Overview
Dubautia imbricata St. John & G.D. Carr ssp. imbricata is a flowering plant that belongs to the sunflower family, known as Asteraceae. This plant is endemic to Hawaii and is found on the islands of Kauai, Oahu, and Molokai.
Common names
Dubautia imbricata is commonly known as the Ohele, Na'ena'e, or Na'ena'e'ole plant in Hawaii.
Appearance
Dubautia imbricata ssp. imbricata is a shrub or small tree that can grow up to ten feet tall. It has a single stem or multiple stems sprouting from the same root. The leaves of this plant are arranged opposite to each other and have oval or oblong shapes, with pointed tips, and can grow up to eight inches long and two inches wide. The flowers of this plant range from purple to lavender and can grow up to one inch in diameter. The fruits are tiny achenes, about 0.1 inches in length, with small white bristles on one end.
Uses
The Ohele plant is used in traditional Hawaiian medicine to treat various illnesses such as colds, coughs, and fever. The plant is rich in antioxidants and has anti-inflammatory and antimicrobial properties that may help with the treatment of these ailments. Additionally, the plant is used as an ornamental plant in gardens and landscapes due to its beautiful flowers and attractive foliage. The Ohele plant also has an ecological value as it provides a habitat and food source for various insect and bird species.
Light Requirements
The Dubautia imbricata ssp. imbricata is a plant that requires plenty of sunlight to develop and grow properly. In its natural habitat, it grows under full sun exposure, so direct sunlight will not damage it. This subspecies can adapt to partial shade but prefers a minimum of six hours of sunlight each day.
Temperature Requirements
The Dubautia imbricata ssp. imbricata grows best in areas that have a cool climate and a consistent temperature range. It prefers a temperature range of 12-24°C (55-75°F). If the temperature rises above this range, the plant may struggle to grow due to the increased rate of water loss through transpiration.
Soil Requirements
The Dubautia imbricata ssp. imbricata grows best in well-drained soils. The plant prefers volcanic cinder soil found in fumaroles and vents. This soil type is low in nutrients but has excellent drainage. The plant can tolerate low pH and is usually found in soils with a pH range between 4.5 and 6.5. This subspecies can tolerate a variety of soils as long as they are well-drained.
Cultivation
Dubautia imbricata St. John & G.D. Carr ssp. imbricata is best grown in full sun to partial shade. It is adaptable to a range of soil types, but prefers moist, well-drained soil. This plant is tolerant of wind and salt spray, so it can be a good choice for coastal gardens.
Watering Needs
During the growing season, Dubautia imbricata St. John & G.D. Carr ssp. imbricata prefers regular watering to keep the soil evenly moist. However, it does not tolerate standing water, so make sure the soil drains well. In winter, reduce watering to allow the plant to go dormant.
Fertilization
It is not necessary to fertilize Dubautia imbricata St. John & G.D. Carr ssp. imbricata, as it is adapted to grow in nutrient-poor soil. However, if the plant appears stunted or yellowing, you can apply a low-nitrogen, slow-release fertilizer in early spring.
Pruning
Dubautia imbricata St. John & G.D. Carr ssp. imbricata does not require intensive pruning, but deadheading spent flowers can encourage prolonged blooming. You can also shear the plant back by one-third after flowering to promote bushier growth and more flowers in the following year.
Propagation of Dubautia imbricata ssp. imbricata
Propagating Dubautia imbricata ssp. imbricata can be done through several methods:
Seed Propagation
Seed propagation is the most common method for propagating Dubautia imbricata ssp. imbricata. The seeds should ideally be collected when they are fully matured, as this results in higher germination rates. The seeds should then be sown in a well-draining soil mixture and kept moist. It is recommended to provide a temperature range of 15-20°C for optimal seed germination. The seedling growth is relatively slow, and it might take over a year for them to become mature enough for transplanting.
Cuttings
Propagation can also be done using cuttings from Dubautia imbricata ssp. imbricata. The cuttings should be taken from young, healthy shoots and should have at least two nodes. The cuttings should then be treated with rooting hormone and planted in a well-draining soil mixture. It is recommended to keep the soil moist and provide a temperature range of 15-20°C for optimal growth. The cuttings should root in 2-3 weeks, and before you know it, they will have grown into mature plants.
Division
Division is another propagation method that can be used to propagate Dubautia imbricata ssp. imbricata. The plants should be divided in early spring before the growing season begins. This can be done by gently removing the plant from the soil and dividing the plant's root system into smaller sections. Each section should have at least one complete stem and a healthy portion of roots. The new plants should then be planted in a well-draining soil mixture and kept moist. It is recommended to provide a temperature range of 15-20°C for optimal growth. The divided plants should take at least a year to reach maturity.
Disease and Pest Management for Dubautia imbricata St. John & G.D. Carr ssp. imbricata
Dubautia imbricata St. John & G.D. Carr ssp. imbricata, commonly known as the ‘Ahinahina or Mauna Kea silversword, is a rare and endangered plant species native to Hawaii. Although it has adapted to harsh environmental conditions, it is not immune to diseases and pests. Therefore, proper management is necessary to keep it healthy and thriving in its natural habitat and cultivated gardens. Here are some common diseases and pests that might affect Dubautia imbricata and suggestions for managing them.
Diseases
Fusarium
Fusarium is a soil-borne fungal disease that affects the roots of Dubautia imbricata, causing wilting, yellowing of leaves, and stunted growth. To manage Fusarium, plant resistant cultivars that are adapted to the specific soil and climatic conditions of the site. Avoid using contaminated soil and sterilize equipment before use. Monitor for early signs of infection and remove infected plants immediately to prevent the spread of the disease.
Black Root Rot
Black root rot is another soil-borne fungal disease that attacks the roots of Dubautia imbricata, causing root discoloration, decay, and death. To manage black root rot, avoid over-watering and waterlogging the soil. Use well-draining soil and provide adequate space for air circulation around the plant roots. Remove infected plants and replace the soil with fresh, sterilized soil.
Pests
Spider Mites
Spider mites are tiny arachnids that feed on the sap of Dubautia imbricata leaves, causing yellowing, bronzing, and wilting. To manage spider mites, spray the leaves with a gentle stream of water to dislodge the mites. Use insecticidal soap or neem oil to control severe infestations. Avoid using chemical pesticides that might harm beneficial insects and pollinators.
Caterpillars
Caterpillars, such as the silversword moth caterpillar, feed on the leaves and flowers of Dubautia imbricata, causing defoliation and reduced vigor. To manage caterpillars, handpick them from the plant and destroy them. Use Bacillus thuringiensis (BT) or spinosad, biological insecticides that target specific caterpillar pests. Avoid using broad-spectrum insecticides that might harm non-target insects.
By following the above suggestions for managing diseases and pests, gardeners and land managers can keep Dubautia imbricata healthy and beautiful for generations to come.
