Overview of Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is a flowering plant that belongs to the family Rubiaceae. It is native to tropical regions of Africa, including Ethiopia, Kenya, Tanzania, and Uganda. The plant is also known by various common names, such as Johnston’s Hedyotis, Erect Hedyotis, and Swahili Catholic
Appearance of Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is a small, slender herb that typically grows up to 1m tall. The leaves of the plant are oblong or elliptic, with a size of 3–12 cm long and 1–4 cm wide. The leaves are arranged opposite each other on the stem, and they are dark green or nearly black in color. The flowers of Oldenlandia johnstonii are white or pink, and they grow in clusters at the tips of the stem. The fruit of the plant is a capsule that is approximately 4–6mm long.
Uses of Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is commonly used in traditional medicine in East Africa to treat various ailments, such as diarrhea, fever, and headaches. The leaves and roots of the plant are boiled to make a medicinal tea, which is consumed as a remedy for various illnesses. The plant has also been studied for its potential anti-cancer properties, as it contains various bioactive compounds that are believed to inhibit the growth of cancer cells.
Growth Conditions for Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii
Light Requirement: Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is a shade-loving plant and prefers partial shade to full shade. It cannot tolerate direct sunlight and requires a shaded environment to grow well. In its natural habitat, it usually grows under the shade of trees or in the understory of forests.
Temperature Requirement: Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii grows well in warm and humid conditions. It cannot tolerate frost or cold temperatures and prefers warm temperatures year-round. The ideal temperature range for the plant is between 20°C to 30°C.
Soil Requirement: The plant prefers well-drained soil that is moist but not waterlogged. It can grow in a wide range of soil types, including sandy to clayey soils. However, it does best in nutrient-rich soils that are slightly acidic. The pH of the soil should be between 5 to 6.5.
Water Requirement: Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii requires moderate watering. Overwatering can damage the roots as the plant cannot tolerate waterlogged soil. The soil should be allowed to dry slightly between waterings.
Humidity Requirement: Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii prefers a humid environment and requires moderate to high humidity to grow well. It can tolerate low humidity to some extent, but low humidity can cause the plant to wilt and become stunted.
Cultivation methods
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is a perennial plant that thrives in warm and humid conditions. It is best grown in well-draining soils with a pH of 5.5 to 6.5. The plant can be propagated through seeding or cuttings. Seeding should be done in the early spring, while cuttings should be taken from mature plants in late summer or early fall. The recommended planting distance between plants is 15 to 20 cm.
Watering needs
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii requires regular watering to maintain healthy growth and development. The plant prefers moist but not waterlogged soil. Watering should be done early in the morning or late in the evening to avoid evaporation. During the hot and dry season, the plant will require more frequent watering. Overwatering should be avoided as it can lead to root rot and other plant diseases.
Fertilization
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii benefits from regular fertilization to increase plant growth and overall health. A balanced fertilizer with an N-P-K ratio of 10-10-10 is recommended. Fertilizers should be applied every six weeks during the growing season. Care should be taken not to over-fertilize as this can lead to reduced plant growth and development.
Pruning
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii requires pruning to remove dead or damaged leaves and encourage new growth. Pruning should be done in the early spring or late fall when the plant is dormant. It is recommended to remove up to a third of the plant's height during pruning. This will help to promote lush growth and maintain the plant's shape. If the plant is overgrown, selective pruning can be done throughout the growing season to remove older growth and promote new shoots.
Propagation of Oldenlandia johnstonii
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is commonly propagated through seeds and stem cuttings.
Propagation through Seeds
The collection of seeds from mature fruits of Oldenlandia johnstonii is done when the fruit capsules turn brown and start to split open. These seeds are then air-dried under shade for a while before sowing.
The ideal time for sowing Oldenlandia johnstonii seeds is during the rainy season. The seeds can be sown directly in the field or in nursery beds at a depth of about 1 cm. Germination of the seeds usually starts within 7-14 days after sowing. The plants can be transplanted to their permanent location after 4-6 months.
Propagation through Stem Cuttings
Propagation of Oldenlandia johnstonii through stem cuttings is another common method. This is done during the rainy season or in areas with high humidity.
The stem cuttings of 10-15 cm length are taken from healthy and disease-free plants. These cuttings are then dipped in rooting hormones for 24 hours before planting in nursery beds or pots containing a mixture of sand and soil in the ratio of 1:1. The cuttings are then kept in a shaded area and watered regularly.
The cuttings will develop roots within 2-3 weeks and can be transplanted to their permanent location after 4-6 months.
Disease and Pest Management for Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii
Oldenlandia johnstonii (Oliv.) Engl. subsp. johnstonii is a hardy and resilient plant, resistant to many diseases and pests. However, in some specific conditions, the plant may face some issues that may require immediate attention. Here are some of the common diseases and pests that may affect the plant and ways to manage them.
Diseases
Fungal diseases such as rust and powdery mildew are the most common diseases that affect Oldenlandia johnstonii. Rust appears on the leaves as rusty brown spots that spread rapidly, while powdery mildew appears as a powdery white substance on the surfaces of leaves, stems, and flowers. To manage these diseases, regularly inspect the plants and remove infected leaves and flowers. Avoid wetting the leaves during watering. In severe cases, use fungicides such as neem oil to control the spread of the diseases.
Another disease that affects Oldenlandia johnstonii is root rot, which is caused by waterlogged soil and poor drainage. This disease causes the roots to decay, leading to the plant's death. To manage this disease, avoid overwatering the plant and provide good drainage. Transplant infected plants to new, well-draining soil, and avoid reusing the infected soil.
Pests
Oldenlandia johnstonii is usually resistant to many pests, but some pests can still attack the plant, such as mealybugs, spider mites, and aphids. These pests suck the sap from the plant, leading to stunted growth, yellowing of leaves, and leaf drop. To manage these pests, apply insecticidal soap or neem oil to the plant, or use a strong jet of water to wash off the pests. Avoid using pesticides that may harm beneficial insects and pollinators.
Overall, proper care and maintenance of Oldenlandia johnstonii can prevent most diseases and pests. Regularly inspect the plant for any signs of damage, provide adequate light and water, and ensure good soil drainage.
