It has a single stiff, erect leaf and up to twenty scented, greenish-brown or reddish-brown flowers crowded on a stout spike.

The lateral sepals are about 6 mm (0.2 in) long, joined for most of their length and form the uppermost part of the flower.

The labellum is sharply curved near its middle, often has a wavy edge and is covered with a raised callus.

[7] In 1944, Herman Rupp described P. tadgellianum as a synonym of P. alpinum in his book Orchids of New South Wales[8] but in 1996, David Jones reinstated P. tadgellianum as a common species found in south-eastern Australia and described P. alpinum as a species restricted to Tasmania.

In Tasmania it is found only near Cradle Mountain and near Bastion Bluff in the Great Western Tiers.