25 March 2018

Favourite Nectaring Plants #16

Butterflies' Favourite Nectaring Plants #16
The Peacock Flower (Caesalpinia pulcherrima)

In the 16th article in the series on our local butterflies' favourite nectaring plants, we feature an evergreen bush with attractively colourful flowers, the Peacock Flower (Caesalpinia pulcherrima). The Peacock Flower is often used in urban landscaping in Singapore and is a favourite amongst landscape architects looking to add colour to their palette of greenery and lush plants. It is also regularly cultivated in public parks and gardens.  

The Peacock Flower with its attractive flowers and pea pods

The Peacock Flower grows upright, attaining a height of 3-6 metres tall and a spread of 2-4 metres wide. The attractive shrub flowers throughout the year and usually does best in open areas in full sunshine. The orange-yellow flowers are pretty and uniquely shaped, with the stamens projecting well beyond the petals.  Although it is an exotic, it does not occur naturally and where it grows, it has been cultivated.

The genus name of this plant is in honour of the Italian physician, philosopher and botanist, Andrea Caesalpino. His most important publication, De plantis libri XVI (1583) is considered the first textbook of botany. He was the director of the Botanical Gardens at the University of Pisa. From 1592 he served as physician to Pope Clement VIII and taught at Sapienza University in Rome. The Latin species name pulcherrima means 'most beautiful', referring to the flowers.

The Peacock Flower is considered an exotic in Singapore. Its region of origin is the tropical Americas and was probably introduced to Singapore as a landscaping plant. Its use is limited to parks and gardens, usually cultivated an accent plant or as a boundary hedge. The brittle branches and sometimes thorny stems are considered negative attributes of cultivating the plant in urban gardens, and placing the plant adjacent to human traffic should be avoided.

Plant Biodata:
Family: Fabaceae (Leguminosae)
Genus : Caesalpinia
Species : pulcherrima
Synonyms : Poinciana pulcherrima
Country/Region of Origin : Tropical America
English Common Names : Peacock Flower, Barbados Flower Fence, Flower Fence, Cana, Barbados Pride, Red Bird of Paradise, Paradise Flower, Flamboyant Tree, Gold Mohur, Pride of Barbados, Dwarf Poinciana
Other Local Names : Jambul Merak, 金凤花, 洋凤花, 孔雀花

The bi-pinnate oval leaflets of the Peacock Flower and a young shoot

The Peacock Flower is a sprawling evergreen perennial shrub (or a small tree) reaching a maximum height of 6 metres, if left unpruned. Its deep green foliage is bi-pinnate, typical of Fabacea (Leguminosae) species. The leaves are fernlike and twice compound, with many small, oval leaflets.

The terminal racemes of the Peacock Flower, with the globular buds in a pagoda-shaped arrangement

The flowers are borne on terminal clusters of about 20-30cm tall. Each flower is bowl shaped, 2-3" across, with five crinkled, unequal red and orange petals, and ten prominent bright red stamens that extend way beyond the corolla. There is one modified petal which is smaller than the other 4 petals. The typical orange-yellow flower hybrid is the most common one cultivated in parks and gardens. However, there are other hybrids which feature all-yellow, pink-white and all-red flowers.

The pea pod is light green when immature, but turns a crispy chocolate brown when ripened

The fruits are oblong, with thin flat pods of up to 10 cm long and look like Snow Peas. The pods are light green when immature, turning to a dark brown when ripened. Each pod contains 8-10 flattened dark brown to black seeds which are ejected as the pod splits open at maturity.

A range of flower colours amongst the hybrids of the Peacock Flower

The Peacock Flower is only moderately attractive to butterflies, particularly the larger species. This may be because of the shape and design of the flower, which require longer proboscis of the larger butterflies to reach into the flower for nectar.

The very long stamens are a unique feature of the flower of this plant

In the field, there are occasions when no butterflies visit the flowers at all, especially when there are other preferred nectaring plants in the vicinity. However, on certain days and in the morning hours of the day, the flowers appear more attractive to butterflies and they will feed greedily at the flowers. Perhaps this could be due to the quantity of nectar produced by the flowers at specific times of the day? Or could there be some other explanation?

The larger Papilionidae feeding on the flowers of the Peacock Flower

Amongst the larger Papilionidae, the Common Birdwing, Great Mormon, Lime Butterfly, Common Mime and Common Mormon have been observed to feed on the flower of the Peacock Flower plant. We have not observed other species of the Papilionidae feeding on this plant's flowers.

Various Danainae feeding on the Peacock Flower.

The Danainae are sometimes attracted to the flowers of the Peacock Flower plant. Amongst these are the Common Tiger, Plain Tiger and Black Veined Tiger. On a single rare occasion, the extremely rare Mangrove Tree Nymph (Idea leuconoe chersonesia) was photographed feeding on the flowers of this plant at high level at Pulau Ubin's Butterfly Hill.

Some of the Pieridae also like the flowers of the Peacock Flower

Amongst the Pieridae, we have seen the Lemon Emigrant, Orange Emigrant and Mottled Emigrant attracted to feed on the flowers of the Peacock Flower plant. The Grass Yellows (Eurema spp.) are usually active around this plant, but more likely because it is one of their caterpillar host plants, and not to feed on the nectar from the flowers. There was one occasion when a Common Grass Yellow was observed to feed on the flower of this plant.

Thus far, there have been no observations of the other families of butterflies, particularly the smaller species, feeding on the flower of the Peacock Flower plant. Despite its attractive bright colours, it is strange that the Peacock Flower is not more attractive to a wider range of butterflies.

A male Great Mormon feeding on the flower of the Peacock Flower

Even though there is enough evidence to show that the Peacock Flower is a butterfly-attracting plant, the range of species that feed on its flowers is unfortunately rather limited. In the selection of nectaring plants for a butterfly garden, it would be probably wise to combine several other more preferred nectaring plants with the Peacock Flower to offer a wider range of nectaring plants to attract more species of butterflies.

Text by Khew SK : Photos by Bob Cheong, Huang CJ, Khew SK, Loh MY and Simon Sng.