Its fronds are 3 to 8 metres (10 to 30 ft) long, borne on brown stipes which grow paler in color towards the blade, armed with 0.6 millimetres (0.02 in) thorns.

Scattered tiny hairs are present on the underside (only) of the costae, costules, and some veins.

[1] It most closely resembles H. melanochlaena, H. repens, and H. scandens, all of which are also large with thorny stems.

[4] Schwartsburd and Prado designated a Peruvian collection by Poeppig made in 1829 as the lectotype in 2016.

[1] Hypolepis parallelogramma grows in the forests at the base of the Andes from Colombia and Venezuela south to Bolivia, at altitudes from 850 to 2,700 metres (2,800 to 8,900 ft).