Megistostegium perrieri grows as a shrub up to 1 metre (3 ft) tall.

The flowers are pendant with an epicalyx that matures to a deep maroon colour.

[3] Megistostegium perrieri is found only on the coastline of the Mahafaly Plateau of Toliara Province in southern Madagascar, including in the Special Reserve at Cape Sainte Marie.

[2][3] Megistostegium perrieri has been assessed as endangered on the IUCN Red List.

It is also threatened by wildfires..[1] The leaves of M. perrieri are locally used to treat coughs.