Lindl.
Description
Calanthe sylvatica is a terrestrial orchid with one of the widest distributions in the genus, spanning from tropical and subtropical Africa (East Africa, Madagascar, Réunion, Comoros) to South and Southeast Asia (India, Bhutan, Nepal, Myanmar, China, Thailand, Vietnam). This pantropical range is reflected in GBIF's over 2,700 documented occurrences. In the Himalayas, it grows in the understory of humid broadleaved forests at 500–2,800 m elevation.
The plant is an evergreen species with inconspicuous pseudobulbs concealed by leaf sheaths. Leaves are 3–5, elliptic-lanceolate, 20–40 cm long, plicate, dark green. The inflorescence is an erect raceme 30–60 cm tall, bearing 10–30 flowers. Flowers are 2.5–3.5 cm across, typically deep violet to lilac-purple, though colour varies across the vast range from white to pink to deep purple. The lip is trilobed with a violet mid-lobe and a yellow callus with raised lamellae. The spur is slender, 1.5–2.5 cm long. In the Himalayas, flowering occurs from August to October.
The remarkable biogeographical range of Calanthe sylvatica — bridging Africa and Asia — has made it a subject of interest in orchid phylogeography. The Himalayan populations belong to the Asian lineage, and some taxonomists treat them as a distinct variety or subspecies. The species is adaptable and locally common in suitable habitats.
Author: Lindl. · Sources: POWO (Kew), Flora of Bhutan Vol. 3, GBIF, Cribb & Hermans: Field Guide to the Orchids of Madagascar (2009)