Origin of Gunnera molokaiensis St. John
Gunnera molokaiensis St. John is a flowering plant that belongs to the Gunneraceae family and is endemic to Molokai, the fifth-largest Hawaiian island, located in the northern part of the Hawaiian archipelago. It is a rare species of the herbaceous perennial that is only found in a few rocky cliff bases in the rainforest on Molokai's eastern side.
Common Names
Gunnera molokaiensis St. John is commonly known as Moloka’i giant water taro or H?welelau. The name 'water taro' comes from the plant's large leaves, which resemble the leaves of taro, a staple plant in Hawaiian cuisine.
Appearance
Gunnera molokaiensis St. John is known for its massive leaves that can grow up to 2.5 meters (8.2 ft) in diameter. The plant is a herbaceous perennial that has tall, erect stems that can reach up to 2 meters (6.6 ft) in height. The plant is typically found in wet, shaded areas and thrives in the cool, misty climates found on the eastern side of Molokai. The giant leaves of this plant have deeply lobed heart-shaped blades, with a slightly serrated margin. The lobes on the leaves are deeply indented, which creates a stunning and unique look.
Uses
Although the plant doesn't have any particular use, the leaves are so huge they are an attraction to visitors for taking pictures and exploring. It also plays an essential role in the ecosystem by providing the native fauna with food and habitat. The plant is a significant part of Hawaiian culture as it is associated with the legend of a beautiful woman named Hina who became the moon and is said to have lived on Molokai.
Growth Conditions of Gunnera molokaiensis St. John
Gunnera molokaiensis St. John is a rhizomatous perennial herb that grows best in wet, cool environments. The plant needs sunlight and water to grow and thrive.
Light Requirements
Gunnera molokaiensis St. John requires partially shaded to full sun conditions. The plant prefers indirect sunlight, and direct sunlight exposure during the hottest part of the day can cause the leaves to wilt and dry up. Therefore, it is ideal to grow the plant beneath the canopy of taller plants or partial shade.
Temperature Requirements
The preferred temperature range for Gunnera molokaiensis St. John is between 55 and 75 degrees Fahrenheit. The plant cannot tolerate extreme heat, and temperatures above 80 degrees Fahrenheit can cause the leaves to wilt or dry up. The plant prefers cooler temperatures and needs to be protected from prolonged exposure to extreme heat or sudden temperature changes.
Soil Requirements
Gunnera molokaiensis St. John prefers moist soil that is rich in organic matter. The plant needs a consistent supply of water, so the soil must not be allowed to dry out. In addition, the plant cannot tolerate waterlogged soil, so the soil must be well-drained. The ideal pH range is between 4.5 and 6.5.
The plant can tolerate some salinity but prefers soil with low salt levels. A layer of mulch or organic matter around the plant helps retain soil moisture and nutrients while also improving the soil structure.
It is also essential to note that Gunnera molokaiensis St. John is susceptible to fungal diseases if grown in poorly drained, wet soil. Therefore, adequate drainage and air circulation are necessary to prevent fungal growth.
Cultivation methods
Gunnera molokaiensis St. John is a large and fast-growing plant that requires a spacious location to thrive well. The plant grows well in fertile moist soil that is rich in organic matter. It needs to be placed in a spot that receives bright, indirect sunlight. The plant can tolerate cold temperatures to some extent but needs protection from frost.
Watering needs
Gunerra molokaiensis St. John loves moisture and requires regular watering to keep the soil moist. The amount of water that your plant needs will depend on the prevailing weather conditions in the area and the soil type. However, avoid overwatering and ensure that the soil is well-draining. During the hot summer months, frequent watering, preferably daily, is necessary to maintain healthy growth.
Fertilization
Proper fertilization is essential for the growth and survival of the plant. Gunnera molokaiensis St. John is a heavy feeder and needs nutrients like nitrogen, potassium, and phosphorus to thrive. Fertilize the plant on a monthly basis, preferably using organic-based fertilizers. The appropriate amounts of fertilizer depend on the age of the plant and the soil composition. Ensure that you water the plant after fertilizing to avoid leaf burn.
Pruning
Pruning is essential for maintaining the shape and size of the Gunnera molokaiensis St. John plant. The plant produces large leaves that can obstruct the view. You can prune the leaves to thin out the plant, allowing light to penetrate the interior. However, avoid excessive pruning as it can lead to stunted growth. You should also remove any dead or damaged leaves or stems to prevent rotting. Pruning is best done during the plant's dormant season to avoid interfering with its growth.
Propagation of Gunnera molokaiensis St. John
Gunnera molokaiensis St. John can be propagated by seed, division, and tissue culture.
Seed Propagation
Seed propagation of Gunnera molokaiensis St. John is possible but can be a bit tricky. Seeds should be sown in early spring in a mixture of peat moss and perlite. The container should be placed in a warm, humid location with a constant temperature of around 70 degrees Fahrenheit. Germination can take up to several months.
Division Propagation
The most common way to propagate Gunnera molokaiensis St. John is through division. This method involves separating the mature plant into smaller sections. Each section should have a portion of the root system and at least one healthy foliage shoot. The new sections should be planted in rich, moist soil in a location that receives partial sun.
Tissue Culture Propagation
Tissue culture propagation is a newer technique that involves growing new plants from small amounts of plant tissue. This method is useful for producing large numbers of identical plants for research or commercial purposes. Tissue culture propagation requires specialized equipment and expertise and is not typically used by home gardeners.
Disease and Pest Management for Gunnera molokaiensis St. John Plants
Gunnera molokaiensis St. John is a plant that is susceptible to various pest problems and diseases. As such, it is crucial to take precautions to prevent them from affecting the plant significantly. Some of the common pests and diseases that afflict Gunnera molokaiensis St. John plants are discussed below, along with some tips on how to manage them.
Pests
1. Spider Mites: Spider mites are one of the most common pests that infest Gunnera molokaiensis St. John plants. They suck the sap from leaves, causing them to become dry, discolored, and sometimes drop. You can control spider mites by hosing the plant with water to remove the pests, introducing predatory bugs like ladybugs and lacewings, or spraying the plant with insecticidal soap or neem oil.
2. Slugs and Snails: Slugs and snails are troublesome pests capable of causing severe damage to the leaves of Gunnera molokaiensis St. John plants. They leave slime trails, chew holes in the leaves, and eat the plant's flowers. You can control slugs and snails by handpicking them, laying a trap, applying diatomaceous earth or spreading copper barriers around the plants.
Diseases
1. Crown Rot: If you notice your Gunnera molokaiensis St. John plant's crown is rotting, and the leaves appear yellow and wilted, it could be an indication of crown rot. This disease occurs as a result of overwatering the plant or planting it in poorly drained soil. To prevent crown rot, ensure that the plant soil has adequate drainage and avoid overwatering.
2. Powdery Mildew: Powdery mildew is a fungal disease that attacks the leaves of Gunnera molokaiensis St. John, making them look powdery and gray. This disease thrives in damp weather and is likely to develop when there is limited airflow. To control powdery mildew, ensure proper plant spacing, increase airflow, avoid watering from above, and use a fungicide as necessary.
3. Leaf Spot: Leaf spot is a fungal disease that causes circular brown spots on the leaves of Gunnera molokaiensis St. John. It is usually caused by overwatering, overcrowding, and humidity. To prevent leaf spot, ensure proper spacing, allow for enough airflow, and avoid overhead watering. Fungicides can also help to manage the disease.
By taking preventative measures against pests and diseases and tackling them early, you can ensure your Gunnera molokaiensis St. John plant remains healthy and thrives. Remember to observe proper plant care, such as avoiding overwatering and ensuring proper drainage.
