Origin:
Metrosideros polymorpha Gaud. var. glabrifolia, also known as ?Ohi?a lehua, is a flowering plant that belongs to the family of Myrtaceae. The species is endemic to Hawaii and is one of the most common trees found in the Hawaiian Islands. It can grow up to 15-25 meters tall and is known to thrive in wet and dry environments, which is why it is often found in rainforests, dry forests, and subalpine habitats.
Common Names:
?Ohi?a lehua is the most common name for Metrosideros polymorpha Gaud. var. glabrifolia in Hawaii. The name ?Ohi?a refers to the tree, while lehua refers to the flower. Other common names include lehua, lehua tree, and lehua ohia.
Uses:
?Ohi?a lehua holds a significant cultural and ecological importance in Hawaii. The plant was used by Native Hawaiians for food, medicine, and religious purposes. The flowers of the lehua tree were particularly valued for their bright red color and were often used in traditional Hawaiian hula dances. The plant also serves as an important host for native birds, including the Hawaiian honeycreeper, which feeds on the nectar of the lehua flower.
General Appearance:
?Ohi?a lehua is a large, evergreen tree with a rounded canopy. It has smooth, reddish-brown bark and relatively small, oval-shaped leaves that are dark green on the upper side and light green on the underside. The lehua flower is a bright red to pink color and is a common sight in Hawaiian forests from late summer to early winter. The plant is also known for its dense, fibrous root system, which allows it to thrive in a variety of soil types and conditions.
Light Requirements
The Metrosideros polymorpha Gaud. var. glabrifolia (Heller) St. John typically grows in full sunlight. It thrives in areas with bright and direct sunlight for at least six hours daily. In shaded areas, the plant tends to grow taller with limited foliage, making it less attractive. Therefore, placing the plant in a well-lit position is necessary for its growth and development.
Temperature Requirements
The plant thrives under warm temperatures typically found in tropical to subtropical climates. Temperature fluctuations may affect its growth, and it sustains the optimum growth rate in temperatures ranging from 19 °C to 29 °C. During the winter months, the plant becomes dormant and seems to stop growing, but it starts to grow again once the warm temperatures return.
Soil Requirements
The Metrosideros polymorpha Gaud. var. glabrifolia (Heller) St. John prefers a well-draining, slightly acidic soil with a pH of 5.5 to 6.5. It is recommended to use soil that is composed of fertile loam, coarse sand, and organic matter. Additionally, the soil should contain enough nutrients required for the growth of the plant. Overwatering should be avoided as it may lead to the development of root rot disease. Therefore, watering the plant when the surface soil has been dry for a few days would be ideal.
Cultivation
Metrosideros polymorpha Gaud. var. glabrifolia (Heller) St. John, commonly known as the smooth-leaved 'ohi'a lehua, is native to Hawaii and highly valued for its beauty and cultural significance. This plant species can grow up to 40 feet tall with a spread of 15-20 feet, so it's important to plant it in a spacious area with ample room to grow.
The plant prefers well-draining soils with a pH range of 4.5-7.5. Make sure to plant it in a spot with lots of sunlight, and shelter it from strong winds and excess moisture. It can be propagated from both seeds and cuttings.
Watering
While the 'ohi'a lehua can tolerate periods of drought, it prefers regular watering, especially during the dry season. Keep soil moist but not waterlogged, as too much water can lead to root rot. When watering, try to avoid wetting the leaves, as this plant is susceptible to leaf spot disease.
Fertilization
The 'ohi'a lehua thrives in nutrient-rich soils, so it's essential to fertilize it regularly. Use a balanced, slow-release fertilizer with a higher concentration of phosphorous to encourage blooming. Fertilize every 2-3 months during the growing season, but reduce frequency during the winter months.
Pruning
The 'ohi'a lehua should be pruned during the dormant period (winter). Remove any dead or diseased branches, as well as any growth that is crossing or rubbing against other branches. Prune selectively to maintain a natural shape and never remove more than one-third of the plant's foliage at once.
Propagation of Metrosideros polymorpha Gaud. var. glabrifolia
Metrosideros polymorpha Gaud. var. glabrifolia (Heller) St. John, commonly known as ?hi?a ha, is a Hawaiian endemic shrub that belongs to the Myrtaceae family. This variety thrives at elevations ranging from 1,500 to 8,000 feet and is found in both dry and wet forests.
Propagation of ?hi?a ha can be achieved through different methods, including:
Seed Propagation
The seeds collected from ?hi?a ha are typically small, and approximately 100,000 seeds weigh about 1 kg. The seeds should be sown immediately to prevent loss of viability. A suitable potting mixture consisting of peat moss, loam, and sand should be used. After sowing, the mixture should be covered with a thin layer of sand, and the pot should be kept in shade with adequate humidity until germination.
Cuttings Propagation
Cuttings from mature ?hi?a ha trees can be used for propagation. Semi-hardwood cuttings, that is, those that have matured enough to become woody but are not fully mature, can be used for propagation. The cutting should be between 4 to 6 inches long and made from new wood. The lower leaves should be removed, and the cutting dipped in rooting hormone. The cutting is then placed in a pot filled with a suitable potting mixture and kept in shade with adequate humidity until roots develop.
Air-layering Propagation
Air-layering is another method used for propagating ?hi?a ha. The bark is removed from a 2-3 inch section of the middle stem, and rooting hormone is applied. The exposed section is then wrapped in moist sphagnum moss and covered with clear plastic wrap to prevent moisture loss. Roots can develop within weeks, and once they are established, the rooted section can be severed from the parent plant and potted.
Disease and Pest Management for Metrosideros polymorpha Gaud. var. glabrifolia (Heller) St. John
Metrosideros polymorpha Gaud. var. glabrifolia, commonly known as the Hawaiian Christmas tree or ??hi?a Lehua, is a species of flowering tree in the myrtle family, Myrtaceae. It is endemic to Hawaii and can be found growing in various habitats, from lowland forests to high-elevation shrublands. Like any other plant, the Hawaiian Christmas tree is susceptible to certain diseases and pests that can affect its growth and ultimately lead to its demise. Here are some common diseases and pests that affect this plant and ways to manage them:
Diseases
Rapid Ohia Death (ROD)
ROD is a disease caused by two closely related fungi, Ceratocystis fimbriata and Ceratocystis lukuohia, that enter the tree either through wounds or natural openings. The disease can kill an ??hi?a tree within weeks to months, depending on the severity of the infection. To manage ROD, it is important to prevent the spread of the disease by avoiding unnecessary contact with infected trees, cleaning tools and equipment used on infected trees, and following quarantine regulations in affected areas.
Leaf Spot
Leaf spot is a fungal disease that affects the leaves of the plant, causing circular or irregular brown spots with yellow edges. To manage this disease, it is important to remove infected leaves and dispose of them properly. Fungicides may also be used, but it is important to consult with a professional to determine the most effective treatment.
Pests
??hi?a Gall Wasp
The ??hi?a gall wasp is a small insect that lays eggs on the new shoots of ??hi?a trees, causing the tree to form galls that can stunt its growth and ultimately lead to its death. To manage the ??hi?a gall wasp, it is important to monitor trees for early signs of infestation and to prune and dispose of infected shoots. Insecticides may also be used, but they should be used sparingly and only under the guidance of a professional.
Hawaiian Hoary Scale
The Hawaiian hoary scale is a small insect that feeds on the sap of ??hi?a trees, causing leaves to turn yellow and drop prematurely. To manage this pest, it is important to inspect trees regularly for signs of infestation and to prune and dispose of infected branches. Insecticides may also be used, but it is important to consult with a professional to determine the most effective treatment.
Overall, managing diseases and pests in Metrosideros polymorpha Gaud. var. glabrifolia requires careful monitoring and prompt action to prevent the spread of infection and maintain the health and vitality of the plant. It is also important to consult with a professional to determine the most effective treatment options.
