Origin
Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John is a plant species belonging to the Rutaceae family. It is endemic to Hawaii, particularly in the islands of Maui, Kauai, and Oahu.
Common Names
Zanthoxylum dipetalum Mann var. hillebrandii is commonly known as Hillebrand's Pelea or Alani in Hawaii. In some instances, it is also referred to as a Hawaiian prickly ash or a Lemonwood tree.
Appearance
The plant usually grows up to 10-30 feet tall with a trunk ranging from 1-3 feet in diameter. Z. dipetalum var. hillebrandii has a smooth, grey bark that peels as it ages. Its leaves are pinnate and arranged alternately along the branches, with each leaflet measuring around 1-2 inches in length. The tree produces small flowers that grow in clusters on the branches and are typically yellow in color. The plant bears fruit that resembles a small brownish capsule, which contains one or two shiny black seeds.
Uses
Zanthoxylum dipetalum var. hillebrandii has a strong cultural significance among the Native Hawaiians, as its bark and leaves were used in traditional medicine. The plant also possesses antimicrobial properties and is commonly used as an insect repellent. The bark and fruits of the plant have a strong aroma and are used to flavor dishes in traditional Hawaiian cuisine. In addition, Z. dipetalum var. hillebrandii is a popular ornamental tree, planted in parks and gardens for its bright green leaves and small yellow flowers.
Light Requirements
Zanthoxylum dipetalum Mann var. hillebrandii requires full to partial sun exposure. The plant can tolerate direct sunlight but thrives better in a partially shaded area.
Temperature Requirements
The plant grows optimally between 20°C to 30°C (68°F to 86°F). The minimum and maximum temperature range for growth are 10°C (50°F) and 35°C (95°F), respectively. It is important to avoid exposing the plant to temperatures below 10°C and above 35°C as it may cause irreversible damages to the plant.
Soil Requirements
Zanthoxylum dipetalum Mann var. hillebrandii prefers well-drained, fertile, and loamy soil. The soil should be rich in organic matter and have a pH range of 5.5 to 6.5. It can tolerate a wide range of soil textures, but too much clay in the soil can cause poor drainage and inhibit growth. When planting this shrub, it is advisable to amend the soil with compost or any other organic matter to improve soil quality.
Cultivation Methods for Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John
Zanthoxylum dipetalum Mann var. hillebrandii is an evergreen tree that adapts well to different climatic conditions. It is a hardy plant that prefers well-drained soil and partial to full sun. When planting, the appropriate hole should be dug, depending on the size of the root ball.
The soil should be loosened and mixed with organic compost before planting the tree. This helps to retain moisture and provide nutrients to the plant roots. The plant should be watered adequately after planting until it becomes established in the new environment. This usually takes a couple of weeks.
Watering Needs for Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John
Water is essential for the growth of Zanthoxylum dipetalum Mann var. hillebrandii. For optimal growth of the plant, it should be watered regularly. The plant should not be allowed to dry out between waterings. However, too much water can cause root rot and affect the overall health of the plant.
During the hot summer months, the plant may require more frequent watering to sustain the moisture levels in the soil. Care should be taken not to sprinkle water on the leaves, as the leaves may scorch. It is advisable to use a watering can or a drip system to water the plant and ensure that the water reaches the root system.
Fertilization for Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John
Regular fertilization is necessary for the proper growth and development of Zanthoxylum dipetalum Mann var. hillebrandii. The plant should be fertilized every six months using a slow-release fertilizer that is high in nitrogen, phosphorus, and potassium.
The fertilizer should be spread around the base of the plant and watered in thoroughly. Care should be taken not to apply too much fertilizer as this can burn the roots and damage the plant. It is advisable to follow the manufacturer's instructions when applying fertilizers.
Pruning for Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John
Pruning is essential for the aesthetic and functional purposes of Zanthoxylum dipetalum Mann var. hillebrandii. The plant should be pruned annually to remove dead or diseased branches and maintain the desired shape.
The best time to prune the plant is during the dormant season, which is usually in the winter months. If the plant is pruned during the growing season, it may result in the loss of flowers or fruits.
Care should be taken not to prune too much of the plant, as this may stunt its growth and reduce its aesthetic appeal. Also, it is advisable to use pruning tools that are sharp and clean to avoid spreading diseases.
Propagation of Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John
Zanthoxylum dipetalum Mann var. hillebrandii (Sherff) St. John, commonly known as Hawaiian prickly ash, is a small tree endemic to Hawaii. It produces distinctive, citrus-scented leaves and flowers and is used for culinary and medicinal purposes. To propagate this plant, there are two primary methods: seed propagation and stem cuttings.
Seed Propagation
Seed propagation is the most common method for propagating Zanthoxylum dipetalum Mann var. hillebrandii. The seeds are readily available from mature plants or from online retailers. To begin, the seeds should be cleaned and soaked in water for 24 hours to promote germination. After soaking, the seeds can be planted in a well-draining soil mixture and covered lightly with soil. The soil should be kept moist but not waterlogged, and the seeds should sprout within 2-4 weeks. Once the seedlings reach 6-8 inches tall, they can be transplanted into larger pots or directly into the ground.
Stem Cuttings
Propagation of Zanthoxylum dipetalum Mann var. hillebrandii through stem cuttings is possible but less common than seed propagation. Softwood cuttings should be taken from the plant in the early summer, when the new growth is still soft and pliable. The cuttings should be 4-6 inches long and have at least three sets of leaves. Remove any leaves from the bottom inch of the stem and dip the cut end of the stem in rooting hormone. Insert the stem into a well-draining soil mixture and keep it moist. The cutting should root within 4-6 weeks. Once rooted, the new plant can be transplanted into a larger pot or directly into the ground.
Disease management
Zanthoxylum dipetalum Mann var. hillebrandii, commonly known as Hawaiian toothache tree, is susceptible to several diseases that can cause damage to the plant. One of the most common diseases the plant can suffer from is anthracnose. This fungal disease may appear as dark brown spots on the leaves or as sunken lesions on stems and fruits. To manage anthracnose, it is recommended to remove the diseased parts and dispose of them properly. Additionally, treating the plant with a fungicide can help reduce the risk of anthracnose.
Another disease that can affect Hawaiian toothache tree is powdery mildew. This fungal disease can result in a white powdery coating on leaves, stems, and flowers, causing them to turn yellow and eventually die. To manage this disease, it is recommended to prune affected parts of the plant and apply a fungicide to prevent further growth of the fungus.
Pest management
Hawaiian toothache tree can also be attacked by pests that can cause severe damage to the plant, including the citrus longhorned beetle, scale insects, and spider mites. The citrus longhorned beetle can cause damage to the bark and wood of the plant, leading to stunted growth or death. To manage this pest, it is recommended to remove infected trees and destroy them to prevent further spread.
Scale insects are another pest that can be found on this plant. They are small sap-sucking insects that can cause yellowing of the leaves, stunted growth, and even death. To manage this pest, it is recommended to prune affected parts of the plant and apply insecticides to prevent further infestations.
Spider mites may also attack Hawaiian toothache tree, causing damage to the leaves and stems. These pests are tiny and often difficult to detect. However, their damage can be seen in the form of yellowed leaves and defoliation. To manage this pest, it is recommended to spray the plant with water to remove the mites and apply miticides to prevent further infestations.
