[2] Phyllostegia haliakalae is a viny suberect herb plant, with forward-bending hairs on its stems.

[3] Phyllostegia haliakalae is endemic to the Hawaiian Islands, primarily the islands of Maui (eastern portion), Lanai, Molokai, and recently Oahu, where the species grows in mesic forest, wet forest, wet cliff, and dry cliff ecosystems.

[3] Phyllostegia haliakalae has had up to six synonyms in the past, which is quite a lot compared to other species in the genera, and other plants of Hawaii.

The species was originally misclassified, being assigned to Phyllostegia pilosa, and afterwards, Pyllostegia mollis, until it was reassigned to its own appropriate taxon.

[4] There are no currently listed uses for Phyllostegia halaiakalae because of its endemicity and rarity, although there may be a few older uses before the drastic population decline.