Pterocymbium oceanicum

Also known as: Local Names: Yanita, Anita, Ma

Description

The Yanita, or Ma is a beautiful tall tree that can grow from 15-40m in height stem size(DBH) ranging from 50cm-200cm. It does not have many branches, with most of the branches crowding at the top of the tree. While the trees appear white in color from a distance, close up the tree’s bark is a light shade of grey  with mosaic blots of white, yellow, brown and green irregularly dispersed on the tree bark.

The leaves are cordate in shape and are bunched together in a spiral formation at the tips of branches. Young leaves are light green in colour and dark green at maturity and fade to yellow . Trees have been observed to show deciduous behavior where some trees shed leaves before flowering.

Flowers are bunched in clusters and are bell shaped, 2cm in size, 5-lobed, pubescent on the outer surface and glabours on the inner surface.

Fruits are attached to the base of a winged boot follicle, up to 5 follicles protrude hanging from the parent flower in a whorled formation. Follicles are papery to touch, pubescent on the outer surface and glabours on the inner surface, follicle color is greenish yellow in colour with blots of red.

Distribution

Yanita is endemic to Fiji, and has only been recorded from northwestern Viti Levu (in the Nausori Highlands) and from the east-central Vanua Levu.

Habitat Ecology and Behaviour

This species is a dominant, emergent tree in the dry forests of Fiji. The Yanita population in the Abaca range has been observed bearing flowers from June to September; sterile trees have been observed in November, February and August. No fruits have been seen from the Abaca population. Feeding activity has been observed around flowering trees at the Abaca population: bees, Wattled honeyeater (Foulehaio procerior) and the collared lory (Phigys solitarius) have been observed to be feeding on nectar during the flowering season.

The Yanita population at the Navakuru site has been noted to flower from March to April and begins to fruit from May. Fruits are noted within a 6-7m radius of the parent tree. The members of the genus Pterocymbium are known to be monoecious trees. Thanks to a grant from Botanic Gardens Conservation International and Fondation Franklinia, NatureFiji-MareqetiViti has a grant to document the habit and ecology of this species.

There is not much else known of this endemic plant. The members of the genus Pterocymbium are known to be monoecious trees.

Threats

Because this is a species that is found in the transition between the dry forest and rain forest in Fiji called the “mesic zone” (Keppel et al., 2006), it has probably disappeared with the conversion of Fiji’s dry forest to agriculture, mainly sugar cane, and grasslands through repeated burning.

Conservation Status

Until 2019, the remaining populations and their distribution were poorly known. Not so long ago this species was sufficiently common to enable many of the wooden bridges along the King’s highway, in the Wainibuka area to be made of timber from the Yanita. This species was heavily exploited in both Koroyanitu (Mt. Evans range) and the Nausori highlands – in the dry side of Fiji.

The Yanita was included in the IUCN Red List of threatened species in 2016 as Critically Endangered A2cd (Rivers 2016), and it is listed in the Fiji Endangered and Protected Species Act (Act 10 of 2017) under Schedule 1 – this was possible through an assessment that was conducted by NatureFiji-MareqetiViti in collaboration with Botanic Gardens Conservation International, Global Trees Campaign and the Franklinia Fondation.

Since 2019, Botanic Gardens Conservation International and the Franklinia Fondation have been supporting NatureFiji-MareqetiViti to confirm the status of the populations, study its phenology, develop propagation methods, and develop a species recovery plan. This project is on-going, and the species recovery plan will be published in December 2021.

Remarks and Cultural Significance

Remaining populations and their distribution are very poorly known. However, not so long ago this species was sufficiently common to enable many of the wooden bridges along the King’s highway, in the Wainibuka area to be made of timber from the Yanita. This species was heavily exploited in both Koroyanitu (Mt. Evans range) and the Nausori highlands in the dry side of Fiji.

References

Alston, A. S. 1982. Timbers of Fiji: Properties and Potential Users. Department of Forestry, Suva.

Keppel, G., Isaac, Rounds, I.A. and Thomas, N. 2006. The flora, vegetation, and conservation value of mesic forest at Dogotuki, Vanua Levu, Fiji Islands. New Zealand Journal of Botany 44(3): 272-293.

Rivers, M.C. 2016. Pterocymbium oceanicum. The IUCN Red List of Threatened Species 2016: e.T99752101A99752113. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T99752101A99752113.en. Downloaded on 22 March 2021

Smith, A. C. 1981. Flora Vitiensis Nova: A New Flora of Fiji (Spermatophytes only) Volume 2. Pacific Tropical Botanical Garden, Kauai

Tuiwawa, M. personal communication.

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