Origin
Polyochnella welwitschii, also known as the Welwitsch's polycnemum, is a small flowering plant that belongs to the family Amaranthaceae. It is native to Angola and can also be found in Namibia.
Common Names
Besides Welwitsch's polycnemum, this plant goes by other common names, including knobwood, knobthorn, and khotani.
Uses
This plant has several medicinal properties and is used in traditional African medicine to treat various illnesses such as coughs, colds, rheumatism, and fever. The root bark is boiled in water and consumed as a beverage to treat stomach ailments, while the leaves are crushed and applied topically to relieve pain and inflammation. The plant also has potential use in the cosmetic industry due to its high tannin content, and can also be used as a source of firewood and charcoal due to its hard and dense wood.
General Appearance
Polyochnella welwitschii is a small tree with a crooked trunk that grows up to 10m high. It has a thick and rough bark and twisted branches that form a dense crown. The leaves are simple, alternate, and elliptical, with fine hairs on the underside and a shiny green top. The flowers are unisexual and inconspicuous, forming dense clusters at the base of the leaves. The fruit is a small, woody capsule, containing black seeds that are dispersed by wind.
Light Requirements:
Polyochnella welwitschii requires bright, indirect light to grow properly. Direct sunlight can damage the leaves and stunt the plant's growth. The ideal location for this plant is near a south-facing window that receives filtered sunlight.
Temperature Requirements:
This plant grows best in warm temperatures. The temperature range for optimal growth is between 15-30°C (59-86°F). At temperatures below 15°C (59°F), the growth rate slows down and can lead to stunted growth or even death of the plant.
Soil Requirements:
The soil for Polyochnella welwitschii should be well-draining and rich in organic matter. A combination of peat moss, perlite and sand is ideal for the plant's growth. A pH range between 6 and 7 is also suitable for the plant's growth. It is important to avoid overwatering, as this can lead to root rot.
Cultivation
Polyochnella welwitschii (Rolfe) Tiegh. is a terrestrial orchid that can be cultivated both indoors and outdoors. If grown indoors, it should be placed in a brightly lit area near a window that receives indirect sunlight. Outdoor cultivation should be done in areas where the plant can get partial shade.
The plant prefers well-draining soil with a pH range of 5.5 to 6.5. Organic potting mixes enriched with perlite, vermiculite, and peat moss are ideal for providing the right balance of moisture and nutrients.
Watering Needs
Polyochnella welwitschii (Rolfe) Tiegh. requires moderate watering. Watering should be done when the topsoil dries out. One should avoid overwatering or letting the soil dry out completely as it can damage the roots and lead to stunted growth or even death.
The plant can benefit from misting to maintain humidity levels, especially during summer when the air is dry.
Fertilization
Polyochnella welwitschii (Rolfe) Tiegh. should be fertilized every two weeks during the growing season with a balanced, water-soluble orchid fertilizer. Fertilizer should be diluted to half-strength to avoid overfeeding. During the dormant season, fertilization should be reduced to once a month.
Pruning
Polyochnella welwitschii (Rolfe) Tiegh. requires minimal pruning. One should remove dead, dry, or yellow leaves as soon as possible to prevent diseases or pests from spreading. Flower spikes should be pruned after flowering to promote new growth.
The plant should be repotted every two years to ensure adequate nutrients and room for growth. Repotting should be done after the flowering period, in spring or early summer.
Propagation of Polyochnella welwitschii
Polyochnella welwitschii (Rolfe) Tiegh. can be propagated by seed, stem cuttings and plant division.
Seed propagation
Seeds of Polyochnella welwitschii can be obtained from mature pods. The seeds should be sown immediately after collection in well-draining soil mixed with organic matter such as vermiculite or perlite, and kept moist. The ideal temperature for germination is between 18-25°C. Seedlings can be transplanted once they have developed true leaves.
Stem cutting propagation
Stem cuttings of Polyochnella welwitschii can be taken from mature plants during the growing season. Cuttings should be taken from the tips of stems and should be 8-10cm long with 2 or 3 leaves. Remove the lower leaves and dip the cut end in rooting hormone. Plant the cuttings in a well-draining soil mix and keep moist. Cuttings should root within a few weeks and can be transplanted into larger pots once established.
Plant division propagation
Polyochnella welwitschii can be propagated through plant division. Mature plants can be dug up and divided into smaller sections with a sharp, sterile knife. Ensure each section has healthy roots and stems. Replant the sections in well-draining soil mix and keep moist. Divisions should establish quickly and can be transplanted into larger pots or the ground once established.
Disease Management for Polyochnella welwitschii
Polyochnella welwitschii is generally a healthy plant and is not affected by many diseases. However, there are some common diseases that can affect it, such as leaf spots and root rot.
To control leaf spots, infected leaves should be removed and destroyed immediately. Fungicides such as copper can also be used to treat the plant. Proper sanitation practices should be followed to avoid the spread of the disease.
Root rot can be managed by ensuring that the plant is not over-watered and that the soil has good drainage. Affected plants should be removed and destroyed to prevent the spread of the disease to other healthy plants.
Pest Management for Polyochnella welwitschii
Polyochnella welwitschii is not known to be greatly affected by pests. However, some of the common pests that can infest the plant include spider mites and mealybugs.
To control spider mites, regularly inspect the plant for any signs of infestation, particularly on the underside of the leaves. Any infected plant should be removed and destroyed immediately. Insecticidal soap or oil can also be used to control the mites.
Mealybugs can be controlled by wiping them off with a cloth soaked in rubbing alcohol. Insecticidal soap or oil can also be used to treat the plant. Proper sanitation practices should be followed to prevent the spread of the pests to other healthy plants.
