Description of Senecio johnstonii Oliv. subsp. cheranganiensis (Cotton & Blakelock) Mabb.
Senecio johnstonii Oliv. subsp. cheranganiensis (Cotton & Blakelock) Mabb. is a plant that belongs to the family Asteraceae and is indigenous to Cherangani Hills in Kenya. It is commonly known as Johnston's groundsel, Cherangani groundsel, or simply groundsel.
General Appearance
Johnston's groundsel is a perennial plant that grows up to 1 meter in height. It has green, hairy leaves, and a woody stem that produces yellow flowers. The plant blooms in the months of February to October.
Uses
The plant has been traditionally used by the Kalenjin people of Kenya for medicinal purposes. They boil the leaves and stems, and then drink the resulting infusion to treat stomach ailments, respiratory problems, and body aches. The plant also has potential uses in the pharmaceutical industry as it contains compounds that have been found to exhibit antitumor activity.
In addition to its medicinal value, Johnston's groundsel is used for ornamental purposes in gardens and landscaping in some parts of the world. However, caution should be taken when handling the plant as its leaves and stem contain pyrrolizidine alkaloids that can be poisonous if ingested.
Light Requirements
Senecio johnstonii Oliv. subsp. cheranganiensis requires abundant sunlight for optimal growth. The plant prefers full sun exposure, but it can also tolerate partial shade.
Temperature Requirements
The ideal temperature range for Senecio johnstonii Oliv. subsp. cheranganiensis is from 20 to 30 degrees Celsius. The plant can tolerate high temperatures up to 35 degrees Celsius, but it cannot survive in freezing conditions.
Soil Requirements
The plant prefers well-drained soils that are rich in organic matter. The soil pH should be slightly acidic to neutral, ranging from 5.5 to 7.5. Senecio johnstonii Oliv. subsp. cheranganiensis can grow in various soil textures, including sandy, loamy, and clay soils.
Cultivation Methods
Senecio johnstonii Oliv. subsp. cheranganiensis is a hardy, drought-resistant plant that is native to rocky soils at high altitudes. It thrives in full sun and well-draining soil, which can be achieved by mixing sand or perlite with the soil. The plant can tolerate temperatures as low as 20°F, making it suitable for cultivation in regions with mild winters.
Watering Needs
Senecio johnstonii Oliv. subsp. cheranganiensis is a succulent plant that stores water in its leaves. As such, it can tolerate long periods of dryness and should be watered sparingly. Once established, the plant can survive on natural rainfall or occasional watering during prolonged droughts. However, it is crucial to avoid overwatering, which can lead to root rot.
Fertilization
Senecio johnstonii Oliv. subsp. cheranganiensis does not require regular fertilization. However, adding a small amount of balanced, slow-release fertilizer to the soil during the growing season can enhance the plant's growth and flowering. It is advisable to dilute the fertilizer to half strength to avoid burning the plant's shallow roots.
Pruning
Senecio johnstonii Oliv. subsp. cheranganiensis does not require pruning to maintain its shape. However, removing dead or diseased leaves and stems can promote the plant's health and appearance. To prevent infection, it is essential to use sterilized pruning tools and to prune during the growing season when the plant can heal faster.
Propagation of Senecio johnstonii Oliv. subsp. cheranganiensis
Propagation of Senecio johnstonii Oliv. subsp. cheranganiensis can be done through several methods including:
1. Seed propagation
Seeds of Senecio johnstonii Oliv. subsp. cheranganiensis can be collected from mature plants during the flowering season. The seeds should be sown in a well-draining soil mixture in a container or seed tray. The container should be kept warm, moist, and in a bright location until the seeds germinate, which usually takes between 10-20 days. Once the seedlings develop 2-3 true leaves, they can be transplanted into individual pots.
2. Stem cutting propagation
Stem cuttings can be taken from mature plants during the growing season. The cutting should be approximately 10-15cm long, and can be taken from the tip or middle of the stem. Remove the lower leaves, leaving only a few leaves at the top of the cutting. Dip the cut end in rooting hormone powder and plant it in a well-draining soil mix. Keep the cutting moist and in a bright location, but out of direct sunlight. The cutting should develop roots within 4-6 weeks.
3. Division propagation
Senecio johnstonii Oliv. subsp. cheranganiensis can also be propagated through division. Divide the mature plant during the growing season, ensuring that each division has a good root system and several new shoots. Replant each division in a well-draining soil mix and keep it moist until it establishes.
Disease Management
Senecio johnstonii Oliv. subsp. cheranganiensis can be vulnerable to various kinds of diseases, including:
- Crown rot: A fungal disease that causes wilting and yellowing of leaves, and eventually, collapse of the crown of the plant. Crown rot can be caused by overwatering or poorly-draining soil. To manage crown rot, ensure soil drainage is adequate and avoid overwatering.
- Leaf spots: Fungal diseases that cause circular, brown-black spots on the leaves of the plant. Remove infected leaves and treat the plant with a fungicide, according to the manufacturer's instructions.
- Powdery mildew: A fungal disease that affects many plants, including Senecio johnstonii Oliv. subsp. cheranganiensis. It appears as a white, powdery substance on the leaves. To manage powdery mildew, remove infected leaves and treat the plant with a fungicide. Additionally, increase air circulation around the plant and reduce humidity to prevent powdery mildew growth.
Pest Management
Senecio johnstonii Oliv. subsp. cheranganiensis can also be vulnerable to certain pests, including:
- Spider mites: These tiny pests can cause leaf discoloration, wilting, and the appearance of webbing on the plant. To manage spider mites, spray the plant with water to wash off the pests, and use an insecticidal soap or oil, according to the manufacturer's instructions.
- Mealybugs: These small, white, cottony bugs feed on the sap of the plant and can cause stunted growth and yellowing of leaves. To manage mealybugs, wipe them off the plant with a damp cloth or cotton swab, or use an insecticidal soap or oil.
- Thrips: These small, winged insects cause distorted growth and discoloration on the leaves of the plant. To manage thrips, use an insecticidal soap or oil, according to the manufacturer's instructions. Additionally, maintaining a clean environment around the plant and removing any plant debris can be helpful in preventing thrips infestations.
