This section is from the book "Handbook Of Hardy Trees, Shrubs, And Herbaceous Plants", by W. Botting Hemsley. Also available from Amazon: Handbook of hardy trees, shrubs, and herbaceous plants.
Showy tuberous-rooted perennials with jointed stems, opposite simple leaves and showy flowers clustered towards the extremities of the branches. Perianth tubular or funnel-shaped. Stamens 5, cohering at the base in a ring, equalling or exceeding the perianth. About half a dozen species are known, natives of Central America and the West Indies. The name mirabilis, wonderful, was probably given to this genus because the Jalap of commerce was believed to be the product of M. Jalapa.
Fig. 207. Mirabilis Jalapa. (1/3 nat. size.)
1. M. Jalapa (fig. 207). Marvel of Peru.This familiar plant is treated as an annual. There are numerous varieties with white, yellow, crimson, or scarlet flowers, and others striped or blotched with two or more of these colours. West Indies.
M. longiflora, a Mexican species, is remarkable for its long tubular fragrant viscid flowers, which vary in colour from white and pink to violet. There are hybrid varieties between this and the preceding. M. dichotoma is called Four-o'clock Flower in the West Indies, from the time at which its flowera commonly expand.