Sesamothamnus rivae is a distinctive succulent known for its prominent caudex and unique appearance. Its architectural form and adaptation to arid conditions make it a captivating choice for specialized plant collections.
Understanding Sesamothamnus rivae
Sesamothamnus rivae is a caudiciform shrub or small tree in the Pedaliaceae family. It features a thick, swollen caudex, up to 28 centimeters in diameter. The plant typically has sparse branching, small, bright green, oval leaves, and trumpet-shaped flowers, often white with a reddish throat.
Native to arid East Africa (Ethiopia, Tanzania, Somalia, northern Kenya), this species thrives in seasonally dry tropical climates. Its water-storing caudex enables adaptation to distinct wet and dry seasons and survival during drought.
Caring for Sesamothamnus rivae
Light Requirements
Sesamothamnus rivae thrives in bright, direct sunlight for optimal growth. Indoors, place it near a south-facing window or the brightest spot. Outdoors, choose a location with full sun exposure most of the day.
Watering Needs
Water Sesamothamnus rivae using a “soak and dry” method, allowing soil to dry completely between waterings. Overwatering is common and causes root rot. During the active growing season (warmer months), watering once a week may suffice; check soil moisture. During winter dormancy, reduce watering to about once a month, as leaves may drop and growth slows.
Soil and Potting
A well-draining, gritty succulent or cactus mix prevents root rot for Sesamothamnus rivae. An ideal mix includes loam for aeration. Choose terracotta or unglazed pots for air circulation and moisture evaporation. Ensure adequate drainage holes.
Temperature and Humidity
Sesamothamnus rivae prefers warm, frost-free conditions, above 10°C (50°F). It thrives in low humidity, typical of its arid habitat. Protect from sudden temperature drops in colder months, due to cold draft sensitivity.
Fertilization
Minimal fertilization is required for Sesamothamnus rivae due to adaptation to nutrient-poor environments. Apply a balanced, diluted succulent fertilizer sparingly during the active growing season. Avoid over-fertilization, which causes nutrient burn and harm.
Propagating Sesamothamnus rivae
Propagating Sesamothamnus rivae is primarily done through seeds or cuttings. For seeds, sow them in a well-draining mix in a warm, bright location; germination can be low or erratic, from days to six months.
For cuttings, take them during the active growing season. Allow cuttings to callus for several days before planting in a well-draining medium to prevent rot.
Addressing Common Issues
Root rot, caused by overwatering or poor drainage, is common. Symptoms include a soft caudex and yellowing leaves. Address this by reducing watering, drying soil, and ensuring drainage. In severe cases, repot with fresh, well-draining soil, trimming affected roots.
Pests like mealybugs and scale may occur. They appear as white, cottony masses or small bumps. Remove them manually with rubbing alcohol on a cotton swab, or apply insecticidal soap/neem oil.
Lack of growth or leaf drop may indicate winter dormancy. It can also signal insufficient light or water. If dormant, reduce water. Otherwise, ensure adequate light and watering for healthy growth.