Overview of Otholobium obliquum
Otholobium obliquum (E.Mey.) C.H.Stirt., also known as Oblique-Leaved Psoralea or the obliqueleaf psoralea, is a perennial plant species that belongs to the legume family Fabaceae. The plant is native to Africa, specifically in the countries of Angola, Botswana, Namibia, South Africa, and Zimbabwe.
General Appearance
The Otholobium obliquum plant typically grows up to a height of one meter and has a bushy, spreading habit. It has hairy stems that are reddish-brown in color. The leaves are oblong and have a distinct oblique shape, which means that they are asymmetrical or slanting in relation to the central vein. The leaf color is grayish green on the upper surface and paler green on the underside. The flowers are small, clustered together in spikes, and can be yellow, cream, or white in color.
Common Names
The Otholobium obliquum plant goes by various common names depending on the country or region. In South Africa, it is commonly called the Gousblom, which means "goose flower" in Afrikaans. In Zimbabwe, it is known as the Mashukulumbwi. In Botswana, it is referred to as the Matlahong.
Uses
Traditional healers in southern Africa have long used Otholobium obliquum for its medicinal properties. In particular, the roots and leaves are used to treat conditions such as coughs, diarrhea, and tuberculosis. The plant is also used in the cosmetic industry, with the extracts being used in skin creams and hair care products.
Aside from its medicinal and cosmetic uses, Otholobium obliquum is also useful in the maintenance of ecosystems. The plant serves as a food source for various wildlife, including baboons and antelopes. It is also known to help prevent soil erosion due to its complex root system.
Light Requirements
Otholobium obliquum requires full sunlight exposure to grow optimally. Therefore, it is recommended to plant it in open areas with direct access to sunlight without being obstructed by other large plants. In areas with high temperatures, it can tolerate partial shade to avoid leaf scorching.
Temperature Requirements
Otholobium obliquum grows well in hot temperature conditions. It can tolerate a wide range of temperatures, including extreme heat and cold. However, it grows best in temperatures ranging between 20°C to 30°C. The plant can become dormant during extreme temperatures to conserve water and survive until favorable temperature conditions are met.
Soil Requirements
Otholobium obliquum prefers well-drained soils with a mildly acidic to neutral pH range of 6.0 to 7.0. It thrives well in sandy soils, but it can also adapt well to loamy soils. The soil must be enriched with organic matter and nutrients like phosphorus and potassium. However, the plant is sensitive to heavy-metal toxicities and prefers soils with a low concentration of heavy metals.
Cultivation Methods
Otholobium obliquum is a low growing, perennial plant that can be grown in both full sun and partial shade. The plant is frost tolerant and prefers well-draining soil with a pH range of 6.0 to 7.5. The plant can be propagated from seed or cuttings, and it is recommended to sow the seeds in spring or early autumn. The plant should be planted at a depth where the root ball is level with the soil surface and should be watered regularly until established.
Watering Needs
Otholobium obliquum prefers moist soil but does not tolerate standing water. The plant should be watered deeply once a week, or more often during hot and dry weather. It is important to avoid over-watering, as this can cause root rot and damage the plant. The plant should be watered at its base, as water on the leaves can cause fungal diseases.
Fertilization
Otholobium obliquum does not require heavy fertilization and can grow well with minimal fertilization. However, it can benefit from a light application of balanced fertilizer in the spring to encourage healthy growth. The fertilizer should be applied at the base of the plant and watered in thoroughly. Over-fertilization can cause excessive growth and weaken the plant.
Pruning
Otholobium obliquum does not require heavy pruning but can benefit from the occasional trimming to maintain its shape and encourage bushier growth. The plant can be trimmed in spring, after flowering, by removing any dead or damaged stems and cutting back any overgrown branches. The plant can also be trimmed lightly throughout the growing season to maintain its size and shape.
Propagation of Otholobium obliquum
Otholobium obliquum is a fascinating plant native to the African continent. It is a member of the Fabaceae family and is also known as E.Mey. and C.H.Stirt. There are three primary methods of propagating Otholobium obliquum, namely seed propagation, stem cuttings, and division.
Seed Propagation
Seed propagation is one of the easiest methods of propagating Otholobium obliquum. It involves collecting the seeds and planting them in proper conditions. The best time to plant the seeds is the beginning of spring.
The seeds should be soaked in water for approximately 24 hours before planting. This soaking allows water to penetrate the seed coat and help in the germination process. After soaking, the seeds can be planted in a seed tray or a small pot filled with a well-drained soil mix. The seeds should be planted at a depth of approximately 1 cm and watered thoroughly. Germination should occur within two weeks.
Stem Cuttings
Stem cuttings is another effective propagation method for Otholobium obliquum. New plants can be produced quickly using this method. The best time to take a stem cutting is towards the end of spring or the beginning of summer.
The cutting should be about 6 cm in length and have at least two leaf nodes. The leaves on the lower half of the cutting should be removed so as not to interfere with the rooting process. Dip the cutting in a rooting hormone and put it in a pot with a well-drained soil mix. Keep the soil moist and place the pot in an area with indirect light. After approximately three weeks, new growth should appear, indicating that the cutting has rooted successfully.
Division
Division is a propagation method used for mature Otholobium obliquum plants. This method involves dividing the plant into smaller parts while ensuring that each section has a healthy root system.
To divide, gently remove the entire plant from the soil and separate the root system gently. Be sure to keep several stems attached to each section. The separated sections can then be planted in individual pots or back into the garden bed.
Disease Management
Otholobium obliquum is generally a healthy plant that does not suffer from many diseases. However, under certain conditions, various fungal infections can occur.
Leaf spot: This fungal disease causes irregularly shaped lesions on the leaves with yellowing and premature dropping of leaves. To manage leaf spot, it is essential to remove the infected leaves and treat the plant with a fungicide.
Root rot: This occurs when the soil is too moist and prevents the roots from receiving enough oxygen, leading to the root's death and decay. To manage root rot, ensure that the soil has proper drainage, avoid over-watering, and treat the soil with fungicides.
Pest Management
Otholobium obliquum is also generally pest-free, but some pests can attack the plant.
Aphids: These small insects suck the sap from the plant, stunting growth and causing yellowing of the leaves. To manage them, spray the plant with an insecticidal soap or neem oil.
Spider mites: These tiny pests are difficult to see and can cause yellowing of the leaves and webbing on the plant. To manage them, increase humidity and spray with insecticidal soaps or neem oil.
Caterpillars: Caterpillars can chew through the foliage, causing severe damage to the plant. To manage them, handpick them off the plant or use Bacillus thuringiensis (Bt), a natural insecticide.
Regularly observing the plant for signs of disease and pests and taking proactive measures to address them is essential to maintain the health and beauty of Otholobium obliquum.
