Fire pink is an erect form, 2-8dm tall, with glandular stems with fine, short hairs. It has an open, 7-10 flowered inflorescence, a broadly tubular calyx, 18-22 mm, crimson petals with 3mm tubular appendages, linear-oblong limbs, 15-22mm, 2-lobed, and 3 styles. Its fruits are capsules dehiscent by 6 teeth, seeds are roughened. Leaves are opposite and entire. Basal leaves are oblanceolate or spatulate, petiolate, 4-10cm long by 8-18mm wide, cauline leaves are in 2-4 pairs, sessile or nearly so, to 30cm long and 3cm wide.
It can be distinguished by its bright red petals that are notched at the tips.