The alternate, mostly stalkless leaves of Phymaspermum acerosum are variable, long and narrowly linear, from simple to seven-segmented and sometimes channelled. Leaf dimensions are about 45 mm long and less than 1 mm wide.
A large gland-like swelling is present on the lower surface of the leaf midrib. The often-curving leaf segments may be rigid or soft and sparsely hairy, the segment tips abruptly pointed.
Pale, yellow-green flowerheads, nearly globular, can be seen in picture on a young side-branch emerging above the stem-leaves. Leaves on side-shoots appear miniaturised (Pooley, 1998; Onderstall, 1984; iNaturalist).