Overview
Metrosideros collina (J.R. & G. Forst.) Gray var. newellii Rock is a flowering plant that belongs to the Myrtaceae family. It is commonly known as the Newell's lehua and is endemic to Hawaii. This plant is commonly found on the island of Kauai and is considered one of the rarest species of lehua.
Appearance
Newell's lehua is a small to medium-sized tree that grows up to 30 feet tall. It has a narrow, conical shape with smooth grayish-brown bark. The leaves are glossy and bright green with a leathery texture. They are oval-shaped and about 2 to 5 inches long. The flowers are showy and bright red, orange, or yellow. They are arranged in clusters at the end of the branches and bloom from December to June.
Uses
The Newell's lehua has traditional cultural significance in Hawaii. The plant was used in Hawaiian medicine for the treatment of various ailments, including fever, stomach ailments, and respiratory problems. The fragrant flowers were also used as a perfume and in lei-making. Due to its rarity, it is not commonly used for these purposes today.
In modern times, the plant is primarily grown as an ornamental tree for its showy flowers. It is popular among horticulturists and plant enthusiasts who are interested in the unique flora of Hawaii.
Conservation Status
The Newell's lehua is listed as an endangered species due to habitat loss, deforestation, and invasive species. The plant's natural habitat is threatened by human development, feral animals, and the spread of non-native plant species. Conservation efforts are being made to protect this rare plant, including habitat restoration and the creation of protected areas.
Light Requirements
Metrosideros collina var. newellii Rock thrives in full sun exposure and partial shade areas. It requires at least 6 hours of direct sunlight daily.
Temperature Requirements
The plant can tolerate a wide range of temperatures. However, it grows best in temperatures ranging between 10°C and 30°C. The plant can withstand frost but is not tolerant of extreme heat.
Soil Requirements
Metrosideros collina var. newellii Rock can grow in various soil types, but it does best in well-draining soils. The ideal soil pH should be between 5.5 and 7.5, but the plant can tolerate slightly acidic to slightly alkaline conditions. It is essential to avoid waterlogged soils as this can lead to root rot.
Cultivation of Metrosideros Collina Var. Newellii Rock
Metrosideros collina var. newellii Rock, commonly referred to as the Newell's Metrosideros, is a native plant of Hawaii. It is a tree species that can grow up to 33 feet tall. The following are some of the cultivation methods to consider when growing this plant:
- Planting: Choose a location with well-drained soil and full sunlight exposure. Dig a hole two times the size of the plant's root ball and plant the tree at the same depth as in its original container.
- Spacing: Space the trees about 15 to 20 feet apart from each other.
- Propagation: Propagation is usually achieved through cuttings and seeds. Seeds should be planted during spring in containers filled with well-draining potting soil and kept in a greenhouse.
- Temperature: These trees grow best in warm temperatures, with the ideal range being between 60°F to 80°F.
Watering and Fertilization
Proper watering and fertilization are essential in achieving optimal growth and health of your Metrosideros collina var. newellii Rock tree.
- Watering: Water the tree frequently during its first year to establish its roots thoroughly. Afterward, watering should be reduced. These plants are drought-tolerant and can survive periods of low rainfall.
- Fertilization: Fertilize the tree with a slow-release fertilizer about twice a year, in the spring and fall. This will provide the necessary nutrients for growth and will enhance the plant's resistance to disease and pests.
- Mulching: Adding organic mulch around the tree will help maintain moisture and improve the soil's fertility.
Pruning
Pruning your Metrosideros collina var. newellii Rock tree is essential during its growth to maintain its shape and health. Here are some tips on pruning:
- Prune the tree annually to develop a clear stem. Remove the lower branches as the tree grows to maintain a single trunk and a clear view of the tree's bark.
- Remove any diseased, damaged, or dead limbs to prevent the spread of diseases and pests.
- Prune after the tree's flowering season to promote new growth and maintain its desired shape.
By following these proper cultivation and care practices, your Metrosideros collina var. newellii Rock tree will grow beautifully and thrive for many years to come.
Propagation of Metrosideros collina var. newellii Rock
Metrosideros collina var. newellii Rock, commonly known as Newell's red lehua, is a native Hawaiian shrub or small tree that produces vibrant red flowers. It can be propagated through various methods:
Seed Propagation
Seed propagation is a common method of propagating Metrosideros collina var. newellii Rock. The seeds are collected from the red lehua flowers when they have turned brown. They should be sown in a well-draining, sterile potting mix, and covered lightly with soil. The pots should be placed in a warm area with bright, indirect light. The seeds will germinate in about 4 to 6 weeks.
Cuttings Propagation
Metrosideros collina var. newellii Rock can also be propagated through cuttings. The best time to take cuttings is in the early spring. Select a healthy stem about 6 inches long. Remove all leaves except for a few at the top. Dip the bottom end of the cutting in a rooting hormone powder and plant it in a well-draining, sterile potting mix. Keep the soil moist and place the pot in a shaded area. The cuttings will root in about 4 to 6 weeks.
Air Layering Propagation
Air layering is another option for propagating Metrosideros collina var. newellii Rock. This method involves creating a small wound on a stem, covering it with rooting hormone, and wrapping it with a moist sphagnum moss. The stem is then wrapped in plastic to create a humid environment. After several weeks, roots will develop from the wound. Once the roots are established, the stem can be cut and transplanted into a pot or directly into the garden.
Once rooted, Metrosideros collina var. newellii Rock can be transplanted into the garden or a larger container.
Disease Management
Metrosideros collina var. newellii is relatively resistant to diseases, but it can be affected by fungal and bacterial infections. The most common diseases that may affect the plant are:
Leaf Spot
Leaf spot is caused by the fungus Cercospora, which creates small, dark lesions on the leaves. The infected leaves may yellow and drop. To manage the disease, remove the infected leaves and dispose of them properly. Fungicides may also be used, but they should be applied as soon as the symptoms appear.
Fungal Rusts
Fungal rusts are caused by several species of Puccinia fungus, which induce small yellow spots on the upper surface of leaves that become reddish-brown pustules on the underside. The infected leaves may yellow and fall prematurely. To manage the disease, remove the infected leaves and dispose of them properly. Fungicides may also be used, but they should be applied as soon as the symptoms appear.
Bacterial Blight
Bacterial blight is caused by the bacteria Pseudomonas syringae, which induces the appearance of dark-green to black necrotic spots on the leaves. The infected leaves often curl and fall. To manage the disease, remove the infected leaves and dispose of them properly. Copper-based fungicides, as well as bactericides containing antibiotics, may be effective if applied properly.
Pest Management
Although Metrosideros collina var. newellii is not severely affected by pests, some insects may cause damage. The most common pests that may affect the plant are:
Aphids
Aphids are small insects that feed on the sap of the plant. They can cause the leaves to curl and turn yellow or brown. To manage the infestation, prune the affected leaves and shoot tips and spray the plant with a solution of water and insecticidal soap or neem oil.
Mites
Mites are tiny arachnids that feed on the leaves and cause them to turn yellow and fall. To manage the infestation, prune the affected leaves and spray the plant with a solution of water and insecticidal soap or neem oil.
Scale Insects
Scale insects are small, sap-sucking bugs that attach to the underside of the leaves and secrete a waxy coating that protects them from predators and insecticides. They can cause the leaves to turn yellow and fall. To manage the infestation, prune the affected leaves and spray the plant with a solution of water and insecticidal soap or neem oil. If the infestation is severe, horticultural oil may also be used.
