Solenostemon species: Coleus

Family

Lamiaceae

Common Names

Coleus, variegated coleus.

Plant Description

A genus of some 60 species of shrubby perennials, Solenostemon are native to tropical Africa and Asia. The stems are square (4-angled), and the leaves opposite, toothed, and variegated in colors ranging from yellow, red, pink, to purple (Fig. 369 and Fig. 370). Inflorescences are terminal racemes or panicles, the flowers in whorls. Individual flowers are small, blue to purple in color with an elongated lower lip. Fruits are nutlets enclosed in a papery calyx.

Figure 369. Solenostemon scutellarioides cultivars.

Figure 370. Solenostemon scutellarioides.

Toxic Principle and Mechanism of Action

A volatile oil, coleon O, has been isolated from the leaves and has allergenic properties [1,2]. Coleus is listed as a potentially toxic plant by the National Animal Poison Control Center capable of causing vomiting, diarrhea, depression, anorexia, and in severe cases, hemorrhagic vomiting and diarrhea [3].

Risk Assessment

Coleus are common tropical plants and are frequently planted as summer annuals in temperate areas for their colorful variegated leaves. They are also popular potted house plants. As such, they pose a potential hazard for household pets, but no known cases of poisoning in animals have been reported. Some people are prone to developing a contact dermatitis when handling the plants frequently [2].

Clinical Signs

Vomiting, diarrhea, depression, anorexia, and in severe cases, hemorrhagic vomiting and diarrhea are the main clinical signs that can be anticipated [3]. When necessary, symptomatic treatment should be provided.