Kosi palm (Raphia australis)


Kingfisher Lake

Raphia australis

Doesn’t the name Raphia sound familiar? The generic name is likely derived from rofia, the Magalasy vernacular name for a related species, R. farinifera, which eventually lent its name to raffia string or twine. These fibres are stripped from the fronds and can also be made into rope and tree-grafting material, as well as dyed and woven into mats, baskets, hats, and shoes!  In addition to the raffia fibres, the petiole and rachis of Raphia palms are also used for construction and furniture materials, and the sweet sap from tapping the developing inflorescence (flower stalk) fermented into a palm wine.

Endemic to a small area from the Gaza province in southern Mozambique and part of the KwaZulu-Natal province in South Africa, the Kosi palm (Raphia australis) is named after its occurrence within Kosi Bay, a series of four interconnected lakes within KwaZulu-Natal province. 

The Kosi palm can reach a height of 16 metres The Kosi palm can reach a height of 16 metres with fronds up to 10 metres long! — but not as long as its cool-growing cousin, R. regalis, boasting a record-breaking length of 25 metres, making it the plant with the longest leaves in the world!

Because of its specific epithet, it’s no surprise that many might mistake this species to be native to Australia. The name australis is Latin for ‘from the South’, referring to this species being the southernmost representative of its genus. In fact, Australia got its name from the term Terra Australis (meaning ‘southern land’), which was a name for a hypothetical continent in the Southern Hemisphere during ancient times and was later applied to the continent by English explorer Matthew Flinders in the 19th century.

The orange-brown developing inflorescence of the Kosi palm can reach 3.6 metres in height! Growing from the centre of its crown, the orange-brown developing inflorescence of the Kosi palm can eventually reach 3.6 metres in height!

An exciting moment for botanical enthusiasts, the flowering event for the Kosi palm is but a once-in-a-lifetime occasion for the palm. This palm species is hapaxanthic in nature, meaning that it will soon perish after it has completed flowering and fruiting, a process that can take several years! This happens because the single, terminal bud of the palm (commonly referred to as the ‘heart’ or ‘bud’)  produces leaves, but once the palm transitions into reproductive mode, this bud terminates in producing the inflorescence or flower stalk, preventing the palm from resuming vegetative growth after flowering and fruiting.

As tragic as this may seem, this reproductive strategy ensures that each individual palm can efficiently produce thousands of flowers and fruits from all its accumulated resources within the stem of the palm when the conditions are favourable. Other palm species that follow this strategy include the majestic talipot palms (Corypha umbraculifera) and the Tahina palm (Tahina spectabilis) within Supertree Grove, as well as the buri palms (Corypha utan) in Golden Garden.

Covered in shiny, brown scales, the large, ovular fruits of the Kosi palm are 6-9cm long, with a single large seed within, and may take at least 1-2 years to fully mature. These seeds are dispersed by the unique palm nut vulture, (Gypohierax angolensis), an unmistakable, large white-and-black Old-World vulture with distinctive red or orange eye patches, native to Africa. Unusual for a vulture, about 70% of its diet consists of palm fruits, from the Kosi palm and other Raphia palm species, as well as oil palm and date palm. The colour of the bare skin of the bird’s eyepatch comes from the orange or red carotenoid pigments from the palm fruits themselves!

While there are 26 species in the genus Raphia, only two can be found here in Gardens by the Bay: While there are 26 species in the genus Raphia, only two are found at Gardens by the Bay: the Kosi palm, R. australis (background; right) and R. farinifera (foreground; left); found opposite each other on the banks of Kingfisher Lake.

Our flowering specimen can be found near the water’s edge of Kingfisher Lake behind the Children’s Garden; this wet environment mimics the natural habitat of swamps, peat bogs, and seasonally inundated dunes in its native distribution.

Fret not if you’re not in town; the palm will be in flower for the next few months. So come on down and marvel at this cryptic wonder of nature!

Written by: Hazri Boey, Senior Horticulturist (Gardens Operations)

Hazri not only surrounds himself with plants at work; he has an abundant collection at home too! Having nurtured a keen interest in nature since young, he might have gone on to become a zookeeper caring for owls or sloths had it not been for his plant identification talent!

This article is part of our What's Blooming series.