Tetramolopium capillare is a sprawling shrub with stems measuring 50 to 80 cm (20 to 31 in) long and covered with many glands when young. The very firm, stalkless leaves are involute and are usually 13 to 25 mm (0.5 to 1 in) long and 0.4 mm (0.01 in) wide. Flower heads are situated singly at the ends of stalks 1 to 3.5 cm (0.4 to 1.4 in) long. Located beneath each flower head are 45 to 50 bracts, arranged in a structure 3 to 4 mm (0.1 in) high and 7 to 10 mm (0.3 to 0.4 in) in diameter. In each flower head, 30 to 50 white, male ray florets, 3.5 to 4 mm (0.1 in) long and 0.6 to 8 mm (0.02 to 0.3 in) wide, surround 15 to 25 greenish yellow tinged with red, functionally female florets about 3.6 mm (0.1 in) long. The achenes (dry, one-seeded fruits) measure 2 to 2.6 mm (0.08 to 0.1 in) long and 0.7 to 0.8 mm (0.03 in) wide and are topped by a white pappus comprising a single series of bristles 1.9 to 2.1 mm (0.07 to 0.08 in) long. Tetramolopium capillare differs from other species of the genus by its very firm leaves with edges rolled under, its solitary flower heads, the color of its disk florets, and its shorter pappus. It differs from Tetramolopium remyi, with which it sometimes grows, by its more sprawling habit and the shorter stalks of its smaller flower heads