Is this the time to collect the Chin of Prometheus?

When German botanist Joachim Shiermeyer came to Dokmai Garden in February he was well prepared with a list of ‘want to see’ downloaded from our species list. His ongoing quest is to photograph representatives of all plant families in the world.

One Dokmai Garden tree from which he collected seeds was Irvingia malayana (Irvingiaceae) which grows behind the Dokmai Garden laboratory. Some Thai names are ‘gabok’, ‘ma luen’, ‘lak kai’, ‘cha ang’ and here in the north ‘muen’. At this time of the year, I often believe I hear somebody knocking on the door, but it is just the heavy fruits falling down on the roof.

Here are two fresh fruits and two fibrous yellow stones which have been cut to expose the white oily seed. In the middle a brown stone from a decaying fruit.

The fruit contains one large seed and I knew that Nived Seehamongkol likes to roast such seeds and eat them like almonds. I gathered a handsome bunch and proudly gave them to Nived. She smiled and said they are too fresh and so very difficult to open. Normally they are collected in February-March when the pulp is gone and the kernels are dry. The kernels are then simply roasted on charcoal. With great effort she used a butcher’s knife to open a fresh seed to show me.

I asked if they ever ate the pulp of the fresh drupe, but she said the fruits are either too hard or too dirty from fermenting on the ground. It is true they remain hard in the tree and only soften on the ground, where the pulp turns soft and juicy with an appealing plum flavour (I did taste them). The seeds seem tricky to germinate. The tree behind the lab has produced thousands of fruits over the years but not a single seedling in spite of a range of nearby habitats. I have also failed to germinate the seeds in pots, but I used seeds collected in February, also from fire-damaged areas. This is in accordance with germination efforts of African Irvingia species and Kew Gardens include Irvingia in the ‘Difficult Seeds Project’. Maybe the seeds need to pass through the guts of a mammal now in August-September to soften and germinate while it is still wet? Seeds left to dry for six months may never soften enough to open and may succumb to fungi or fire?

The trees may grow into majestic proportions according to Ketsanee. I have seen many trees scattered in the nearby national park, but since most big specimens of most of the local 1100 tree species have been logged we have to wait a millennium for the forests to fully recover from the extensive logging in 1880-1988. Flora of Thailand 2:398 claims the wood is not durable and so the wood of this species has been used for making charcoal. That is surprising since African Irvingia species are reportedly durable and termite-resistant. Irvingia malayana is native to the Asian lowlands and can be found in both dry monsoon forests in India, Burma, Laos and Thailand and in the rainforests of Sumatra and Borneo.

 

So, what is this strange family, Irvingiaceae (sometimes included in the families Ixonanthaceae or Simaroubaceae)? There are only about ten species and three genera in the world, all native to the old world tropics. A character in common is the long horn-like stipule which encircles the leaf bud. As to the genus Irvingia, only one species is recorded from Asia, and the other five grow in Africa. The most famous might be Irvingia gabonensis which kernels are used for making ‘gabon chocolate’ or more precisely ‘odika’ or ‘dika bread’. 

The genus name was coined by the Scottish botanist Sir William Jackson Hooker (1785-1865) when he described Irvingia smithii from west Africa in 1860. The name alludes to the Scottish plant collector and navy surgeon Edward George Irving (1816-1855) who collected plants in southern Nigeria while serving on the HMS Prometheus.

At this time of the year, the tree-borne fruits are green and hard and may resemble a lot of other jungle fruits. Some newcomers even think they are small green mangoes and an unfortunate English vernacular name is ‘African mango’ for Irvingia gabonensis. The tip of the fruit resembles a cleft chin, which separates this species from many look-alikes.

An English name? ‘Wild almond’ has been used but since this tree has nothing to do with almonds it is a name as confusing as ‘African mango’ for its African sister. Although the scientific name is its real and precise international name, English names may create an appreciation for the tropical flora outside the sphere of specialists. Therefore this darling deserves a unique and catchy name to show there are more plant treasures in the world than mango and almond. ‘Asian Irvingia’ is obvious but does not add much to the scientific name and remains uncatchy. How about ‘Chin of Prometheus’, alluding to the tree’s mature size (Prometheus was one of the titans), to its (and Prometheus’) friendship with humans, to its (and Prometheus’) association with fire, to Irving’s ship and to the characteristic cleft of the fruit?

Text & Photo: Eric Danell