Gastrochilus retrocallus (≡ Haraella retrocalla)
Habitat:
This micro‑miniature orchid is endemic to Taiwan, occurring in sunny-deciduous or mixed forests at elevations of 500–2200 m, especially around Taipei, Taitung, and Iriomote Island. It grows as an epiphyte on mossy tree trunks and thin branches in humid, shady forest understories and on ridges with frequent fog and moisture  .
Description:
A tiny monopodial epiphyte, G. retrocallus usually reaches just 1–2 cm tall. Leaves are distichous, fleshy, falcate to oblanceolate, and 3–7 cm long  . Inflorescences are axillary, pendulous spikes of up to 3 sequential, showy flowers (~2–2.5 cm across) in yellow to pale green, often with a contrasting red or mahogany-spotted lip and a distinct citrus-like scent that mimics female beetle pheromones for pollination  . The species epithet “retrocallus” refers to its reflexed callus on the labellum.
Cultivation:
Gastrochilus retrocallus prefers bright, filtered light with temperatures of 21–26 °C daytime and 13–17 °C at night, with humidity levels of 70–85% . Best grown mounted on bark or cork slab with a bit of sphagnum or as a fine-mix potted orchid. It should be watered often—daily when mounted, or every 2–3 days in pots, using low-mineral water and with excellent airflow. Fertilize lightly—weekly or biweekly—with a dilute balanced or bloom-promoting formulation, flushing media regularly to prevent salt buildup  .
Specifications:
Plant Size: established, flowering size, and growing on mounts. 
Plant Family: Orchidaceae
Plant Passport: Gastrochilus retrocallus B 140084 C 765 D GB