Origin
Strychnos polyphylla Gilg & Busse, commonly known as 'Hochstetter's nightshade' or 'snake bean,' is a plant species belonging to the family Loganiaceae. It is native to East Africa, including Tanzania, Kenya, and Uganda, and can be found in dry forests, savannahs, and woodlands at an elevation between 400 and 1,500 meters above sea level.
Common Names
Aside from 'Hochstetter's nightshade' and 'snake bean,' Strychnos polyphylla has various local names depending on the region where it is found. For instance, it is known as 'Mkili' in Tanzania, 'Ichuse' in Kenya, and 'Kiren' in Uganda.
Uses
While Strychnos polyphylla is highly toxic due to its strychnine content, it has various medicinal uses among the local communities in East Africa. It has traditionally been used to relieve body pains and headaches, treat malaria, and even as an aphrodisiac. In addition, the leaves and stem of Strychnos polyphylla are used to repel snakes and are sometimes hung in homes to deter snakes from entering. Apart from medicinal uses, the plant also has some economic importance as the seeds of Strychnos polyphylla are used as a spice, condiment, and coffee substitute in some regions, although they require roasting to remove the toxicity.
General Appearance
Strychnos polyphylla is a perennial shrub or small tree that can grow up to 10 meters tall with a stem diameter of 50 cm. The plant has a dense, rounded crown and a deeply fissured grey bark. The leaves are bright green in color, leathery, and glossy, with a length of up to 15 cm and a width of up to 10 cm. The leaves are shiny and have a waxy texture. The plant produces small, greenish-yellow or white flowers that are sometimes tinged with red or purple. The fruit is a fleshy, elongated capsule that contains numerous seeds enclosed in a bright red aril. The seeds are small, flat, and brown, measuring approximately 5 mm in diameter.
Light Requirements
Strychnos polyphylla requires full sunlight to grow and thrive, making it an ideal plant for open areas with no shading. A minimum of 6 hours of direct sunlight every day is necessary for the growth and development of this plant.
Temperature Requirements
As a tropical plant, Strychnos polyphylla thrives in warm conditions and requires a minimum temperature of 22°C to grow. Optimum growth is achieved at temperatures between 25°C and 30°C, and the plant can tolerate temperatures up to 35°C.
Soil Requirements
The plant prefers well-drained soils that are rich in organic matter. It grows well in sandy or loamy soils with a pH range of 5.5 to 7.5. The soil should be moist but not waterlogged, and waterlogging must be avoided at all costs to prevent root rot and other soil-borne diseases.
Fertilizer Requirements
Strychnos polyphylla requires regular fertilization to promote healthy growth. A balanced fertilizer with equal amounts of nitrogen, phosphorus, and potassium is recommended. The fertilizer should be applied every four to six weeks during the growing season, and the amount should be adjusted according to the age and size of the plant.
Cultivation Methods
Strychnos polyphylla Gilg & Busse is best cultivated through seed propagation. Seeds should be collected from mature fruits and soaked in warm water for 24-48 hours prior to planting. They should be planted in well-draining soil and covered with a thin layer of soil. The planting site should be located in partial shade to protect the seedlings from direct sunlight.
Watering Needs
Strychnos polyphylla Gilg & Busse needs regular watering, especially during the first few months of growth. The soil should be kept moist but not waterlogged. Overwatering can lead to root rot and affect the overall health of the plant. During dry spells, the plant may need to be watered more frequently.
Fertilization
Applying a balanced fertilizer to the soil can help improve the growth rate and overall health of Strychnos polyphylla Gilg & Busse. Fertilizer should be applied during the growing season, which is usually in late spring or early summer. A slow-release fertilizer can be used, or a liquid fertilizer can be added to the soil every two weeks. It is important not to over-fertilize, as this can lead to excessive growth and weaken the plant.
Pruning
Pruning is not necessary for Strychnos polyphylla Gilg & Busse, but if desired, it can be done to shape the plant or maintain its size. Pruning should be done in late winter or early spring before the start of the growing season. Dead or damaged branches can be removed at any time throughout the year.
Propagation of Strychnos polyphylla Gilg & Busse
Strychnos polyphylla is a small, evergreen tree that grows up to 10 m tall. It is native to tropical Africa and is commonly known as the African Ivory Coast Breaktree. This plant is used in traditional medicine and has great economic value.
Propagation Methods
The plant is propagated by seeds, cuttings, or grafting.
Seed Propagation
The seeds are collected from the fruit and should be planted immediately to ensure good germination. The seeds need to be scarified before planting, to break the hard outercoat, which helps the seed to absorb moisture. The seeds can be scarified by soaking them in hot water or by scratching them with a file. The seeds should be sown in a well-draining potting mix, and kept moist until germination occurs, which can take up to 4 weeks. Once the seedlings have developed a few leaves, they can be transplanted into larger containers or planted in the ground.
Cutting Propagation
Cuttings can be taken from mature trees during the rainy season. The cuttings should be approximately 15 cm long and taken from the softwood of the tree. The leaves on the bottom half of the cuttings should be removed and the cutting should be dipped in rooting hormone before being planted in a well-draining potting mix. The cutting should be kept moist and warm, but not in direct sunlight. Rooting can take up to 6 weeks, at which time the cuttings can be transplanted into larger containers or planted in the ground.
Grafting
Another method of propagation is grafting. This is the process of taking a cutting from a mature tree and grafting it onto a rootstock of a related species. The two pieces are joined together, and the tree is allowed to heal. This method is useful for maintaining the characteristics of a particular cultivar in the new plant. Grafting can be done between May and June. Although it is a delicate process, it allows propagation of true-to-type stock with identical traits to the parent tree.
Disease and Pest Management for Strychnos polyphylla Gilg & Busse Plant
Strychnos polyphylla Gilg & Busse, commonly known as the African giant forest tree, is a vital traditional medicinal plant in Africa. It is essential to manage pests and diseases that affect the Strychnos polyphylla plant for improved yield and health. Pest and disease management involve cultural, biological, and chemical control methods.
Common Diseases of Strychnos polyphylla Gilg & Busse
Several factors can contribute to the development of diseases in the Strychnos polyphylla plant, including fungi, bacteria, and viruses. Some of the common diseases that affect the plant include;
- Anthracnose disease: This disease is caused by the Colletotrichum fungus, resulting in leaf spots, premature leaf drop, and fruit rot. The disease can be managed through proper sanitation, removing the affected plant parts, and applying fungicides.
- Root rot: It is a soil-borne disease caused by Phytophthora spp. The disease affects the roots, causing them to rot and eventually leading to plant death. The best way to manage root rot is to avoid over-watering and using well-drained soil.
- Powdery mildew: It is a fungal disease that affects the leaves, causing a powdery coating. The disease can be managed by avoiding overhead irrigation, planting in areas with good air circulation, and removing affected plants.
Common Pests of Strychnos polyphylla Gilg & Busse
The Strychnos polyphylla plant is susceptible to attack by various pests, including insects, rodents, and nematodes. Some of the common pests include;
- Mealybugs: These are sap-feeding insects that infest the plant's leaves. They can be managed by handpicking or spraying insecticides.
- Spider mites: These are tiny arachnids that feed on the plant's sap, causing yellowing and leaf drop. They can be controlled by releasing beneficial insects, such as ladybugs and lacewings, or spraying insecticidal soap.
- Root-knot nematodes: These are soil-dwelling pests that affect the plant's roots, causing stunted growth and yield reduction. They can be managed through crop rotation and soil sterilization.
It is essential to identify and manage pests and diseases early to prevent further spread and damage to the plant. Cultural and biological control methods such as proper sanitation, crop rotation, and beneficial insects are ideal management solutions, but chemical control methods may sometimes be necessary.
