Origin
Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong, commonly known as robust naiad, is a species of aquatic plant belonging to the family Hydrocharitaceae. It is native to North America and can be found in many regions across the continent.
Common Names
This aquatic plant is commonly known as robust naiad because of its strong and healthy appearance. It is also known by other names such as flexible naiad, northern naiad, and wild celery.
Uses
Robust naiad is an important plant in aquatic ecosystems as it provides food and habitat for aquatic animals and birds. It is also used as an indicator for water quality and environmental health. In addition, the plant is known to have medicinal properties and is used in some traditional medicines for treating certain ailments.
General Appearance
Robust naiad is a perennial plant that has long, thin, and flexible leaves that are arranged in spirals along the stem. The plant can grow up to 3 meters in length and has small, inconspicuous flowers that are greenish-white in color. The leaves of the plant are shiny green and the plant has a bushy appearance when grown densely. The plant is usually found in shallow freshwater bodies like lakes, ponds, and slow-moving streams or rivers.
Light Requirements
Najas flexilis var. robusta prefers bright light, but it can also survive under low light conditions. There should be sufficient light penetration for photosynthesis to occur. Under low light conditions, the plant may grow taller, with longer internodes and fewer leaves.
Temperature Requirements
The optimal temperature for Najas flexilis var. robusta is between 18°C to 28°C. Extreme temperatures can affect its growth and survival. The plant can tolerate a wide range of temperatures but can die off if the water temperature falls below 10°C or rises above 30°C for an extended period.
Water Requirements
Najas flexilis var. robusta requires clean, freshwater to grow. The pH of the water should be between 6.5 and 7.5. The plant can tolerate salinity levels of up to 2ppt, but it grows better in freshwater. The depth of the water should be at least 30 cm for optimal growth and development.
Soil Requirements
Najas flexilis var. robusta grows well in a nutrient-rich substrate. The soil should be well-aerated, with loose texture for easy root penetration. The plant is mainly anchored in the substrate by its roots, which are relatively thin and delicate, so the substrate should not be too coarse.
Cultivation Methods
Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong is a submerged aquatic plant that thrives in calm, clear water bodies such as ponds, lakes, and slow-moving streams. It requires plenty of sunlight to grow, making it ideal for cultivation in outdoor ponds exposed to full sunlight.
The plant grows from rhizomes, and so planting is done by burying the rhizomes in the substrate. Plant the rhizomes at a depth of 12-18 inches in the substrate to prevent them from being uprooted by fish and other aquatic animals. Applying a thin layer of gravel on top of the substrate can help hold the rhizomes in place.
Watering Needs
Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong thrives in clean water with a temperature range of 60-80°F. It requires low to moderate water currents, and the water level should be at least 20 inches deep for optimal growth.
Regular water changes help maintain the water quality and prevent accumulation of rotting organic matter, which can stunt the plant's growth. The plants do not require watering as such but strive in slightly alkaline to neutral water (pH 6.5-8.0) with sufficient nutrients, carbon dioxide, and oxygen.
Fertilization
Regular fertilization is crucial for promoting the growth and development of Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong. A balanced aquatic plant fertilizer containing nitrogen, phosphate, and potassium can provide the necessary nutrients to the plant. It would be best to fertilize the plant during its growing season, which is typically in spring and summer.
It is essential to adhere to the recommended dosage on the fertilizer packaging to prevent nutrient excess, which can lead to poor water quality and algal bloom.
Pruning
Pruning is an essential aspect of Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong cultivation as it helps to maintain the plant's shape and size while promoting healthier growth. Trim any dead or damaged leaves and stems regularly to improve the plant's appearance and encourage new growth.
It is best to prune the plant in early spring before the start of the growing season to prevent overcrowding. Use scissors or pruning shears to trim the plant and ensure that the tools are clean and sharp to minimize damage to the plant. Be careful not to over-prune as this can negatively impact the plant's health and limit its growth potential.
Propagation of Najas flexilis var. robusta
Najas flexilis var. robusta can be propagated through several methods, such as:
Seed Propagation
Seeds of Najas flexilis var. robusta can be collected from the plant during fruiting season and sown directly into the soil. The best time to sow the seeds is in the early spring season. The seeds should be planted in shallow water and should be evenly spread in the water. The seeds will germinate within a few weeks, and the seedlings will reach maturity in one year.
Vegetative Propagation
Najas flexilis var. robusta can also be propagated vegetatively through stem cuttings or runners. Whether propagating via stem cuttings, make sure that each cutting is about 10-20 cm long. For runners, the best time to propagate is in the spring growing season. Runners should be separated from the parent plant and planted in shallow water. The plant will establish in a few weeks.
Division Propagation
Another propagation method used for Najas flexilis var. robusta is by dividing the roots. Divide the roots in early spring or late summer and plant them in shallow water. Each division should have a minimum of three shoots to ensure successful propagation.
Disease and Pest Management for Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong
Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong is generally a hardy plant species, but it is still susceptible to various diseases and pests that can damage or kill it. Some of the common diseases and pests that might affect this plant include:
Diseases
Fungal diseases such as root and stem rot, leaf spot, and powdery mildew can damage Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong. To manage these diseases, ensure that the plant grows in well-drained soil, and avoid overwatering. Remove any infected leaves or stems as soon as possible and apply fungicide to prevent the spread of fungus.
Pests
Several insects can feed on Najas flexilis (Willd.) Rostk. & Schmidt var. robusta Morong, such as aphids, snails, and slugs. These pests can weaken the plant, cause leaf and stem damage, and even kill the plant if not controlled. To manage these pests, apply insecticides, use organic control methods like neem oil or insecticidal soap, or manually remove them by handpicking.
Another pest that can affect this plant is the whitefly. These tiny insects suck sap from leaves and transmit viral diseases. To manage whiteflies, introduce natural predators like ladybugs or lacewings, apply insecticidal soap, or use sticky traps.
Finally, the Najas flea beetle can also damage the leaves of this plant, causing tiny holes that eventually kill the leaves. To manage these pests, remove any infected plant debris or weeds, apply insecticides, or introduce natural predators like parasitic wasps or lacewing larvae.
