Origin
Physostigma cylindrospermum (Welw. ex Baker) Holmes, also known as Calabar bean, is a perennial plant native to tropical Africa, particularly in Nigeria, Cameroon, and Ghana. It grows in moist, shaded areas, such as riverbanks and forest undergrowth.
Common Names
Aside from Calabar bean, Physostigma cylindrospermum is also recognized by its numerous common names, including ordeal bean, chop nut, insane root, and esere.
Uses
Calabar bean has been widely used in traditional African medicine in treating a variety of ailments, such as gastric ulcers, skin diseases, and eye infections. However, the plant contains high concentrations of physostigmine, a potent alkaloid that is highly toxic if ingested in large amounts. As a result, the plant is now only used in very small doses for medical purposes, and under careful supervision.
Physostigmine is also used in conventional medicine as a treatment for glaucoma and myasthenia gravis, a neuromuscular disorder characterized by muscle weakness and fatigue.
General Appearance
Physostigma cylindrospermum is a climbing shrub that can reach up to 5 meters in length. The plant has a woody stem with small, pointed leaves that are arranged in pairs. Its flowers are pink, purple, or white, and grow in clusters at the end of branches. The fruit of the plant is a large bean pod that is cylindrical in shape, with a rough, warty exterior. The pods contain as many as 12 brown seeds, which are highly toxic when ingested.
Light Requirements
Physostigma cylindrospermum typically grows best in full to partial sunlight. However, in areas with high temperatures, it is best to provide some shade during the hottest parts of the day to prevent scorching.
Temperature Requirements
The ideal temperature range for Physostigma cylindrospermum is between 20-30°C (68-86°F). Temperatures outside of this range may slow down growth or cause damage to the plant. In colder climates, it is important to protect the plant from frost.
Soil Requirements
Physostigma cylindrospermum prefers well-draining soil that is rich in organic matter. The soil should be slightly acidic with a pH between 5.5-6.5. It is important to avoid soil that is too compact or heavy as this can restrict root growth. Regular watering is important, but the soil should not be allowed to become waterlogged as this may cause root rot.
Cultivation
The plant Physostigma cylindrospermum, also known as Calabar bean, is an annual climbing vine that is native to tropical Africa. This plant requires a warm, humid environment with full sun to partial shade. It can be grown indoors as well as outdoors.
When planting outside, it is best to sow the seeds directly in moist soil, about 1 to 2 inches deep, and at least 3 feet apart to allow for proper growth. The soil should be well-draining and rich in organic matter. The ideal temperature for germination is between 75°F and 85°F.
Watering Needs
Calabar bean requires consistent moisture to grow and thrive. When grown outdoors, it should be watered once a week, or more in extreme heat. Indoors, it should be kept evenly moist, but not waterlogged, by watering whenever the top inch of soil is dry. During the winter months, the plant may require less frequent watering.
Fertilization
It is best to fertilize Calabar bean at the beginning of the growing season with a balanced fertilizer, and then periodically throughout the season. A slow-release fertilizer can also help maintain the plant's growth. If using a liquid fertilizer, it should be diluted to half the recommended strength before application. Over-fertilization can lead to excessive foliage growth and reduced production of the beans.
Pruning
Calabar bean does not require regular pruning. However, it may be necessary to prune back any dead or damaged growth or to control the size of the plant. This can be done at any time of year, but early spring is the best time for major pruning. When pruning, use clean, sharp tools to prevent damage to the plant and avoid spreading diseases.
Propagation of Physostigma cylindrospermum
Physostigma cylindrospermum, also known as calabar bean, is primarily propagated through seed, although vegetative propagation is also possible. Here are the details on each method:
Seed propagation
Seeds of Physostigma cylindrospermum can be sown directly into the ground, or started indoors in pots. The seeds should be soaked in warm water for 24 hours before sowing to soften the seed coat. After sowing, keep the soil moist and warm, ideally around 25-30°C. Germination usually takes 2-4 weeks.
Because the seeds have a hard coat, some gardeners recommend scarifying the seeds either manually or using acid treatment to help with germination. However, correct handling of acid is critical to avoid damage to yourself and the seeds, and should not be performed unless proper safety gear is worn.
Vegetative propagation
While seed propagation is the most common method for Physostigma cylindrospermum, it is also possible to propagate through vegetative means, via cuttings. However, this method has a lower success rate and can be more challenging.
Cuttings should be taken from healthy plants in late spring or early summer and treated with a rooting hormone before planting in well-draining soil. Cover the pot with a plastic bag to maintain high humidity and keep the soil moist until the cutting takes root. It may take several months for rooting to occur.
Overall, seed propagation is the most reliable method for Physostigma cylindrospermum, and with proper care, this plant can grow well both indoors and outdoors.
Disease and Pest Management for Physostigma Cylindrospermum
Physostigma cylindrospermum, commonly known as Calabar bean, is a tropical plant with medicinal properties. However, it is prone to attacks from pests and diseases that can reduce its productivity. Proper pest and disease management is, therefore, essential for plant health and increased yields.
Common Diseases that Affect Physostigma Cylindrospermum
The plant is susceptible to several fungal diseases, including leaf spot, anthracnose, and stem rot. Leaf spot is characterized by the presence of brown or black spots on the leaves. The affected leaves eventually turn yellow and fall off. Anthracnose, on the other hand, causes the stems and leaves to rot, resulting in wilting and death of the plant. Stem rot usually affects the stem base, causing it to rot and turn brown, leading to the death of the plant.
Management of Fungal Diseases
Proper sanitation practices are essential in managing fungal diseases. This involves pruning and removing infected leaves, stems, and branches to prevent the spread of the disease. The use of fungicides is also effective in controlling fungal diseases. Fungicides should be applied at the first sign of infection at intervals recommended by the manufacturer.
Common Pests Affecting Physostigma Cylindrospermum
The plant is also susceptible to pest infestations, with the most common pests being spider mites and aphids. Spider mites are tiny insects that cause discoloration and wilting of leaves. They are usually found on the undersides of leaves, where they feed on the sap from the plant. Aphids, on the other hand, suck sap from the leaves, resulting in stunted growth and curling of leaves.
Management of Pest Infestations
The use of insecticides is an effective way of managing pest infestations. Insecticides should be applied as soon as possible to prevent the spread of infestation. In addition to the use of insecticides, regular inspection of the plant is essential in detecting infestation early. Infected leaves and branches should be pruned and destroyed to prevent the spread of the infestation.
Conclusion
Effective pest and disease control measures are essential in maintaining the health of Physostigma cylindrospermum and ensuring increased yields. Regular monitoring and inspection of the plant will help detect any infestations or diseases early, enabling prompt action. the use of chemicals should be used as a last option with proper instructions from licensed professionals.
