather depending. Afterwards, the bush will develop long strings of seeds that songbirds, bobolinks and quail will eat.

Indigo Bush Flower
Indigo Bush Flower

When I started doing more, in depth research on this plant, I realized it is just as important for land restoration as it is for feeding pollinators. A uniquely tough and versatile plant. First, let’s look at its soil builder abilities. Since false shrubby indigo is part of the legume family, it can be grown in nutritionally deficient soils because it has the ability to fix Nitrogen and actually build soil stores. Secondly, its sheer adaptability to growing conditions is remarkable. It can grow from stream and pond edges to gravel bars to open woods and roadsides. This means that Amorpha can be grown on many compromised sites.

In the US, this shrub is being planted out to upland sites to act as a shore stabilizer, soil anchor and control against soil erosion. Why? It has the ability to thicket form. Also, it is wind tolerant and it has very few pests or disease issues. Promising results have been generated where cover has been restored to these damaged areas and food provided enough to see increases in bird populations such as quail and bobwhite.

Being an almost invincible shrub has its down side as a gardener. Please be aware that planting location is everything with this shrub. Place it in an area where it cannot become invasive to its neighboring native plant community. Be sure to contain it. It is definitely worth it.

Some fun facts that I came across. Historically, the Plains native Americans would spread the Amorpha branches on the ground of their bison butchering area to keep the meat clean. Nowadays, very promising work identifying chemical components from shrubby indigo is being done in the fight against diabetes and metabolic syndrome.

Mature Indigo Bush
Mature Indigo Bush

Here is a quick summary of growth requirements for Amorpha fruticosa

Height : 3 – 8 feet in southern Ontario

Height : 3 – 8 feet in southern Ontario

Sun : full to partial sunny

Soil : Does well in wet conditions but adaptable to dry and acidic soils.

Wind tolerant

Deer do not really like it.

Resents root disturbance – plant into its forever home when a small seedling.

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