Mirabilis species: Four o'clock

Family

Nyctaginaceae

Common Name

Four o’clocks, Marvel of Peru, umbrellawort (Mirabilis jalapa)

Plant Description

Consisting of about 50 - 60 species native to Central and South America, Mirabilis are annuals or perennial herbaceous plants arising from fleshy or woody roots.

Depending on the species, the branching plants may reach heights of 100 cm, and have dark green, opposite, ovate to cordate, petiolate to sessile leaves. Flowers are produced terminally, and are funnelform, in a variety of colors, and opening in the late afternoon (Fig. 271 and Fig. 272). The fruits are 5 sided achenes.

Figure 271. Mirabilis jalapa.

Figure 272. Mirabilis jalapa.

Toxic Principle and Mechanism of Action

The seeds and roots contain the alkaloid trigonelline which is an irritant to the skin and the digestive tracts.

Risk Assessment

The only reported cases of poisoning have involved the common four o’clock (M. jalapa) [1]. This common garden plant is a prolific seed producer and can therefore be a potential source of the toxic seeds for children or pets.

Clinical Signs

Chewed seeds if swallowed can cause vomiting and diarrhea.