Durian Botany
Botanically speaking, the durian is a member of the plant family Malvaceae. The durian is the fruit of several tree species belonging to the genus Durio
(some taxonomists place Durio in a distinct family by itself,
Durionaceae, but that is a different story and we won't deal with it
here).
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Malvales
Family: Malvaceae
Subfamily: Helicteroideae
Tribe: Durioneae
Genus: Durio
Durio zibethinus L. is the only species of durian commercially cultivated on a large scale and available outside of its native region. Since this species is open-pollinated, it shows many differences in fruit colour and odour, size of flesh and seed, and tree characteristics and growth.
The Common Durian - Durio zibethinus L.
Durian Tree
The durian tree looks regal and majestic befitting its royal title as "King of Fruits".
In its natural environment, the common durian tree has a tall, broadly conical frame tapering to an apex. It is an evergreen tropical tree with a straight trunk and buttressed base. A matured tree trunk can be 50-120 cm in diameter.
The durian wood is classified as softwood, coarse, lightweight and is not durable and seldom used for building construction but is used for making light furniture and clogs. The dark brown bark is rough and peels off irregularly.
The branches grow out from the trunk in all directions. The trees’ thin branchlets are coated with coppery or gray scales when young. Some matured trees usually have upper branches which are almost horizontal.
In its natural state in a rainforest, a durian trees usually grow to a height of 30-40 m with some exceptional trees reaching a majestic height of 60 m. It has a very long life of 80-150 years or more. However, durian trees seldom exceed 12m when grown as grafted clones in durian orchards.
A durian tree grown from seed has one tap root going directly down from the trunk. Secondary roots grow out from the tap root. However, if the durian tree is grown by vegetative propagation, the tree will not have a primary tap root. Instead it will have adventitious or secondary roots growing directly from the base of the trunk.
Durian is unique as it does not have root hairs. Instead, the roots that absorb water and nutrients are called fungus roots which grow out from the secondary or tertiary roots. They are shallow-rooted and grow only within about 50 cm of the soil surface.
Durian Leaf
The leaves are simple and alternate, lanceolate in shape, 10–20 cm long and 3-7.5 cm wide with a glossy olive or dull green smooth upper surface and velvety, shiny bronze lower surface due to the dense covering of overlapping hairs or scales. This unique combination of colours is very attractive as the leaves appear to change colour when the wind blows through the tree. Leaf stalks are round, about 2.5 cm long. Leaf apexes are acuminate. When new leaves first appear, they are folded at the mid-rib. As the leaves mature they stretch out.
Shoot growth appears to be continuous but there are usually 2-5 vegetative flushes during a season.
The common durian flowers are ramiflorous, i.e. the flowers are borne along big branches that are capable of bearing the weight of mature fruits.
Flowering occurs in clusters of 2–45 flowers over a period of about 3–4 weeks during the dry season.
The flower stalks or pedicels, 5–7 cm long, support globose flower buds 2
cm in diameter, opening to reveal 5–6 cm long, greenish-white flowers.
The tubular calyx has three to five triangular teeth surrounding five petals.
Durian has complete or perfect flowers. Stamens are arranged in five bundles around a pubescent style and protruding capitellate stigma.
There are differences in colour and shape of durian stigmas. Some clones (e.g. D8, D24, D104) have 5-lobed stigmas, whereas some have no lobes. Some stigmas are top-shaped (e.g. D2, D88, D96) while others are broad and flat (D16, D66). Stigma shape is highly consistent within a clone. Clones D8, D66 and D104 have bright orange stigmas while some have yellow stigmas.
A period of 3 to 4 weeks dry weather is needed to stimulate flowering. It takes about one month for a durian flower to develop from first appearance as a tiny bud to an open blossom.
As a flower matures, the outer fleshy part (the epicalyx) splits to reveal 5 united sepals and 5 petals. It has been observed that the colour of the sepals and petals match the color of the edible flesh or pulp that will develop inside the fruit. Durian trees with yellowish flowers produce yellow-fleshed durians (the most common), while those with white or reddish petals will have white or reddish fleshed fruit.
Durian flowers are hermaphrodites i.e. each flower has a stamen
and pistil. However, self-pollination rarely happens, for when the
flowers are open, normally from 3 p.m. to about midnight, the pistil and
the stamen do not appear at the same time. The female stigma from the
pistil usually comes out first, long before the anthers of the stamen
appear and shed their pollen. And by the time the pollen is active, the
stigma is no longer receptive. By midnight most pollen has been shed and
all flower parts except the pistil fall to the ground.
Even if the female and male flower parts of durian flowers are active at the same time, most durian trees have a high degree of self-incompatibility. In other words, the flowers must be cross-pollinated from other trees in order to set fruit.
However, some cultivars or clones such as the Thai Chanee and Kanyao are self-compatible but natural fruit set is very low. It has been reported that in natural and self-pollinated Chanee, the fruit seed is 0 to 6%; and in Kanyao 21%.
Durian flowers are large and feathery with copious nectar, and give off a heavy, sour and buttery odour. These features are typical of flowers pollinated by certain species of bats that eat nectar and pollen.
According to research conducted in Malaysia in the 1970s, durians were pollinated almost exclusively by cave fruit bats, or also known as Pterodids. Eonycteris spelaea and M. minimus are the two nectarivorous bats responsible for pollinating durian flowers.
Durian fruit development takes about 95–130 days after pollination depending on the varieties or cultivars. Fruit ripening usually heralds the start of the rainy season.
The durian fruit is famous for its strong odour and unique taste. The fruit is large (between 2 and 5 kg), pendulous, round to oblong in shape, covered with strong sharp spines or thorns. The husk or pericarp is yellow–green to green or brown in colour and does not change significantly with ripening.
The durian fruit is actually a capsule and the edible sections are technically called arils. The aril is a fleshy outgrowth of the seed’s own outer covering which starts to form as a white sheet 4 weeks after successful flower pollination. The aril or pulp varies extensively between cultivars in color, aroma, flavor, texture, thickness, and color. As the fruit matures, the flesh softens and the whitish color changes to cream, yellow or deep orange, and the characteristic smell of the durian becomes more defined.
The characteristic strong odour and flavour is due to the production of volatile compounds. More than 40 volatile flavouring compunds have been identified from durian samples from various cultivars or varieties. Some research indicate that the odour originates from a complex mixture of thiols, esters, thioethers and sulfides. Read more HERE
The fruit usually comprises five sections or compartments called locules. Each locule holds one to seven large brown seeds covered in the edible flesh (aril).
Some locules have incomplete and infertile seeds due to lack of pollination. Some cultivars or clones exhibit this undesirable characteristic more regularly than with others.
The durian flesh or pulp (arils) typically comprises 15–35% of the fruit weight, and are composed of about 2.5% protein, 2.5% fat, 28% carbohydrate and 67% water, with smaller amounts of fiber, minerals and vitamins.
Below are some interesting nutrition facts about the durian provided by the United States Department of Agriculture.
Ripe durian pulp or arils packaged in foam trays and over-wrapped with plastic or PVC film are a familiar sight in supermarkets and getting popular with customers.
Durian fruit is preserved by freezing, or in the form of a paste or cake that is used to flavour ice-cream, bread or pastries, or the fruit can be fermented, salted or boiled in sugar syrup.
Durian seeds are round or heart-shaped with yellow-brown or red-brown colour depending on the cultivars or clones.
Durian seeds are poisonous when eaten raw because of cyclopropene fatty
acids but are very palatable when boiled, fried or roasted and have a
texture that is similar to taro or yam, but stickier.
Fresh seed germinates within 3–8 days to produce a fast-growing seedling that shows strong apical dominance.
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Malvales
Family: Malvaceae
Subfamily: Helicteroideae
Tribe: Durioneae
Genus: Durio
Durio zibethinus L. is the only species of durian commercially cultivated on a large scale and available outside of its native region. Since this species is open-pollinated, it shows many differences in fruit colour and odour, size of flesh and seed, and tree characteristics and growth.
The Common Durian - Durio zibethinus L.
Tall conical tree frame of the durian
Durian Tree
The durian tree looks regal and majestic befitting its royal title as "King of Fruits".
In its natural environment, the common durian tree has a tall, broadly conical frame tapering to an apex. It is an evergreen tropical tree with a straight trunk and buttressed base. A matured tree trunk can be 50-120 cm in diameter.
The durian wood is classified as softwood, coarse, lightweight and is not durable and seldom used for building construction but is used for making light furniture and clogs. The dark brown bark is rough and peels off irregularly.
Straight trunk, buttressed base
The branches grow out from the trunk in all directions. The trees’ thin branchlets are coated with coppery or gray scales when young. Some matured trees usually have upper branches which are almost horizontal.
In its natural state in a rainforest, a durian trees usually grow to a height of 30-40 m with some exceptional trees reaching a majestic height of 60 m. It has a very long life of 80-150 years or more. However, durian trees seldom exceed 12m when grown as grafted clones in durian orchards.
Straight trunk and horizontal upper branches
 |
| A shorter and more compact clonal tree - D197 - Musang King |
Durian Roots
A durian tree grown from seed has one tap root going directly down from the trunk. Secondary roots grow out from the tap root. However, if the durian tree is grown by vegetative propagation, the tree will not have a primary tap root. Instead it will have adventitious or secondary roots growing directly from the base of the trunk.
Durian is unique as it does not have root hairs. Instead, the roots that absorb water and nutrients are called fungus roots which grow out from the secondary or tertiary roots. They are shallow-rooted and grow only within about 50 cm of the soil surface.
Durian Leaf
Durian leaves are very distinctive
The leaves are simple and alternate, lanceolate in shape, 10–20 cm long and 3-7.5 cm wide with a glossy olive or dull green smooth upper surface and velvety, shiny bronze lower surface due to the dense covering of overlapping hairs or scales. This unique combination of colours is very attractive as the leaves appear to change colour when the wind blows through the tree. Leaf stalks are round, about 2.5 cm long. Leaf apexes are acuminate. When new leaves first appear, they are folded at the mid-rib. As the leaves mature they stretch out.
Flushing - new leaves appear 2 - 5 times a year
Flower buds and flowers
Durian Flowers
The common durian flowers are ramiflorous, i.e. the flowers are borne along big branches that are capable of bearing the weight of mature fruits.
Flowering occurs in clusters of 2–45 flowers over a period of about 3–4 weeks during the dry season.
 |
| Clusters of durian flowers - D24 |
The tubular calyx has three to five triangular teeth surrounding five petals.
Durian has complete or perfect flowers. Stamens are arranged in five bundles around a pubescent style and protruding capitellate stigma.
There are differences in colour and shape of durian stigmas. Some clones (e.g. D8, D24, D104) have 5-lobed stigmas, whereas some have no lobes. Some stigmas are top-shaped (e.g. D2, D88, D96) while others are broad and flat (D16, D66). Stigma shape is highly consistent within a clone. Clones D8, D66 and D104 have bright orange stigmas while some have yellow stigmas.
 |
| An unopened bud and several buds about to open. One bud has already shed its petals and stamens. |
A period of 3 to 4 weeks dry weather is needed to stimulate flowering. It takes about one month for a durian flower to develop from first appearance as a tiny bud to an open blossom.
As a flower matures, the outer fleshy part (the epicalyx) splits to reveal 5 united sepals and 5 petals. It has been observed that the colour of the sepals and petals match the color of the edible flesh or pulp that will develop inside the fruit. Durian trees with yellowish flowers produce yellow-fleshed durians (the most common), while those with white or reddish petals will have white or reddish fleshed fruit.
 |
| A durian flower - D197 or Musang King |
 |
| Durian sepal, petals and stamens lying on the ground |
Even if the female and male flower parts of durian flowers are active at the same time, most durian trees have a high degree of self-incompatibility. In other words, the flowers must be cross-pollinated from other trees in order to set fruit.
However, some cultivars or clones such as the Thai Chanee and Kanyao are self-compatible but natural fruit set is very low. It has been reported that in natural and self-pollinated Chanee, the fruit seed is 0 to 6%; and in Kanyao 21%.
Durian flowers are large and feathery with copious nectar, and give off a heavy, sour and buttery odour. These features are typical of flowers pollinated by certain species of bats that eat nectar and pollen.
According to research conducted in Malaysia in the 1970s, durians were pollinated almost exclusively by cave fruit bats, or also known as Pterodids. Eonycteris spelaea and M. minimus are the two nectarivorous bats responsible for pollinating durian flowers.
A fruit bat feeding on durian flower nectar
Head of a cave fruit bat - E. spelaea
Durian fruit development takes about 95–130 days after pollination depending on the varieties or cultivars. Fruit ripening usually heralds the start of the rainy season.
 |
| Young durian fruitlets of D24. |
 |
| A bunch of D24 durians |
 |
| Durian fruits of D197 or Musang King at various stages of ripening on a branch |
Durian Fruit
The durian fruit is famous for its strong odour and unique taste. The fruit is large (between 2 and 5 kg), pendulous, round to oblong in shape, covered with strong sharp spines or thorns. The husk or pericarp is yellow–green to green or brown in colour and does not change significantly with ripening.
Different parts of an opened durian
The durian fruit is actually a capsule and the edible sections are technically called arils. The aril is a fleshy outgrowth of the seed’s own outer covering which starts to form as a white sheet 4 weeks after successful flower pollination. The aril or pulp varies extensively between cultivars in color, aroma, flavor, texture, thickness, and color. As the fruit matures, the flesh softens and the whitish color changes to cream, yellow or deep orange, and the characteristic smell of the durian becomes more defined.
The characteristic strong odour and flavour is due to the production of volatile compounds. More than 40 volatile flavouring compunds have been identified from durian samples from various cultivars or varieties. Some research indicate that the odour originates from a complex mixture of thiols, esters, thioethers and sulfides. Read more HERE
The fruit usually comprises five sections or compartments called locules. Each locule holds one to seven large brown seeds covered in the edible flesh (aril).
Five locules of an opened durian fruit
Some locules have incomplete and infertile seeds due to lack of pollination. Some cultivars or clones exhibit this undesirable characteristic more regularly than with others.
 |
| Clone D2 (Dato Nina) exhibiting incomplete or shriveled seeds (right section) |
The durian flesh or pulp (arils) typically comprises 15–35% of the fruit weight, and are composed of about 2.5% protein, 2.5% fat, 28% carbohydrate and 67% water, with smaller amounts of fiber, minerals and vitamins.
Below are some interesting nutrition facts about the durian provided by the United States Department of Agriculture.
 |
| Source: The USDA National Nutrient Database for Standard Reference is one of the most comprehensive sources for evaluating the nutrient content of close to 8,000 food items. It is a major source of food composition used by both private and public sectors. |
Ripe durian pulp or arils packaged in foam trays and over-wrapped with plastic or PVC film are a familiar sight in supermarkets and getting popular with customers.
Fresh durian fruits and durian flesh in PVC-wrapped foam tray
Durian fruit is preserved by freezing, or in the form of a paste or cake that is used to flavour ice-cream, bread or pastries, or the fruit can be fermented, salted or boiled in sugar syrup.
Durian seeds
Durian Seeds
Durian seeds are round or heart-shaped with yellow-brown or red-brown colour depending on the cultivars or clones.
Boiled durian seeds on the left and fresh seeds on the right
Germinating seeds about 7 days old
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