Polystachya shirensis Rchb.f. Description
Polystachya shirensis Rchb.f. is a beautiful and fascinating epiphyte that belongs to the Orchidaceae family. It is a native plant of the tropical and subtropical regions of Africa, specifically, the Democratic Republic of Congo, Kenya, Malawi, Tanzania, Zambia, and Zimbabwe. This orchid commonly grows in the forests and woodlands, usually in elevations between 1200 and 2000 meters above sea level. It is known by various common names, including the Shire River Polystachya, African Yellow Orchid, African Greenish-White Orchid, African Green Orchid, and East African Yellow Orchid.
General Appearance
Polystachya shirensis Rchb.f. is a medium-sized epiphytic orchid that typically grows up to 10 to 25 cm in height. It has pseudobulbs that are cylindrical or conical in shape, ranging from 3 to 7 cm long and 1 to 2 cm in diameter. The pseudobulbs are covered with several tightly overlapping leaf sheaths that form a pseudostem. Each pseudobulb can produce 2 to 4 leaves, which are leathery, oblong, or elliptic-shaped, and range from 10 to 30 cm in length and 1.5 to 4 cm in width.
The flowers of Polystachya shirensis Rchb.f. are arranged in a long and lax raceme, which can grow up to 30 cm in length and carry 10 to 20 flowers. The flowers have a bright yellow or greenish-white color and are small, about 0.5 to 1 cm in diameter. The lip is small and curved, and the sepals and petals are narrow and pointed.
Uses
Polystachya shirensis Rchb.f. is a popular ornamental plant that is widely cultivated as houseplants or in greenhouses. Its dainty and colorful flowers are charming and can add a splash of color to any collection of plants. This orchid is perfect for terrariums, as it thrives in high humidity and low light conditions.
In traditional African medicine, Polystachya shirensis Rchb.f. was used to treat ailments like wounds, skin rashes, and inflammation. Its pseudobulbs and roots were boiled to make a decoction that was applied to the affected areas as a poultice. However, there is no scientific evidence to support its medicinal properties, so caution is advised when using it for medicinal purposes.
Light Requirements
Polystachya shirensis Rchb.f. is an epiphyte and requires bright but indirect light. It grows well in areas with filtered light and should not be exposed to direct sunlight. A shaded location is ideal for the plant's growth.
Temperature Requirements
The plant grows well in warm temperatures ranging from 20°C to 30°C (68°F to 86°F). For optimal growth, the temperature should not drop below 18°C (64°F) or rise above 33°C (91°F). In colder climates, the plant can be grown indoors with a suitable heating system.
Soil Requirements
Polystachya shirensis Rchb.f. is an epiphytic plant that grows naturally on the bark of trees. The plant requires a well-draining, organic material-rich soil, which provides adequate moisture without retaining excess water. Orchid bark, sphagnum moss or a mix of both are ideal for the plant growth. The soil should be kept moist but not waterlogged. Proper aeration to the roots is a must for the plant growth.
Cultivation
Polystachya shirensis Rchb.f., also known as Shirendo Polystachya, is an epiphytic orchid species that grows in the wild. To cultivate at home, it is best to mimic its natural habitat by growing it on a piece of cork bark or in a basket.
The ideal temperature for growing Polystachya shirensis ranges from 15 to 25 degrees Celsius. It thrives under bright, indirect sunlight, which means that it needs to be protected from the direct rays of the sun.
Furthermore, proper air circulation is necessary for the plant since it is prone to fungal diseases due to its epiphytic nature. Hence, it is advisable to place the plant in a spot with good ventilation.
Watering Needs
Polystachya shirensis needs to be watered frequently, at least twice a week to keep the root system moist. However, avoid overwatering, as it can lead to root rot.
When watering, it is best to use warm or tepid water and avoid splashing the leaves as much as possible. In addition, do not let the plant stand in water, as it can trap moisture that leads to fungal and bacterial growth.
Fertilization
Feeding Polystachya shirensis is essential to keep it healthy, blooming, and thriving. You can use an orchid fertilizer with a balanced NPK ratio of 20-20-20.
However, do not apply more fertilizer than recommended, or it may damage the delicate roots of the plant. It is best to fertilize once or twice a month during the growing season and avoid feeding in the dormant season.
Pruning
Pruning is not necessary for Polystachya shirensis, except for the removal of dead, yellow, or damaged leaves.
If the plant has outgrown its habitat, it is best to transplant it by attaching it to a larger piece of cork bark or in a bigger basket. Avoid removing or trimming the roots unless it is damaged or dead, as it can compromise the plant's health.
Propagation of Polystachya shirensis Rchb.f.
Polystachya shirensis Rchb.f. can be propagated through several ways, including:
Division
Division is the most common method used to propagate Polystachya shirensis Rchb.f. This involves dividing the mature plant into smaller sections and replanting them. This method is often used when the plant has grown too large for its pot or when it becomes necessary to separate unhealthy or diseased sections. Each divided section should at least have one or two pseudobulbs, sufficient roots, and foliage. After replanting, it is important to water the plant and place it in a shaded area until the new roots are established.
Keiki
Keiki is a Hawaiian term that refers to baby orchids that grow on the stem or pseudobulb of a parent plant. Keikis can be detached from the parent plant when they have developed sufficient roots and foliage. After detaching, keikis can be planted in another pot with an appropriate growing medium, typically a mix of sphagnum moss, perlite, and bark. Keikis require high humidity and warm temperatures to root correctly, and it is important to avoid direct sunlight until fully established.
Seed propagation
Seed propagation is another method used to propagate Polystachya shirensis Rchb.f. This method is often used by professional growers to produce a large number of plants. Seeds should be planted in a germinating mix that is moist and free-draining. After planting, the pot should be covered with a clear plastic wrap or dome to maintain high humidity levels. It is important to keep the seeds warm and out of direct sunlight for effective germination. Once the seedlings are established, they can be transplanted to a larger pot with an orchid mix, where they can continue to grow to maturity.
Disease and Pest Management for Polystachya Shirensis Rchb.f.
Polystachya shirensis Rchb.f. is an epiphytic orchid that is native to tropical and subtropical regions. Like any other plant, it is prone to attack by pests and diseases. It is, therefore, critical to understand the common diseases and pests that might affect the plant and how to manage them.
Diseases
One of the most common diseases that affect Polystachya shirensis Rchb.f is bacterial soft rot. It is caused by bacteria that infect the plant through wounds or damage caused by pests. Bacterial soft rot causes the plant's tissues to become soft and slimy, ultimately leading to the plant's death. To manage this disease, affected parts must be removed from the plant and destroyed. Disinfecting tools used in pruning is also crucial in preventing the spread of the disease.
Another disease that affects Polystachya shirensis Rchb.f is leaf spot. It is caused by fungal infection and is prevalent in conditions of high humidity and poor air circulation. Leaf spot manifests as circular dark spots on the leaves, and if left unchecked, the leaves turn yellow and drop. To control leaf spot, remove affected leaves, and increase air circulation around the plant. Watering the plant early in the day and ensuring that the leaves remain dry can help prevent fungal infections.
Pests
One of the most common pests that affect Polystachya shirensis Rchb.f is mealybugs. Mealybugs are small, soft-bodied insects that feed on plant sap, causing the leaves to become yellow and distorted and slows its growth. To control mealybugs, remove them by hand and dab affected areas with rubbing alcohol. If the infestation is severe, insecticides with neem oil or insecticidal soap can be used.
Another common pest that affects Polystachya shirensis Rchb.f is spider mites. Spider mites feed on plant sap, causing leaves to become discolored and damaged. To manage spider mites, rinse the leaves with water frequently to keep them clean and dust-free. Applying insecticidal soap or neem oil can also help to control spider mites.
In conclusion, understanding common diseases and pests that affect Polystachya shirensis Rchb.f and how to manage them is crucial for the plant's health and longevity. Regular monitoring and preventive measures can help minimize the effects of pests and diseases on the plant.
