Overview
Dubautia laxa Hook. & Arn., commonly known as N?wa?ak?a in Hawaiian, is a species of flowering plant in the sunflower family. It is endemic to the Hawaiian Islands and can be found on the islands of Maui, Moloka'i, Lana'i, and O'ahu.
Appearance
Dubautia laxa is a shrub or small tree with a height of up to 10 meters. Its leaves are dark green, pointed, and arranged alternately along the stem. The plant produces clusters of small, white or yellow flowers at the ends of its branches.
Uses
Traditional Hawaiian healers have used Dubautia laxa to treat infections, stomach pain, and bladder problems. The plant also has cultural significance, with its Hawaiian name, N?wa?ak?a, meaning "the sacred one." It is a popular plant among horticulturists due to its attractive, white flowers and tolerance for a variety of soil types.
Conservation Status
Dubautia laxa is classified as critically endangered due to its limited distribution and threats from habitat destruction, feral ungulates, and invasive plant species. Efforts are underway to protect and conserve the species through habitat restoration and seed banking.
Growth Conditions of Dubautia laxa Hook. & Arn.
Dubautia laxa Hook. & Arn., commonly known as nukuhiwa-gold, is a species of flowering plants native to the Hawaiian Islands. The plant is endemic to the island of Hawaii and is found in a variety of habitats, including dry to mesic forests, shrublands, and rocky slopes.
Light Requirements
Dubautia laxa requires full to partial sunlight for optimal growth. The plant is typically found in areas where it receives plenty of direct sunlight but can also grow in shaded areas that receive filtered sunlight.
Temperature Requirements
The nukuhiwa-gold plant grows well in warm temperatures between 15 to 30°C (59 to 86°F). Although the plant can tolerate slightly cooler temperatures, it cannot tolerate frost or extreme cold. Therefore, it is important to protect the plant from frosty conditions.
Soil Requirements
Dubautia laxa prefers well-drained soils that are rich in organic matter. The soil should be slightly acidic to neutral with a pH range of 5.5 to 7.5. The plant can grow in a wide range of soil types, including sandy, loamy, and clay soils. However, the soil must be well-draining to prevent waterlogging, which can lead to root rot.
Water Requirements
The nukuhiwa-gold plant requires moderate watering, with the soil remaining evenly moist during the growing season. However, it is essential to avoid overwatering the plant as it can cause root rot. In contrast, drought conditions can lead to stunted growth and may cause the leaves to wilt and drop off.
Fertilizer Requirements
Dubautia laxa benefits from regular fertilization during the growing season. The fertilizer should be high in nitrogen, phosphorus, and potassium, with micronutrients like iron, magnesium, and zinc. The frequency of fertilization and the amount of fertilizer required will depend on the soil and growth conditions of the plant.
Cultivation methods
The Dubautia laxa Hook. & Arn. is a plant native to Hawaii and prefers well-drained soil. The plant can tolerate different temperatures, from 50 to 60°F (10 to 15.5°C) during the winter and up to 75°F (24°C) in the summer. It grows well in partial shade or full sun. However, it also needs protection from strong winds, especially during flowering time. It can grow in pots, but it is preferable to plant Dubautia laxa Hook. & Arn. in the ground for optimal growth.
Watering needs
Dubautia laxa Hook. & Arn. needs a moderate amount of water to keep the soil moist, but not waterlogged. Once established, the plant can tolerate drought; however, make sure to water it regularly during the summer months. When the plant is young, water it frequently to help it establish its root system.
Fertilization
The Dubautia laxa Hook. & Arn. plant does not require frequent fertilization. Applying compost to the soil will provide the required nutrients. However, during the plant's active growth period, a low dose of balanced slow-release fertilizer can be applied to enhance the plant's growth.
Pruning
Dubautia laxa Hook. & Arn. requires minimal pruning. Cut back any overgrown or diseased branches as needed. The ideal time to prune is after blooming, typically in the late summer or early fall. Pruning at this time will encourage the plant to produce new growth, which will result in more flowers in the next growing season.
Propagation of Dubautia Laxa Hook. & Arn.
Dubautia Laxa Hook. & Arn. is propagated through both sexual and asexual means. For sexual propagation, the plant produces seeds that grow into new plants. Asexual propagation methods include stem cuttings and division of existing plants.
Sexual Propagation
The seeds of Dubautia Laxa Hook. & Arn. can be harvested when they mature. The flower head of the plant usually contains nearly ten cypselae that are hairy and rigid. When the cypselae are fully mature, they fall from the plant and can be collected and used for propagation. These collected seeds can be sown in pots filled with well-draining soil, ensuring the soil is moist. They need bright, indirect sunlight to germinate, which takes 2-4 weeks. The seedlings can be transplanted to individual pots once they mature enough to be handled.
Asexual Propagation
For asexual propagation through stem cuttings, select a healthy stem, free of any damage or pests. Cut the stem ensuring that it has at least one node, and remove any flowers or buds. Dip the cut end of the stem in hormone rooting powder and plant it in a well-draining potting mix. It should be kept moist and in a warm environment. The plant will take root in a few weeks.
Division is done by removing clumps and detaching them from the parent plant with a clean, sharp blade. After dividing the plant, each section should be transplanted separately in a pot with fertile soil, keeping in mind that each section has enough room to grow. The newly planted division should be kept indoors and warm, and they should be watered regularly until they establish roots and start growing.
Disease Management
Dubautia laxa is highly susceptible to several diseases. Some of the common diseases encountered by this plant species include:
- Leaf Spot
- Fungal Rusts
- Mold and Mildew
To manage these diseases effectively, a combination of cultural and chemical control methods is often recommended. These methods include:
- Pruning infected plant parts and removing them to prevent further spread of the disease.
- Providing proper spacing between plants to allow for proper air circulation.
- Regular application of fungicides such as copper-based fungicides or neem oil.
- Keeping the soil moist but not wet to prevent fungal growth.
Pest Management
Aside from diseases, Dubautia laxa is also vulnerable to numerous pests that suck sap and chew on its leaves. Some of the common pests that might affect this plant species include:
- Scale Insects
- Aphids
- Mealybugs
Effective management of these pests can be achieved through a combination of mechanical and chemical control methods. These methods include:
- Gently wiping infested plant parts with a soapy water solution.
- Trimming off heavily infested plant parts and disposing of them properly
- Regular application of chemical insecticides such as pyrethrin-based insecticides or neem oil.
- Applying sticky traps around the plant to capture and prevent pests from moving.
