The Orchideous House is a small ruined glasshouse situated centrally within the walled kitchen garden of Penllergaer. The building is without its superstructure but its walls appear to stand more or less to their full height. Immediately to its east are the remains of the coal pit and structures associated with the fireplace and boiler that enabled hot water to be cascaded into the glasshouse. The structure was re-designed by John Dillwyn Llewelyn in 1843 from a simple glasshouse for orchids to a glasshouse with a hot water cascade to mimic the conditions for non-terrestrial orchids.
Source: Cadw scheduling description of December 2007. RCAHMW 19.12.2007