It is also known from British Columbia, where there is a single occurrence in the mountains above the Okanagan Valley.

[1] This fern produces several narrow, erect lance-shaped leaves 10 to 35 centimeters long.

Each leaf (frond) is made up of many oval leaflets (pinnae) which are overlapping, folded, and twisted such that the leaves may appear almost cylindrical in outline.

Leaflet margins are entire or bluntly dentate.

[2][3] Though it grows in very restricted areas, P. lemmonii can be locally very abundant.