Larsenianthus arunachalensis grows as an evergreen, perennial herbaceous plant that can reach heights of up to 1.5 meters.

The hard, fibrous rhizomes give off a light scent, are up to 1.9 centimeters thick and have a pale brown colored interior.

[2] The inflorescence grows upright at the tip of leafy stems and can reach a total length of up to 90 centimeters.

The calyx tube is cut 5 to 6 millimeters deep on one side and is hairy, with the hair becoming thicker towards the tip.

The red petalsare fused into a corolla tube that is 3.2 to 3.3 centimeters long and about 3.5 millimeters in diameter at the top.

The upper corolla lobe is slightly downy on the inside with single-celled, branched trichomes hairy and bent back.

[2] Larsenianthus arunachalensis is known from the place where the type specimen was found on Lohit, near Lalpani, in the state of Arunachal Pradesh in northeast India.

One finds Larsenianthus arunachalensis in dense stands of wild occurring banana ( Musa spp.).

The specific epithet arunachalensis refers to the Indian state of Arunachal Pradesh, in which the type material was found.