Poa foliosa is a perennial, dioecious grass growing as densely clumped tussocks up to 2 m in height.

The tussocks arise from short, woody stolons, with the shoots covered at the base by the fibrous remnants of sheaths.

[5] On Macquarie Island's coastal terraces and slopes it grows in mixed stands with Stilbocarpa polaris where the drainage is good, and along the borders of streams.

It forms a tall tussock grassland along the beaches above the high-water mark, as well as patchily on the island's plateau in sheltered and relatively exposed sites.

[4] In both 2009 and 2012 it was deemed to be "At Risk - Naturally Uncommon" under the New Zealand Threat Classification System,[5] and this New Zealand classification was reaffirmed in 2018 (due to its restricted range), with a further comment that it was safe overseas.