The specific epithet aquaticum refers to this species' typical habitat.

Linear leaves, about 20-100 per plant, are scattered along the elongate, glabrous stem.

S. aquaticum is only known from its type location in northwestern Northern Territory of Australia.

Its habitat is recorded as being a Melaleuca viridiflora swamp, growing in shallow water at a depth of around 7 cm.

S. aquaticum is most closely related to S. fissilobum but differs mostly in the leaf shape.