Origin:
Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns, commonly known as the tall lettuce, is a member of the Asteraceae family, which is primarily found in Asia. This plant is native to China, Korea, Japan, and Russia.
Common Names:
The tall lettuce is also commonly known as the Chinese lettuce and the Korean lettuce. Additionally, it is referred to as "Wild Lettuce," although this name is often used interchangeably with other species of the Lactuca genus.
Uses:
The tall lettuce has traditionally been used in Chinese medicine as a remedy for chest congestion and to treat coughs and throat irritation. The leaves and stems of the plant contain lactucin, lactucopicrin, and other compounds that have sedative and analgesic effects. As a result, it is also used as a natural treatment for insomnia and anxiety. Besides medicinal purposes, the plant is also cultivated for its ornamental value due to its attractive flowers and leaves.
General Appearance:
The tall lettuce is a perennial plant that can grow up to 2 meters (6.5 feet) tall. The leaves grow alternately along the stem, and the basal leaves are more significant than the upper ones. The leaves are ovate to lanceolate in shape and can reach up to 30 centimeters (12 inches) in length. The plant produces yellow or orange flowers that bloom in mid-summer. The flowers are arranged in panicles standing atop the branched stems. The entire plant exudes a milky white sap when bruised or broken.
Light Requirements
Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns generally prefers full sun to partial sun exposure. It can tolerate moderate shade, but too much shade can result in weakened growth and reduced flowering ability.
Temperature Requirements
This plant thrives in a cool-temperate climate and is hardy in USDA hardiness zones 3-7. It prefers temperatures ranging from 10-24°C (50-75°F), with a cooler temperature range being optimal for growth. High temperatures above 27°C (80°F) can cause heat stress and reduce the plant's growth rate.
Soil Requirements
Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns prefers moist, fertile soils with good drainage. It can tolerate a range of soil types, from sandy to loamy. The ideal pH range for this plant is 6.0-7.5, but it can tolerate slightly acidic to slightly alkaline soils. It is also important to note that this plant can be invasive in areas with moist, fertile, disturbed soils, so it is recommended to monitor its growth and prevent it from spreading.
Cultivation Methods
Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns, commonly known as glandular lettuce, is a biennial plant belonging to the family Asteraceae. This plant is best cultivated in a sunny spot with fertile, well-drained soil. It thrives in cool temperature conditions, making it ideal for cultivation in regions with mild summer temperatures. The seeds of glandular lettuce can be sown directly into the soil, and the plant can also be propagated through stem cuttings.
Watering Needs
Proper watering is key to the growth and development of glandular lettuce. This plant requires consistent and even watering, especially during its initial growth period. Avoid overwatering, as this can lead to root rot and other soil-borne diseases. To avoid fungal growth, it is best to water the plant in the morning and avoid getting the leaves wet. Once the plant has established, it can tolerate some level of drought, but it is advisable to water it regularly during the summer months.
Fertilization
Glandular lettuce requires regular fertilization to ensure healthy growth and development. A balanced fertilizer with equal parts nitrogen, phosphorous, and potassium is best for this plant. Fertilizers should be applied during the early stages of growth and every few weeks for continued growth. Avoid over-fertilizing, as this can harm the plant and lead to stunted growth and pest infestations.
Pruning
Pruning glandular lettuce is not a necessary practice, as this plant does not require it for proper growth. However, removing dead or yellow leaves and thinning out overcrowded areas can improve overall plant health and reduce the risk of pests and diseases. Additionally, cutting the flowering stems can prolong the plant's vegetative growth and increase yield.
Propagation of Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns
The Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns is a perennial herbaceous plant that is propagated through both sexual and asexual means. It is native to the Himalayan region and is widely cultivated in many parts of the world.
Sexual Propagation
The plant can be propagated through seeds. The seeds should be sown in the spring or autumn in a well-drained soil that is rich in organic matter. The seeds can be directly sown into the ground or started indoors in pots and then transplanted outside after the last frost has passed. The seeds take about two to four weeks to germinate, and the seedlings can be transplanted about six to eight weeks after germination.
Asexual Propagation
The plant can also be propagated asexually through stem cuttings. The stem cuttings should be taken in the spring or autumn. The cutting should be about 6 to 8 inches long with at least one node. The lower leaves should be removed, and the cutting should be dipped in rooting hormone powder. The cutting can be planted in a well-drained soil that is moist and kept in a shaded area. The cutting will start rooting in about two to three weeks, and after a few months, it can be transplanted to its final location.
Another method of asexual propagation is by division. This is done by separating the plant into smaller sections and replanting them. This method should be done during the spring or autumn months. The plant should be carefully removed from the ground, and the roots should be washed. The plant can then be divided into smaller sections, with each section having at least one root and shoot. The divided sections can then be replanted in a well-drained soil that is rich in organic matter.
Disease and Pest Management for Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns
Like many other plants, Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns is susceptible to various diseases and pests. Here are some common problems encountered by growers of this plant and tips on how to manage them:
Diseases
One of the most common diseases that affect Lactuca glandulifera is downy mildew. It is usually caused by the fungus Bremia lactucae, which causes yellow spots and leaves that turn brown and die. To manage this disease, it is important to maintain proper spacing between plants. You can also treat the plants with a fungicide such as copper sulfate or a chemical compound like azoxystrobin. To prevent the spread of downy mildew, it is important to remove and properly dispose of infected plant debris.
Another common disease that affects this plant is powdery mildew. It is caused by a fungus (Erysiphales) that forms white powdery spots on the leaves and stems. To control powdery mildew, it is helpful to select resistant cultivars. Additionally, spraying the infected plant with a solution of baking soda and water or neem oil can also control the spread of powdery mildew.
Pests
The aphid (Aphis fabae), a small, soft-bodied insect, can cause great damage to Lactuca glandulifera plants. They feed on the sap of the plant, causing yellowing and stunted growth. To control aphids, frequent spraying of insecticidal soap or neem oil can be done. Insects that prey on aphids can also be introduced, like ladybugs.
Another pest that can affect Lactuca glandulifera is slugs and snails. They are attracted to the young foliage of plants and leave irregular holes as they feed on the leaves. To control slugs and snails, it is advisable to use physical barriers such as copper tape, diatomaceous earth, or eggshells around the plant. Alternatively, you can place beer traps near the affected plants to lure and trap them.
Overall, proper cultural practices and vigilance are essential in managing pests and diseases in Lactuca glandulifera Hook.f. var. calva (R.E.Fr.) Robyns. With timely interventions, the plant can easily overcome these problems and thrive optimally.
