Cestrum

Cestrum diurnum

Cestrum parqui

Cestrum is a genus of flowering plants in the family Solanaceae, which is known for its diverse species of shrubs and small trees. The genus is native primarily to the Americas, with its distribution ranging from the southern United States through to South America. Cestrum species are characterized by their lance-shaped leaves, tubular flowers, and often brightly colored berries. These plants are notable for their ornamental value and some species are widely cultivated in gardens and landscapes around the world.

Description

Cestrum species vary in size from small shrubs to larger tree-like plants. They possess simple, alternate leaves that can be either evergreen or deciduous depending on the species and the climate in which they are grown. The flowers of Cestrum plants are typically small, tubular, and clustered in terminal or axillary inflorescences. These flowers can be highly fragrant, especially at night, which attracts a variety of pollinators including moths and bees. Following pollination, many species produce colorful berries that can range in color from red to black, adding to their ornamental appeal.

Ecology

Cestrum species play a significant role in their native habitats. The nectar-rich flowers serve as an important food source for pollinators, while the berries are eaten by various species of birds and mammals, aiding in seed dispersal. However, it is important to note that many parts of Cestrum plants, particularly the leaves and berries, contain toxic compounds that can be harmful if ingested by humans or domestic animals.

Cultivation

Cestrum is popular in horticulture for its attractive flowers and berries, as well as its ability to adapt to a variety of growing conditions. These plants can be grown in full sun to partial shade and require well-drained soil. While they are relatively drought-tolerant once established, regular watering during dry periods can promote healthier growth and flowering. Pruning is often necessary to maintain the desired shape and size, as well as to encourage more prolific blooming.

Species

There are over 250 species in the Cestrum genus, including:

• Cestrum nocturnum, commonly known as night-blooming jasmine or lady of the night, is renowned for its intensely fragrant white flowers that open at night.
• Cestrum diurnum, also known as day-blooming jasmine, contrasts with C. nocturnum by opening its less fragrant white flowers during the day.
• Cestrum parqui, known as green cestrum or willow-leaved jessamine, is notable for its greenish-yellow flowers and is considered invasive in some regions.

Toxicity

Many Cestrum species contain toxic alkaloids, particularly solanine, which can cause symptoms ranging from mild gastrointestinal distress to more severe neurological effects if ingested. The level of toxicity varies among species and parts of the plant, with the berries generally being the most toxic. It is important for gardeners and pet owners to be aware of the potential risks and to keep these plants out of reach of children and animals.

Conservation

While many Cestrum species are common and not considered at risk, habitat destruction and overcollection have put some species at risk of extinction. Conservation efforts are necessary to ensure the survival of these species in their native habitats.