by : Nalinda Wickramaarachchi (President of Thaprobane Orchid Society)
Introduction
Dendrobium maccarthiae or වෙසක් මල් (Wesakmal) is a rare orchid species with beautiful flowers that lives up to its nickname, Vesak orchid, from the most important Buddhist holiday.
Vesak commemorates the birth, enlightenment and death of Gautama Buddha, the founder of Buddhism. Vesak is celebrated on the full moon day of the month of Vesākha, which typically falls in May, corresponding to the flowering of Dendrobium maccarthiae. This orchid is endemic to Sri Lanka and classified as critically endangered on the 2012 IUCN Red List of Threatened Species. Dendrobium maccarthiae represents an important part of Sri Lankan culture and heritage. Furthermore, it is an important ecological indicator as its presence means a healthy forest ecosystem.
The Vesak Orchid has attracted the attention of collectors and traders since the colonial era thanks to its beauty, uniqueness and endemism. Unfortunately, the indiscriminate collection of wild orchids for ornamental purposes caused a decline in their populations in 1900. In 1937 this species was declared protected by the Flora and Fauna Ordinance.
Distribution
The Vesak Orchid grows in Sri Lanka’s humid forests at elevations of 100-1000 meters above sea level. It prefers shady areas with moist conditions. Sri Lanka is an island nation located in the Indian Ocean, southwest of the Bay of Bengal and southeast of the Arabian Sea, separated from the Indian subcontinent by the Gulf of Mannar and the Palk Strait. Dendrobium maccarthiae is the provincial flower of the Sabaragamuwa Province in Sri Lanka The core area of the distribution of Dendrobium maccarthiae is the northern and western parts of the Ratnapura and Kalutara Districts. The flower also grows in the western parts of Kegalle, the southern part of Colombo, and the northern part of the Galle District.
Physical characteristics
Dendrobium maccarthiae, is an epiphyte with slender, terete, pendulous, pseudobulbs stems 16-60 cm long and tufted fibrous roots; internodes 1-4 cm long and leaves borne clustered at the apices of the stems, one to each node. Leaves, 4-8 x 0.9-1.3 cm lanceolate, acuminate, membranous, veins parallel, midrib prominent beneath, bases sheathing the internodes; leaf sheaths 2 cm long, green when young but mottled brown when old, appressed to the internodes. Flowers, light violet-pink, lip paler but with a purple blotch in the center and on the disc, 5.5-6 cm long, 7.5 cm across, in lax, pendulous, 2-4-flowered, drooping racemes which measure 9-11 cm in length; peduncle 2-3 cm long with short, imbricate, basal, sterile bracteolar sheaths; pedicel arched at the point where it meets the ovary; floral bracts 0.6-0.3 x 0.3 cm, lanceolate, subulate, pale brown, papery, 3-veined; dorsal sepal 3.5-4 x 1 cm, lanceolate, acuminate, acute, 7-veined; lateral sepals 4-4.5 x 1.3 cm, subfalcately lanceolate, acuminate, acute, bases adnate to the foot of the column; petals 4-4.3 x 1.9 cm, oblong-lanceolate or ovate-oblong, acuminate, acute, margins slightly rolled back, 5-veined; lip 6 x 3 cm, rhomboid or subspathulate; lateral lobes rounded convolute; midlobe broadly ovate, mucronate; column 0.4 cm high, 3-toothed at the top, the center tooth short, straight and pointed, the lateral teeth recurving, the two projections of the operculum fitting into the spaces between the teeth; column continued into a foot, 1.6 cm long and 0.6 cm broad; mentum short, straight and conical. Anther terminal, versatile, 2-loculed, 2 x 2.4 mm, helmet-shaped with 2 projections behind to which the pollinia are attached when they are dislodged; pollinia 4, lodged in an operculum which articulates with the column by a narrow neck, oblong, collateral in pairs, sightly adhering to a viscus: each pollinium 2.3 x 0.44 mm. Ovary with pedicel 2.4-3.1 cm long. Fruit a loculicidal, fusiform capsule 3.2 x 1.17 cm diameter. Dendrobium maccarthiae blooms in May-July, during the Vesak season.
Ecology
Dendrobium maccarthiae grows in tropical lowland evergreen forests of Sri Lanka. Rainfall is over 3810 mm per year with a relative humidity of 75-85 per cent. Annual average temperatures are usually above 26°C. The amount of sunlight that these plants get is about 28-61 per cent of normal sunlight. Some of the host plants on which it grows include Hevea brasiliensis, Wendlandia bicuspidata, Wormia triquetra, Elaeocarpus serratus, and Dipterocarpus zeylanicus.
Etymology
Dendrobium maccarthiae is named after Mrs. MacCarthy wife of Charles Justin MacCarthy, who was the Colonial Secretary of Ceylon at that time (1855).
Cultivation Note
The Vesak Orchid is also a popular plant among orchid enthusiasts, however it is a rather difficult plant to grow outside of its own habitat. One of the biggest challenges of growing the Vesak Orchid is providing it with the right temperature and humidity. The Vesak Orchid is a tropical plant that loves tropical lowland warm temperatures and high humidity to grow well. This can be difficult especially during the winter months in temperate climate countries. The Vesak Orchid also prefers bright, indirect light. Too much sunlight can scorch the leaves, too little can prevent the plant from flowering. Finally, the Vesak Orchid is a slow growing plant. It can take 3 – 4 years for a Vesak Orchid seedling to reach maturity and bloom.
Conservation
Vesak Orchid is a protected plant in Sri Lanka under the Flora and Fauna Protection Decree. This means that it is illegal to remove it from its natural habitat or collect it where it grows wild. The Flora and Fauna Protection Decree was passed to protect the unique flora and fauna of Sri Lanka. It covers a list of plants and animals protected by law which also includes the Vesak Orchid. In fact, Dendrobium maccarthiae is a particularly important plant as it is endemic to Sri Lanka, which means it is unobtainable in the rest of the world, and it represents an important part of the Sri Lanka’s culture and tradition.
Threats and Measures Taken
The main threats to the conservation of Dendrobium maccarthiae include:
- Loss of habitat. The marshy lowlands of Sri Lanka, where Dendrobium maccarthiae grows, are undergoing intense deforestation for agricultural purposes and for anthropogenic development.
- Excessive collection. Religious ceremonies such as the Vesak festival uses Dendrobium maccarthiae as offering to temples. It is important to note that Dendrobium maccarthiae is an endangered species and its flowering period is relatively short. Therefore, flower harvesting has a negative impact on the orchid population.
- Climate change. Climate change is expected to lead to increasingly extreme weather events, such as drought and floods, which threatens populations of Dendrobium maccarthiae.
Various measures have already been taken to promote the conservation of this endangered species. Some things we can all do to help conserve Dendrobium maccarthiae, such as:
- forming protected areas in the locations where the orchid grows spontaneously. This protect its habitat from anthropogenic development and other threats;
- raise people’s awareness of the problems affecting Dendrobium maccarthiae can help reduce indiscriminate collection and support conservation activities;
- propagate and plant Dendrobium maccarthiae to increase their population and compensate for the impact generated by habitat loss and indiscriminate harvesting.
Illegal trade
As a protected orchid, trade in Dendrobium maccarthiae in Sri Lanka is illegal. Unfortunately, a large number of exchanges take place mainly on social media and represent a serious problem. Collectors often do not just take flowers but even remove entire wild plants, without caring at all about the sustainability of this behavior for the species. Moreover, indiscriminate collection can in fact also lead to the destruction of its habitat. Here’s a list of things you can do to help protect Dendrobium maccarthiae:
- avoid purchasing Dendrobium maccarthiae plants or flowers on social platforms or other unreliable sites;
- support organizations dedicated to conservation activities that work to protect Dendrobium maccarthine and its habitat;
- inform people about the illegal trade of Dendrobium maccarthiae and the impact this has on its wild population.
By working together we can protect this beautiful and unique orchid from illegal trade.
Bibliography
“A Revised Handbook to the Flora of Ceylon”, vol. II, editor M. D. Dassanayake. published by A. A. Balkema, Rotterdam, 1981.