| Eugeissona | |
|---|---|
 | |
| Eugeissona utilis | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Monocots |
| Clade: | Commelinids |
| Order: | Arecales |
| Family: | Arecaceae |
| Subfamily: | Calamoideae |
| Tribe: | Eugeissoneae |
| Genus: | Eugeissona Griff.[1] |
| Species | |
Eugeissona is a clusteringgenus offlowering plant in thepalm family native toBorneo,Thailand andMalaysia. The sixmonoeciousspecies provide a wide range of local uses and are commonly calledbertam orwild Bornean sago. The genus is the sole representative of theEugeissoninae having very few obvious relatives; thehermaphrodite and staminate flowers are also found inMetroxylon, however the other specialized characteristics are unique suggesting an early split and differentiation from other members of theCalameae.[2] Fossilizedpollen belonging to these plants has been recovered in the lower and middleMiocene deposits inSarawak.[2] The name is from twoGreek words meaning "good" and "roof", due to their common use in roofthatching.
All of theEugeissona palms will form above-ground stems where the apical inflorescence will appear toward the final year of the palm life. For the highland natives of Borneo they let theE. utilis palm grow trunk and harvest it just before flowering for its palm heart and the starch (sago) found inside.[3] Amongst the lowland native, the much sought-after palm heart is harvested before the trunk has been formed. During trunk-forming they are supported by tall masses of stilt roots in which detritus and leaf matter collect, providing nesting to various biota. The large leaves are carried on long, spiny petioles, and the rachises and trunks are also spine-bearing. The erect inflorescence bears some of the largest flowers in the palm family, emerging within the leaf crown featuring both male and bisexual flowers. The fruit is a beaked, ovoid drupe carrying one seed.[4]
Eugeissona tristis, from West Malaysia, is adapted to promote microbial growth in its flowers. It bears robust, long-lived (sometimes over 4 months) flowers which contain abundant yeast populations. In the central chambers of these flowers, yeast fermentation generates a nectar that is almost 4% ethanol. The palm is pollinated by mammals (squirrels, nocturnalmurids, and treeshews like thepentailed treeshrew) which have adapted to chronic alcohol consumption.[5]
They inhabit a variety of settings including the low-lyingheath forests,montanerain forests, andswamps, but are most common onscarp faces, hills and rocky ridgetops up to 1000 m.E. brachystachys andE. tristis are found solely in Malaysia, while the remainder are Bornean or Thai in origin.E. tristis has become an effective pest in the Hill Dipterocarp forest where it colonizes cleared timberland preventing the regeneration of various trees.
While not common in cultivation, they are used extensively by locals for a variety of purposes. Thesago made fromE. utilis trunks forms the staple of thePenan andPunan diet. The seed'sendosperm and the pollen are also known to be consumed. The leaves are used in roof construction, various thatchings, and the manufacture of blinds. The stilt roots of some species are made into walking sticks and toys, while thepetioles are fashioned intodarts forblowgun hunting.[2]
