Frangipani
Plumeria rubra is one of the best-known, and most widely cultivated, Plumeria species. It is memorable for the large flowers, with their strong, sweet scent, that conjures warm, tropical visions whenever the smell is noticed. Visitors to Hawaii, where the plant is not native but cultivated, will be greeted with a lei, a strung necklace of Plumeria flowers, placed around the neck. This ritual has become such a popular practice that Plumeria flowers are now a significant crop in Hawaii; at least 14 million flowers are harvested annually for use in leis. Other uses of Plumeria flowers are as national flowers in Nicaragua, Sicily and Laos, and as religious offerings in parts of Asia.
The name Plumeria commemorates the French botanist and Franciscan monk Charles Plumier (1646-1704), who travelled to the West Indies three times during the seventeenth century. During these visits he studied and drew many of the plants he found there.
Plumeria is a small genus that is native to tropical America, from Mexico through Central America to northern South America. It consists of small- to medium-sized deciduous trees and shrubs with thick stems and leaves clustered at the ends of sparse branches. The flowers appear in clusters at the end of the branches. The tubular flowers open with the upper lobes of the petals spreading out but slightly overlapping. Despite the specific name, Plumeria rubra flowers are usually white, or white tinged with various shades of pink, with yellow centres. Because the plants are not hardy they are grown as house plants or in conservatories in temperate regions. In the UK a few cultivars are available which flower from July to October. The stems exude a milky juice when cut which can be an irritant and is somewhat poisonous.
The pollination of Plumeria flowers is about deception. Plumeria flowers do not produce nectar, which is often a reward for pollinators, instead they appear to have evolved visual clues and scents that dupe its pollinators. The large, tubular flowers, which are produced in large numbers, are often white and strongly scented at night when hawkmoths are active.
In Costa Rican deciduous forests, Plumeria rubra leaves are the food for the larvae of the frangipani sphinx moth (Pseudosphinx tetrio). The larvae themselves mimic coral snakes being black with bright yellow stripes and orange heads, and bite ferociously when touched, which may protect the Plumeria flowers from unwelcome destructive visitors.
Further reading
Haber WA 1984. Pollination by deceit in a mass-flowering tropical tree Plumeria rubra L. (Apocynaceae). Biotropica 16: 269-275.
Janzen DH 1983. Pseudosphinx tetrio (oruga falso-coral, frangipani sphinx). In: Janzen DH Costa Rican Natural History. University of Chicago Press, pp. 764-765.
Woodson Jr. RE 1938. An evaluation of the genera Plumeria L. and Himatanthus Willd. Annals of the Missouri Botanical Garden 25: 189-224.
Serena Marner