Dipterocarpaceae

Dipterocarpaceae

Dipterocarpaceae is a family of 17 genera and approximately 500 species of mainly tropical lowland rainforest trees. The family name, from the type genus Dipterocarpus, is derived from Greek (di = two, pteron = wing and karpos = fruit) and refers to the two-winged fruit. The largest genera are Shorea (196 species), Hopea (104 species), Dipterocarpus (70 species), and Vatica (65 species). Many are large forest emergent species, typically reaching heights of 40-70 m tall, some even over 80 m (in the genera Dryobalanops, Hopea and Shorea), with the tallest known living specimen (Shorea faguetiana) 88.3 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 and Malaysia, with the greatest diversity and abundance in eastern Malaysia. Some species are now endangered as a result of overcutting, extensive illegal logging and habitat conversion. They provide valuable woods, aromatic essential oils, balsam, resins and are a source for plywood.

Classification

The dipterocarp family is generally divided into three subfamilies:  

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  • 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, but mostly in east Malaysia, where they form the dominant species in the lowland forests. North Borneo (Brunei, Sabah and Sarawak) is the richest area in the world for dipterocarp species. The Dipterocarpoideae can be divided into two groups:
    • Valvate-Dipterocarpi group (Anisoptera, Cotylelobium, Dipterocarpus, Stemonoporus, Upuna, Vateria, Vateriopsis, Vatica). The genera of this group have valvate sepals in fruit, solitary vessels, scattered resin canals, and basic chromosome number x = 11.
    • Imbricate-Shoreae group (Balanocarpus, Hopea, Parashorea, Shorea). 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 suggest that the genus Hopea forms a clade with Shorea sections Anthoshorea and Doona, and should be merged into Shorea.
  • Monotoideae: 3 genera, 30 species. Marquesia is native to Africa. Monotes has 26 species, distributed across Africa and Madagascar. Pseudomonotes is native to the Colombian Amazon.
  • Pakaraimoideae: contains a single species, Pakaraimaea roraimae, found in the Guaianan highlands of South America.

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 mass millions 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.

References

External links

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