Plant Description
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. is a perennial plant belonging to the family Fabaceae. It is commonly known as tree lupin, yellow bush lupin, or yellow tree lupin. The plant grows up to a height of 5 meters and has a woody stem with an upright branching habit. Its leaves are pinnate with 5-9 leaflets, and each leaflet is about 4-8 cm long. The plant produces tall spikes of yellow flowers that bloom in late spring to early summer.
Origin
The tree lupin is native to the coastlines of California and Oregon in the United States. It is also found in southwestern British Columbia in Canada. The plant was introduced to Europe in the 1820s as an ornamental plant, and it has since spread throughout parts of Europe, Africa, and South America.
Uses
The tree lupin is commonly grown as an ornamental plant in gardens and parks. The plant is especially attractive to bees, butterflies, and other pollinators. In addition to its ornamental value, the plant has also been used for erosion control, reclamation of mining sites, and as a source of food for livestock. The seeds of the tree lupin are edible and have been used by indigenous tribes in North America as a food source.
General Appearance
The tree lupin is an upright, woody plant with a branching habit. Its leaves are pinnate with 5-9 leaflets, and the plant produces tall spikes of yellow flowers. The plant produces a deep taproot, which allows it to grow in poor soil conditions and withstand drought. It is a hardy plant that can grow in a range of soil types, including sandy or loamy soils, and prefers full sun to partial shade.
Light Requirements
Lupinus arboreus Sims var. eximius is a sun-loving plant that requires at least six hours of direct sunlight per day. While it can tolerate some shade, it will grow best in a location that receives full sun.
Temperature Requirements
This plant is native to coastal Northern California, where it thrives in cool, moist conditions. It can tolerate temperatures as low as 20 degrees Fahrenheit, but it prefers temperatures between 50 and 70 degrees Fahrenheit.
Soil Requirements
Lupinus arboreus Sims var. eximius prefers well-drained soil that is rich in organic matter. It can tolerate a wide range of soil types, including sandy, loamy, and clay soils. The ideal pH range for this plant is between 6.0 and 7.5.
Cultivation methods
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. is an evergreen shrub that requires moist and well-draining soil. It prefers full sun to partial shade and can tolerate coastal conditions. It is best to plant it in the spring or fall after the last frost. The plant should be placed in a hole that is two times wider than the root ball. It is recommended to add organic matter to the soil before planting.
Watering needs
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. requires regular watering during the growing season. The soil should be kept moist but not waterlogged. It is important to avoid overwatering, as this can lead to root rot. It is best to water the plant deeply once a week rather than shallow watering more frequently.
Fertilization
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. does not require frequent fertilization. However, it may benefit from a slow-release, balanced fertilizer in the spring. It is important not to over-fertilize, as this can lead to excess growth and reduced flowering.
Pruning
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. requires minimal pruning. It may be necessary to prune back any dead or damaged branches in the late fall or early spring. Pruning can also help to shape the plant and encourage fuller growth. It is important not to prune too much, as this can reduce flowering for the following season.
Propagation of Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm.
Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. is a beautiful, evergreen shrub that is commonly found in coastal areas of California and Oregon. It is also known as tree lupin or yellow bush lupin. Propagation of this plant species is usually done through seeds as well as cuttings.
Propagation by Seeds
Seeds of Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. can be sown directly in the ground or in containers. To grow plants from seeds, they must first be soaked in water for 24 hours. This process softens the hard seed coat, making it easier for the seeds to germinate. After the seeds have soaked, they can be sown in well-draining soil. They should be sown at a depth of 1 inch, and spaced 12-18 inches apart. Germination usually takes place within 2-3 weeks.
Propagation by Cuttings
Cuttings can also be used to propagate Lupinus arboreus Sims var. eximius (Burtt-Davy) C.P. Sm. This method involves taking a cutting from a mature plant and allowing it to develop roots. To do this, take a 6-8 inch cutting from the plant, making sure it has several leaves. Remove the leaves from the lower half of the stem, leaving the top leaves intact. Dip the cut end in rooting hormone and plant it in well-draining soil. Keep the soil moist and provide partial shade. Once the cutting has rooted, it can be transplanted into a larger container or directly into the ground.
Disease Management
Lupinus arboreus Sims var. eximius can be susceptible to a variety of diseases, including powdery mildew, stem rust, and leaf spot. The following are some general practices that can help manage these diseases:
- Provide adequate spacing between plants to promote good air circulation
- Avoid overhead watering to reduce humidity levels
- Remove and dispose of infected plant material
- Apply fungicides labeled for use on lupines as directed
Common Pests
There are several pests that can cause damage to Lupinus arboreus Sims var. eximius, including:
- Aphids
- Spider mites
- Thrips
- Leafhoppers
Here are some methods for managing these pests:
- Use insecticidal soap or horticultural oils as directed
- Encourage beneficial insects, such as ladybugs and lacewings, which prey on pests
- Introduce predatory mites, which feed on spider mites
- Use yellow sticky traps to monitor and trap flying pests
As with any pest or disease management program, it is important to identify the specific problem before choosing a course of action. Consult with a local extension office or other plant expert for assistance in diagnosis and treatment.
