Plant Formations in the Sumatran BioProvince - Terrestrial Biozones

Plant Formations in the Sumatran BioProvince 

Copyright © 2010 Peter Martin Rhind 

Peter Martin Rhind 

Sumatran Lowland Dipterocarp Forest 

These luxuriant forests are some of the most diverse on Earth with comparable levels of 

species diversity to the richest forests in Borneo and New Guinea and comprise over 100 

species of dipterocarps, six of which are endemic. Some of the mature parts can have up 

to four distinct tree stories as well as shrub and herbaceous layers. The emergent trees, 

which can reach heights of 60 m, are mainly dominated by dipterocarps such as 

Anisoptera costata, Dipterocarpus crinitus, Hopea dryobalanoides, Parashorea lucida and 

Shorea macrocarpa. Other important upper canopy trees are Dyera costulata, Fragraea 

gigantea, Koompassia malaccensis, Mangifera rigida, Myristica gigantea, Polyathia 

hypoleuca and the endemic Heritiera sumatrana (Sterculiaceae), Horsfieldia triandra 

(Myristicaceae) and Polyalthia sumatrana (Annonaceae). Among the many trees of the 

sub-canopy are Aporusa elmeri, Dacryodes rugosa, Diospyros buxifolia, Diplospora 

singularis, Drypetes longifolia, Gironniera hirta, Nephelium cuspidatum, Timonius 

hydrangefolius and Xanthophyllum elmeri, while smaller trees of up to 15 m include an 

abundance of Aglaia tomentosa, Aporosa frutiscens, Baccaurea javonica, Croton 

oblongus, Fordia johorensis and Koilodepas glanduligerum. The endemic small tree 

Baccaurea sumatrana (Euphorbiaceae) like many other trees of these forests produces 

flowers and fruit at the base of its trunk - a phenomenon known as cauliflory. Other 

endemic small trees are Casearia cuspidata (Flacourtiaceae), Daphniphyllum 

sumatraense (Daphniphyllaceae), Diplycosia apiculifera (Ericaceae) and Gomphandra 

fusiformis (Icacinaceae). 

In the undergrowth shrubs such as Agrostistachys longifolia, Gonocaryum gracile, 

Psychotria robusta and Rinorea anguifera are common as is the small tree fern Cyathea 

moluccana and palms like Licuala ferruginea and Pinanga malaiana. Endemic shrubs 

include Arthrophyllum papyraceum (Araliaceae), Clethra sumatrana (Clethraceae), Saraca 

tubiflora (Fabaceae) and Thottea reniloba (Aristolochiaceae). Lianas and climbers are 

common especially climbing palms mostly represented by rattans like Calamus flabellatus, 

Daemonorops depressiuscula and Korthalsia rigida, while other climbing species include 

Agelaea macrophylla, Fissistigma kentii, Hugonia costata, Salacia macrophylla, 

Sarcostigma paniculata, Smilax leucophylla, Uncaria calophylla, Willughbeia firma and 

endemic Aristolochia singalangensis (Aristolochiaceae) and Erycibe ramiflora 

(Convolvulaceae). On the ground some of the most common species are Hanguana 

malayana, Labisia pumila, several orchids such as Cystorchis saceosepala and ferns like 

Lindsaea doryphora. These forests are also famously know as habitat for the plant with the 

world’s largest flower (Rafflesia arnoldii), which is a parasite of the vine Tetrastigma, and 

the plant with the world’s tallest flowers, the endemic Amorphophallus titanium (Araceae). 

This magnificent arum has flowers up to 2 m tall and produces a fetid odor that attracts 

small bees that act as pollinators. 

Sumatran Riparian Forest 

These forests, confined to riverbanks, undergo temporary flooding during heavy rain. They 

show considerable floristic diversity and vary according to location and flooding regime. On 

the west coast the enormous Canarium pseudodecumanum is often the dominant 

emergent species reaching heights of up to 50 m, while the main canopy trees, at heights 

of 25 m, include Antiaris toxicaria, Blumeodendron kursii, Dracontomelon dae, Pometia 

pinnata, Pterospermum javanicum, Santiria apiculata and the endemic Neoscortechinia 

sumatrensis (Euphorbiaceae). In southern areas other species may dominate including

Alstonia spathulata, Canthium dicoccum, Dillenia excelsa, Ficus retusa, Gluta renghas, 

Kayea ferruginea, Koompassia excelsa, Myristica elliptica, Neesia malayana and several 

endemic species like Mangifera gedeba (Anacardiaceae), Shorea sumatrana and Vatica 

venulosa (Dipterocardiaceae). 

Sumatran Swamp Forest 

These forests occur in areas that are periodically flooded for relatively long periods of up to 

four months or more, and their floristic composition varies according to factors such as 

frequency and duration of flooding. As a result they are much more varied than forests of 

well-drained ground. In east Sumatra the main canopy trees are Artocarpus kemando, 

Baccaurea bracteata, Blumeodendron tokbrai, Campnospermum auriculatum, Mangifera 

paludosa and Parartocarpus venenosus. These can reach heights of up the 25 m or so, 

but often towering above these are various emergents like Alstonia pneumatophora and 

several dipterocarps such as Dipterocarpus apterus and Shorea balangeran that can 

reach 50 m or more. Among the associated endemic trees are Casearia gigantifolia 

(Flacourtiaceae) and Vatica teysmanniana (Dipterocarpaceae). In the undergrowth palms 

like Eleiodoxa conferta, Licuala spinosa, Oncosperma tigillarum are common as are 

various rattans such as Calamus caesius, Daemonorops geniculata and Korthalsia 

flagellaris. Shrubs may be present including the endemic Erycibe sumatrensis 

(Convolvulaceae). Ferns are also characteristic and besides Stenochlaena palustris, a 

climbing species with edible shoots, there are species such as Mesophlebion 

chlamydophorum, Microsorum musifolium, Paragramma longifolia, Pyrrosia lanceolata, 

Vittaria elongata, and in more open areas tree ferns like Cyathea contaminan. At ground 

level, not surprisingly, members of the Cyperaceae are common and may include 

Thoracostachyum bancanum and the endemic Scleria sumatrensis. 

Sumatran Peat Swamp Forest 

Mainly confined to the east coast at the central and southern parts of the island, these 

forests are particularly abundant from the Musi delta to the Siak River. The peat deposits 

are usually about 50 cm deep but can be up to 20 m in places, and as a result of the low 

nutrient status and high acidity of these soils their floras are not as species-rich or as rich 

in endemics as other forests. Their floristic composition varies from place to place, but in 

southern Sumatra the most representative canopy trees are Campnospermum coriaceum, 

Durio carinatus, Mezzettia leptopoda, Santiria laevigata, Tetramerista glabra and Xylopia 

fusca. These reach heights of 35 m, but exceeding these by a further 15 m or so are 

various emergents like Dyera lowii and Shorea teijsmanniana. Among the many smaller, 

sub-canopy trees are Blumeodendron tokbrai, Combretocarpus rotundatus, Parastemon 

urophyllus, Tetractomia obovata, the endemic Neoscortechinia sumatrensis 

(Euphorbiaceae) and numerous species of Diospyros. The few palms include the 

emergent Livistonia hasseltii and the bright-red sealing wax palm Cyrtostachys lakka. 

Shrubs in the undergrowth are mostly Antidesmus montanum, Dacryodes rostrata, 

Eugenia setosa, Goniothalamus malayanus, Ixora malayana and Memecylon oligoneura. 

However, the flora that is specific to peat swamps is very limited, but includes, for 

example, the endemic dipterocarp Vatica teijmanniana (Dipterocarpaceae). Some of these 

peat swamp forests are described as pole forests because of the dominance of long 

straight trees. 

Sumatran Hill Forest 

In certain places, such as the Barisan Hills, the forest between altitudes of about 150-500 

m has a different species composition from lowland forests. They are still classed as 

dipterocarp forests and have canopies reaching 40 m or so. The emergent species reach 

heights of 55 m and typically include Shorea bracteolate, S. gibbosa and S. hopefolia, 

Copyright © 2010 Peter Martin Rhind

while the canopy may include Albizia spendens, Alstonia scholaris, Artocarpus 

anisophyllus, Magnolia elegans, Whitfordiodendron atropurpurea and the endemic 

Parashorea aptera (Dipterocarpaceae). The middle and lower tiers show the appearance 

or greater abundance of Aidia cochinchinensis, Chisocheton patens, Crypteronia griffithii, 

Ctenolophon parvifolius, Diospyros lanceifolia, Gymnacranthera farquhariana, Horsfieldia 

polyspherula, Kitabalia maingayi, Pellacalyx lobbii and the endemic Knema lampongensis 

(Myristicaceae). Other endemic trees include Knema sumatrana (Myristicaceae), Shorea 

conica and Vatica obovata (Dipterocarpaceae). At ground level, the steep slopes are one 

of the favourite habitats of Rafflesiaceae. Species include Rafflesia arnoldi, the endemic R. 

gadutensis and the more modest but just as fascinating Rhizanthes zippelii. 

Sumatran Submontane Forest 

These forests range in altitude from about 800 to 1400 m and can be just as majestic as 

the lowland forests with emergent trees reaching heights of 50 m or so, and many of the 

trees have large buttresses. This is despite the fact that dipterocarps are far less common 

and is largely superseded in terms of dominance by the Clusiaceae, Euphorbiaceae, 

Fagaceae and Myrtaceae. Lauraceae, on the other hand, which you would expect to be 

one of the dominant families of these forests, is not as prominent on Sumatra. The 

characteristic upper canopy and emergent species include Altingia excelsa, Drypetes 

minahassae, Lithocarpus hystrix, Neesia altissima, Parkia singularis, Podocarpus 

imbricatus, Quercus oidocarpa, Santiria laevigata, Sarcosperma paniculatum, Shorea 

platyclados and Toona sinensis. There are also numerous strangling figs such as Ficus 

distica and F. elastica. In the sub-canopy between heights of 25 to 30 m the Fagaceae 

and Myrtaceae become even more pronounced with species such as Castanopsis 

tungurrut, Lithocarpus elegans, Quercus longiflora and at least 20 species of Eugenia - 

species from other families include Casearia tuberculata, Chionanthus exycarpus, 

Cryptocarya ferrea, Dacrydium elatum, Engelhardtia serrata, Radermachera pinnata, 

Talauma candolei, Terminalia myriocarpa and endemics like Michelia salicifolia 

(Magnoliaceae) and Trevesia arborea (Araliaceae). Smaller trees and shrubs include 

Ardisia blumii, Bennettiodendron leprosipes, Canthium horridum, Diospyros 

subrhomboides, Ellipanthus tomentosus, Garcinia urophylla, Symplocos fasciculate and a 

number of endemics such as Dehaasia sumatrana, Gomphandra fusiformis (Lauraceae) 

and Vaccinium gracilipes (Ericaceae). Tree ferns are locally abundant but mainly 

represented by Cyathea hymenoides and the endemic Cyathea alderwereltii 

(Cyatheaceae). Most of the lanoid species are similar to those of lowland forests, but 

Chilocarpus costatus, Tetrastigma lanceolata, Uncaria elliptica and Ziziphus horsfieldii 

appear to be characteristic of the sub-montane zones. Characteristic ground layer species 

are Crytandra pilosa, Gomphostemma microcalyx, Pleomele angustifolia, Phrynium 

capitatum and Sarcandra glabra. Grasses are rare but may include Oplismenus 

compositus. Among the endemic herbaceous flora is Gomphostemma dolichobotrys 

(Lamiaceae). 

Sumatran Montane Forest 

These forests occur between altitudes of about 1400 and 1900 m and can be seen, for 

example, on Mount Kerinei (Sumatra’s highest mountain), and an active volcano. They 

usually consist of two tree layers - the canopy that reaches heights of 30 m and a subcanopy 

between 10 and 20 m. Below this is a shrub layer ranging in height from 5 to 10 m. 

Fagaceae (including Lithocarpus pallidus and Quercus gemelliflora), Lauraceae (including 

Litsea tuberculata), Myrtaceae (including several species of Eugenia), some Theaceae 

(including Haemocharis buxifolia and Schima wallichii) and a number of Sapotaceae 

constitute the main upper canopy species. In places the endemic Trevesia sumatrana 

(Araliaceae) grows gregariously by virtue of its root and stem-suckers. Other endemic 


trees include Horsfieldia atjehensis (Myristicaceae) and Mastrix octandra (Cornaceae). 

Common sub-canopy trees are Actinodaphne glomerulata, Chionanthus oxycarpus, 

Cinnamomum subavenium, Cryptocarya densiflora, Distylium stellare, Drypetes 

subsymetrica, Elaeocarpus mastersii, Eugenia longiflora, Ficus lanatus, Garcinia 

gaudichaudii, Lindera subumbelliflora, Memecylon oleifolium, Notaphoebe umbelliflora and 

Urophyllum arborescens. There are also many endemic small trees such as Brassaiopsis 

sumatrana (Araliaceae), Gomphandra dolichocarpa (Icacinaceae), Illicium sumatranum 

(Illiciaceae), Xanthophyllum ancolanum (Polygalaceae), and several endemic tree ferns 

like Cyathea senax and C. verrucosa (Cyatheaceae). Climbers are still relatively common 

and include, for example, the endemic Passiflora sumatrana (Passifloraceae). There are 

also many epiphytic species such as the endemic fern Pyrrosia asterosora 

(Polypodiaceae). The undergrowth is typically very rich in Myrsinaceae (such as Ardisia 

korthalsiana) and Rubiaceae (such as Hypobathrium microcarpum) but here also can be 

found several endemics like Lithocarpus orbicularis (Fagaceae), Polygala sumatrana 

(Polygalaceae), Rhododendron frey-wysslingii (Ericaceae) and Rubus banghamii 

(Rosaceae). The endemic titan arum, Amorphophallus titanium (Araceae) also occurs at 

these altitudes, and these forests form the main habitat of the magnifcent, endemic 

parasites Rafflesia micropylora and R. gadutensis (Rafflesiaceae) where they parasitize 

vines of the genus Tetrastigma. The herb layer mainly includes members of the 

Gesneriaceae (such as Cyrtandra anisophylla), Liliaceae (such as Dianella ensifolia) and 

Rubiaceae (such as Ophiorrhyza sansuinea). Other herbaceous ground layer species 

include several grasses like Lophatherum gracile and Joinvillea borneensis, ferns such as 

Diplazium cordifolium, and the endemic Trigonotis hirsuta (Boraginaceae), which seems to 

be mainly confined to elephant trails. 

Sumatran Upper Montane ‘Mossy’ Forest 

These forests range roughly between altitudes of 1900 to 2500 m in a zone where the 

cloud layer is relatively constant allowing moss and liverworts to flourish. On mountains 

such as Sinabung and the Talamau this generally coincides with a belt of the endemic 

Pandanus sumatranus (Pandanaceae), but the principal tree families are Fagaceae, 

Mystaceae and Theaceae. Other abundant canopy trees are Acronodia punctata, 

Lithocarpus suffruticosus, Symingtonia populnea and Vernonia arborea, which can reach 

heights of 25 m. Other noteworthy trees of the canopy are the three endemic species 

Glochidion lutescens (Phyllanthaceae), Rhododendron atjehense (Ericaceae) and 

Quercus steenisii (Fagaceae). Characteristic trees of the underlying layers are Michelia 

salicifolia, Saurauia micrantha, Weinmannia blumei and the endemic Symplocos robinsonii 

(Symplocaceae). Most trees are covered in a thick layer of epiphytic mosses and branches 

are usually festooned with Usnea lichens. Another characteristic feature of these forests is 

the abundance of aerial, epiphytic shrubs of the family Ericaceae such as the endemic 

Diplycosia cinnabarina, Rhododendron pibigermen and Vaccinium bartlettii, while other 

epiphytes include various endemic ferns of the genus Selliguea (Polypodiaceae) such as 

S. bakeri, S. brooksii and S. pseudoacrostichum. The shrub layer is often dominated by 

Ardisia javanica, while other less common species include Casearia tuberculata, Ilex 

triflora, Macropanax dispermus, Meliosma lanceolata, Myrica javonica, Neolitsea javonica, 

Saurauia micrantha, Schima wallichii, Viburnum lutescens, various endemic ericoids like 

Diplycosia tetramera and Rhododendron ridleyi (Ericaceae), and the endemic tree ferns 

Cyathea punctulata and C. trachypoda (Cyatheaceae), although neither of these is more 

than about 50 cm tall. On the ground common species are Calanthe flava, sedges like 

Carex cruciata and C. myosorus and ferns such as Asplenium caudatum, Athyrium 

gedeanum, Belvisia mucronata and Dryopteris poleacea. 


Sumatran Subalpine Forest 

Above the upper montane forest on Mt Kerinii from about 2400 to 2700 m is a peculiar 

zone dominated by ferns of the family Gleicheniaceae such as Dicranopteris pubigera and 

Gleichenia volubilis. It has never been fully explained in ecological terms since above this 

zone is another forest zone. These sub alpine forests, however, are very twisted and 

stunted and rarely achieve more than about 15 m in height. The dominant canopy trees 

are Ilex pleiobrachiata and Symplocos cochinchinensis var. sessilifolia, while a sub-canopy 

at about 10 m largely consists of Ardisia laevigata, Meliosma lanceolata and the endemic 

tree fern Cyathea trachypoda (Cyatheaceae). Below this are various shrubs including the 

endemic Gaultheria abbreviata and Rhododendron aequabile (Ericaceae). The forest floor 

is typically covered with the fern Plagogyria pycnophylla and the brambles Rubus 

elongatus and R. alpestris. Among the endemic herbaceous species at this altitude is 

Heracleaum sumatranum (Apiaceae). 

Sumatran Rhododendron-Vaccinium Alpine Scrub 

Above an altitude of about 3000 m most trees give way to a dense ericaceous scrub 

characterized by Rhododendron retusum and the endemic Vaccinium miquelii (Ericaceae). 

There are also many other endemic ericoids including Diplycosia atjehensis, D. glauciflora, 

D. sumatrensis, Gaultheria acroleia, G. atjehensis, G. kemiriense, Rhododendron 

adinophyllum, R. aequabile and R. sumatranum, while other endemic shrubs or small trees 

include Lithocarpus atjehensis (Fagaceae) and Symplocos sumatrana (Symplocaceae). 

One of the last trees to peter out is Myrica javanica but at these altidudes it grows no more 

than about 8 m high. The ground layer consists of tussocky species like Carex hypsophyla 

and Gahnia javanica and occasional herbs such as Anaphalis javanica and the two 

endemic species Pyrola sumatranum (Pyrolaceae) and Senecio sumatrana (Asteraceae). 

Ferns, such as Dicranopteris pubigera, Gleichenia volubilis and Hypolepis punctata, are 

also present. 

Further information required. 

Copyright © 2010 Peter Martin Rhind 

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Plant Formations in the Sumatran BioProvince - Terrestrial Biozones

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