Durio graveolens

D. graveolens is a large,^[2] up to 50 m (160 ft) tall upper canopy tree.^[5][12] The trunk is 85–100 cm (33–39 in) in diameter and can have no branches until about 25 m (82 ft) high.^[5] The trunk is smooth or flaky, grey/mauve to ruddy brown with steep buttress roots.^[5] The buttresses reach 3 m (9.8 ft) and extend out 1.5 m (4 ft 11 in).^[12]

The oblong leaves are 10–26 cm (3.9–10.2 in) long without the petiole (leaf stalk), and 4–10 cm (1.6–3.9 in) wide.^[2][5] They are perfectly rounded on both ends, rigid, and slightly coriaceous (leather-like in feel or texture).^[5][2] On the top, they are glabrous (smooth and hairless) and crisp,^[5] almost vernicose (varnished).^[2] Underneath, the leaves are copper-brown and lepidote (scaly),^[5] with large scales of up to 2 mm (0.079 in) in diameter, which are not very noticeable, at least when dry.^[2] The leaf scales are peltate (shield-shaped), ciliate-radiated (fringed), and deeply-lobed in three to five parts.^[2] In addition to the scales, long strands of stellate hairs and other trichomes of varying size form a soft tomentose (fuzzy) surface.^[2] The leaf midrib is very prominent on the underside and forms a crease on top.^[2] The leaf stipules are caducous (drop early).^[5] Leaves have 10–12 lateral veins per side (with some smaller ones intermixed), which are tiny and superficial above and more distinct, but still barely visible.^[2] The petiole is very large, 15–18 mm (0.59–0.71 in) long, and tumescent (swollen) from the middle up.^[2]

Flowers grow on the branches^[2][14] on short cymes.^[5] The base is sac-like with three to five connate lobes.^[5][14] It has white,^[14] spatulate (spoon-shaped) petals that are 25–35 millimetres (0.98–1.38 in) long.^[5] Inside are five separate bundles of staminodes and stamens,^[5] fused for less than half of their length.^[14] The anther has small clusters of four or five elongated pollen locules that open with longitudinal slits.^[14] Ovaries are ovoid to globose (roughly spherical) and possess a yellow capitate (shaped like a pinhead) stigma and white to greenish style^[5] about 48 mm (1.9 in).^[15] The pollen is psilate (relatively smooth), spheroidal, and 54 μm (0.0021 in) in diameter.^[15] The surface of the pollen includes three colporate apertures, meaning the apertures have a combined colpus (or furrow) and pore.^[15] The pollen grains are monad and do not cluster.^[15]

The fruits are up to 10–15 cm (3.9–5.9 in) in diameter,^{[2][5][11][16][14]} and weigh about 757.5 grams (26.72 oz).^[17] The greenish- to orange-yellow outside is densely covered with long (1 cm (0.39 in)) and thin angular-subulate spines which are straight or slightly curved, and prickly^[2][5][11] yet slightly soft.^[14] The fruit easily breaks into five fibrous-coriaceous valves (sections)^[5][11][16] with 5–6 millimetres (0.20–0.24 in) thick walls.^[2] Typically the fruit opens on the tree,^[5][11] but some varieties do not until they are on the ground or harvested. There are 2 bulbous or chestnut-shaped seeds per section, each completely enveloped by fleshy aril.^[2][11][14] These glossy brown seeds are 2 cm × 4 cm (0.79 in × 1.57 in).^[5][11][16] The pungent aril is the part consumed as food,^[2] though some sources note the odor is sometimes very mild.^[11][14][12] It ranges in color from light yellow^[2] to orange to lipstick red.^{[5][4][11][14]}

• 
  Trunk
• 
  Foliage
• 
  Fruit

After its initial description in 1889 by Odoardo Beccari, in 1924, Dutch botanist Reinier Cornelis Bakhuizen Van Den Brink reduced it to a synonym of D. conicus. British botanist John Wyatt-Smith combined it all under D. dulcis in 1953. Indonesian botanists André Joseph Guillaume Henri Kostermans and Wertit Soegeng-Reksodihardjo separated D. graveolens back to its own species in 1958.^[18]

This species should not be confused with the popular durian clones from Malaysia known as 'Red Flesh' (D164) and 'Red Prawn' (D175), as both of those belong to D. zibethinus.^[19] A natural hybrid of D. graveolens and D. zibethinus is called durian siunggong or durian suluk.^[4][5][9] It has the texture and flavour of the popular D. zibethinus and the burnt caramel overtones of D. graveolens.^[5][4]

However, D. graveolens does have one registered variety, 'DQ2 nyekak (DK8)'.^[19] The color of the fruit's flesh denotes other varieties–an orange-fleshed, a red-fleshed one, and yellow-fleshed. These varieties may be different species, but currently there is no consensus.^[9][13] The yellow-fleshed kind is sometimes called durian simpor.^[9][5][4]

D. graveolens is in the core clade Palatadurio of the genus Durio.^[14] It is most closely related to Durio kutejensis.^[14]

Wild D. graveolens grows in Peninsular Malaysia^{[5][12][4][11]} (states of Johor, Kedah, Kelantan, Malacca, Penang, Perak, Selangor, and Terengganu), Indonesian Islands of Borneo^{[5][12][4][11]} and Sumatra,^{[12][11][4][5]} Palawan,^[4] and Southern Thailand.^[28] It is cultivated in Brunei,^[4] Sarawak, Sabah,^[5] and the Northern Territory of Australia.^[11] In Brunei, its popularity outshines D. zibethinus,^[21] which is not cultivated in the country.^[29]

It is occasionally grown outside the tropics. In Florida, it has been seen to survive two consecutive nights at 0 °C (32 °F), albeit shrouded in cloth.^[30]

D. graveolens is a tropical plant species that needs high heat and humidity.^[5] Typically, it is found on clay-rich soils in wet lowland dipterocarp forests, frequently along riverbanks and swamps.^[5] Because of its tolerance for wet habitats,^[12] it is possibly resistant to infection by the oomycete Phytophthora palmivora.^[11][21] It can also be found on hillsides and shale ridges up to 1,000 m (3,300 ft) in elevation.^[5]

It is pollinated by bats.^[15] As it is one of the only species to naturally hybridize with D. zibethinus,^[4][5][31] they are thought to share a pollinator, likely the cave nectar bat (Eonycteris spelaea).^[32][18] Pollen from both of these durian species has been found in cave nectar bat feces, and possibly in that of the long-tongued fruit bat (Macroglossus sobrinus).^[33]

After harvest, fruit can be set upon by fungi such as Lasiodiplodia theobromae, Glomerella cingulata, Geotrichum candidum, Calonectria kyotensis, and occasionally Gliocephalotrichum bulbilium.^[21] Secondary or opportunistic fungal infection can be from species such as Aspergillus niger and other Aspergillus spp., Candida spp., Gibberella intricans, and Penicillium spp.^[21]

The fruit is fed on by Bornean orangutans (Pongo pygmaeus),^[23] Prevost's squirrels (Callosciurus prevostii), crab-eating macaques (Macaca fascicularis), black hornbills (Anthracoceros malayanus), possibly viverrids^[16] and sun bears (Helarctos malayanus).^[34] Black hornbills are also effective seed dispersers for the tree,^[16] and this is referenced in a few of the regional names for the tree (see § Names).

It is a vulnerable species.^[1]

The fatty acids in the fruit are 30% saturated and 70% unsaturated.^[22] The saturated fats include myristic acid (14.49%), arachidic acid (7.08%), pentadecanoic acid (3.61%), heptadecanoic acid (2.2%), decanoic acid (1.62%), and lauric acid (1.31%).^[22] Unsaturated fats include oleic acid (22.18%), palmitoleic acid (13.55%), linolelaidic acid (12.39%), γ-linolenic acid (12.23%), linoleic acid (4.95%), elaidic acid (2.50%), and myristoleic acid (1.89%).^[22]

The fruit's pulp is typically eaten raw and has the fragrance of roasted almonds^[5][4][21] or burnt caramel.^[5][4] The taste is described as sweet and cheesy^[21] or similar to eating an avocado or pimento cheese.^[9] Sometimes, it is fermented into the condiment tempoyak.^[13] The red-fleshed type is used with freshwater fish to make a type of sayur (a traditional Indonesian vegetable stew).^[5]

The seeds can also be ground into flour (tepung biji durian dalit), which then can be used to make, for example, fish crackers.^[26]

The tree is also harvested for lumber in Sarawak.^[5] The Iban people there also bathe day-old infants (especially for preterm birth) in a tisane of mature bark, as they believe it strengthens the skin.^[5]

• List of Durio species
• Durian Burung, a town in Malaysia