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Calabar Bean

A climbing vine indigenous to Africa’s tropical regions used by the tribes to recognize people possessed with evil spirits! Read on to know all the essential information about the Calabar bean plant, its uses, and how to grow it.

About Calabar Bean Plant

Before getting to know the plant’s uses and importance, we need to understand what a Calabar Bean[1] is? Scientifically known as Physostigma venenosum, it is a leguminous, herbaceous plant that is perennial.

The seeds of this plant are poisonous to humans. The Bean is named after its place of origin around Nigeria that was earlier called Calabar.

The old tribes of the Calabar region used it as an ordeal poison on the people impeached for sorcery. It was believed to affect only the guilty.

The beans contain a chemical called physostigmine, which hinders or slows the communication amid nerves and muscles, thereby affecting the Nervous system.

The plant is said to have a variety of uses which makes it an important one. It was first sighted at Edinburg Botanical Gardens when it was planted in the year 1846.

If you are wondering how does it looks like? It has a beautiful appearance! This plant can grow up to 15 meters (50 feet) in height and has a woody stem base with a diameter of around five cm.

It grows bright purple-colored flowers with rich veins and trifoliate leaves that hang down beautifully from the plant.

The beans can grow up to 15-18 cm in size, and they have a thick, hard shell. The bean pods, in turn, consist of 2-3 chocolaty- brown colored seeds each.

Growing Calabar Beans

Although these plants are native to Africa’s western tropical regions and are primarily found in the wilds of wet and dry rain forests, marshes, and even in seasonally flooded forests, You can easily grow and cultivate Calabar Bean plants anywhere by creating an atmosphere suitable for them to flourish.

Let us discuss the essential requirements for growing these beautiful plants at farms or in your home gardens.

The first and foremost requirement for doing that is acquiring good quality seeds, which can be easily found in any seed store or plants themselves.

It is best to propagate them with seeds. You can quickly propagate the seeds directly into the prepared field/ pot, or you can grow them into saplings indoors before transplanting them.

It is best to sow the seeds when they are fully mature and ripe. Always use well-draining soil to grow the Calabar Bean Plant; although they can grow well in various soils, it is best to use soils like sandy-loam, alluvial or black soil.

Any sol you choose to grow, your plants should be rich in nutrients as these plants are heavy feeders and require a lot of nutrition.

When growing in a pot, make sure to use big and wide enough so your plant gets enough space to grow and has a drainage hole to drain off the excess water.

It is also essential that you plant the seeds in a sunny spot or place your pot in such a spot. You must choose a spot that receives plenty of sunlight throughout the day as these plants prosper well in full Sun.

Moreover, these evergreen climbers are native to regions with hot climates, but they have been naturalized in countries like India and Brazil.

So, they can grow in a variety of climatic conditions. The minimum temperature required by these plants to say healthy is around 15- 18 degrees C.

Apart from these requirements, your plants also need constant nurturing and irrigation. Water your plants well keep them hydrated, as lack of water can result in the drying and yellowing of your plant.

You can also mix manure with your soil when you plant your trees to provide them with extra nutrients for better growth.

Uses of Calabar Plants

Despite having poisonous seeds [2] that are non-suitable for consumption, the Calabar plant is said to have many uses in medicine.

The Calabar Plant seeds contain an alkaloid called physostigmine, which is used to treat various eye problems like glaucoma etc.

It is extracted from the seeds and used in many eyedrops to lower the pressure on the eyeballs as their main constituents for treating retinitis, irritable granular lids, prolapsus, and photophobia.

It also works as a laxative herb and slows down the central nervous system, thus used as a depressant for epilepsy, anxiety, and cholera.

Although not proven scientifically, the herb is also said to be effective in emphysema, asthma and reducing memory loss in Alzheimer’s disease,

It also works as a stimulant for Intestinal muscles in the treatment of chronic constipation, post-operative constipation.

The herb is also effective and used as an internal medication in the treatment of various neuromuscular diseases.


Although an important medicinal herb, the plant is still poisonous, and consuming a large amount of it can hurt your health.

To avoid that from happening, certain precautions need to be taken when consuming the herb. Firstly, do not ever consume the herb without consulting your doctor.

There is only a certain amount of dose is prescribed for every age group.

Excessive use can cause problems like It can cause excessive sweating and saliva, diarrhea, irregular heartbeats, convulsions, paralysis, coma, respiratory failures, weak muscles, or even cardiac arrest.

You can avoid the consumption if you are a heart patient, pregnant, feeding mother, intestinal blockage.

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Other Details:

Scientific Name: Physostigma venenosum

Also Known as Calabar bean, Essere (Efik language), ordeal bean

Parts used: Seeds, also known as “beans”

Native to: West Africa, especially southeastern Nigeria

Some Traditional Uses: glaucoma; myasthenia gravis; acute tetanus; played a part in the development of synthetic sex hormones such as those used in the birth control pill

Current Medicinal Uses and Purposes: The synthetic Alzheimers Disease drug Exelon is based on the physostigmine molecule and actions. Pyridostigmine and neostigmine, both used in the treatment of myasthenia gravis, are “cousins” of physostigmine.

Side Effects and Contraindications: Poisonous

Areas of Further Research: Alzheimers Disease