The Dipterocarpaceae are a family of 16 genera and about 695 known species of mainly tropicallowlandrainforest trees. The family name, from the type genusDipterocarpus, is derived from Greek and refers to the two-winged fruit. The largest genera are Shorea, Hopea, Dipterocarpus, and Vatica. Many are large forest-emergent species, typically reaching heights of 40–70 m, some even over 80 m, with the tallest known living specimen 93.0 m tall. The species of this family are of major importance in the timber trade. Their distribution is pantropical, from northern South America to Africa, the Seychelles, India, Indochina, Indonesia, and Malaysia. The greatest diversity of Dipterocarpaceae occurs in Borneo. Some species are now endangered as a result of overcutting, extensive illegal logging, and habitat conversion. They provide valuable woods, aromatic essential oils, balsam, and resins, and are a source for plywood.
Classification
The dipterocarp family is generally divided into two subfamilies:
Dipterocarpoideae: the largest of the subfamilies, it contains 13 genera and about 475 species. Distribution includes the Seychelles, Sri Lanka, India, Southeast Asia to New Guinea, and a large distribution in Borneo, where they form the dominant species in the lowland forests. North Borneo is the richest area in the world for dipterocarp species. The Dipterocarpoideae can be divided morphologically into two groups, and the tribe names Shoreae and Dipterocarpeae are sometimes used, but genetic evidence so far does not support this division:
*Valvate - Dipterocarpeae group. The genera of this group have valvate sepals in fruit, solitary vessels, scattered resin canals, and basic chromosome number x = 11.
* Imbricate - Shoreae group. The genera of this group have imbricate sepals in fruit, grouped vessels, resin canals in tangential bands, and basic chromosome number x = 7. A recent molecular study suggests that the genus Hopea forms a clade with Shorea sections Anthoshorea and Doona, and should be merged into Shorea.
Monotoideae: three genera, 30 species. Marquesia is native to Africa. Monotes has 26 species, distributed across Africa and Madagascar. Pseudomonotes is native to the Colombian Amazon.
A recent genetic study found that the Asian dipterocarps share a common ancestor with the Sarcolaenaceae, a tree family endemic to Madagascar. This suggests that ancestor of the dipterocarps originated in the southern supercontinent of Gondwana, and that the common ancestor of the Asian dipterocarps and the Sarcolaenaceae was found in the India-Madagascar-Seychelles land massmillions of years ago, and were carried northward by India, which later collided with Asia and allowed the dipterocarps to spread across Southeast Asia and Malaysia. The first dipterocarp pollen has been found in Myanmar and it dates from the upper Oligocene. The sample appears to slowly increase in terms of diversity and abundance across the region into the mid-Miocene Chemical traces of dipterocarp resins have been found dating back to the Eocene of India. Subfamily Pakaraimoideae formerly placed here and native to the Guaianan highlands of South America, is now found to be more closely related the Cistaceae and is placed there in the APG IV
Fossilized arthropods
Some 52-million-year-old amber found in the Gujaratprovince, India, containing a large amount of fossilized arthropods, was identified as sap from the family Dipterocarpaceae.
Ecology
Dipterocarpaceae species can be either evergreen or deciduous. Species occurring in Thailand grows from sea level to about 1300 m elevation. Environments in which the species of the family occur in Thailand include lowland dipterocarp forest 0–350 m, riparian fringe, limestone hills, and coastal hills.
