The Castor Bean (Ricinus communis) is a semi-woody shrub or small tree, tropical and perennial, known for its applications in the chemical industry and biodiesel production, but it also features quite ornamental foliage, flowers, and fruits. The stem is singular, erect, and woody at its base, branching before the end of the first year of growth. Its leaves are glossy, alternate, palmate, deeply lobed, with toothed margins, supported by long and strong petioles.
In the typical form of the species, they emerge with reddish hues that gradually turn light green or dark green. The flowers appear in terminal inflorescences of the panicle type. The female flowers are generally green or reddish, without petals. The male flowers are yellowish-green, with cream-colored stamens. The fruits that form are globular capsules, each containing three seeds, covered with spines and can be green or reddish, depending on the cultivar. The dry capsules split into three parts, exposing and releasing the seeds.
There are many cultivars of Castor Bean, many of which are used for oil production. However, there are special varieties for ornamentation and landscaping, including ‘Carmencita’, with red and bronze leaves and red flowers; ‘Sanguineus’, with red branches and leaves; ‘Impala’, small in size with small leaves that turn purplish with age; ‘New Zealand Purple’, with a beautiful and deep purple hue of leaves and branches; ‘Gibsonii Mirabilis’, which is dwarf and has dark red leaves and branches; and ‘Zanzibarensis’, which is tall and has green leaves with white veins.
In landscaping, the Castor Bean is excellent for achieving a “tropical look” in the garden quickly and efficiently. Small groups or arrangements with other plants create a powerful effect. It is also an interesting plant for projects requiring quick, temporary, and impactful landscaping. Ideal for fairs and exhibition areas. In hot and humid climates, it can be used in long borders and as a backdrop for landscaping. In temperate climates, the Castor Bean is an excellent way to create a tropical effect around the pool or veranda during the warmer months.
The seeds of the Castor Bean contain a highly viscous oil that is easily soluble in alcohol, making it an ideal ingredient for biodiesel production. This oil also has various valuable applications in the chemical industry. They also contain a powerful toxin, ricin, which is lethal even in small doses.
It should be cultivated in full sun, in any type of soil enriched with organic matter and regularly irrigated in the first year of establishment. It is very easy to grow and grows at an astonishing rate, reaching tree size in just 4 months. It prefers tropical heat and humidity but can withstand a light frost. In temperate countries, it can be grown as an annual plant. It propagates by seeds, which are soaked for 24 hours in water before being sown in the spring.
