Geography and distribution
Bulbophyllum macranthum is native to Assam (India), Burma (Myanmar), Thailand, Cambodia, Vietnam, Nicobar Islands, Malaysia, Singapore, Sumatra, Java, Borneo, Philippines, Sulawesi, Moluccas, New Guinea and Solomon Islands. It is common in parts of this range, for example on the Nicobar Islands, but rare in others.
In some areas it can be confused with similar-looking species (B. praetervisum in Borneo, which differs in having a pair of downward-pointing teeth on the column, and B. grandifolium in New Guinea, which differs in having a triangular, rather than quadrangular, basal part of the lip).
Bulbophyllum macranthum grows in a very wide range of habitats, and has been collected in primary and secondary, evergreen, semi-deciduous and deciduous, broadleaf and coniferous, lowland to montane forests.
A robust, creeping, epiphytic (growing on other plants) orchid, with a rhizome 4–5 mm thick, which is covered with sheaths that break down leaving persistent fibres about 2 cm long. The pseudobulbs are about 3 cm tall and each bears a single 10–25 cm long, thick leathery leaf. The flowers are solitary, sometimes over 4 cm in diameter, and have fleshy, shiny sepals and petals. The dorsal sepals and petals are whitish with dense purple spotting and the lateral sepals are ochre-yellow, spotted with purple.
The British botanist Henry N. Ridley (1855-1956) described the flowers as smelling of cloves, while some have said they smell faintly of camphor.
Illustration of Bulbophyllum macranthum by Matilda Smith and John Nugent Fitch from Curtis's Botanical Magazine (1891).
Bulbophyllum macranthum is pollinated by fruit flies (Bactrocera species).
Threats and conservation
Many epiphytes have undergone a dramatic population decline, mainly because of habitat loss and timber extraction activities, which have driven many species close to extinction. Forests in parts of the region where Bulbophyllum macranthum occurs have been heavily logged, degraded and fragmented.
Bulbophyllum macranthum is a very attractive orchid, popular with hobbyists, and hence populations may suffer as a result of collection of individuals from the wild for the horticultural trade. The continued collection of Bulbophyllum macranthum in logged and secondary forests suggests that it is able to regenerate and persist in disturbed and secondary vegetation.
The species is currently listed on Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), meaning that international trade in it is controlled through permits.
Bulbophyllum macranthum is being monitored as part of the 'Sampled Red List Index' project, which aims to produce conservation assessments for a representative sample of the world’s plant species. This information will then be used to monitor trends in extinction risk and help focus conservation efforts where they are needed most.
Bulbophyllum macranthum is cultivated as an ornamental by orchid enthusiasts.
This species at Kew
Bulbophyllum macranthum is grown in the behind-the-scenes Tropical Nursery at Kew and can sometimes be seen on display in the Princess of Wales Conservatory.
Dried and alcohol-preserved specimens of Bulbophyllum macranthum are held in Kew’s Herbarium, where they are available to researchers from around the world by appointment. The details of some of these can be seen online in the Herbarium Catalogue.