Grows on the sunny edge of a raupo swamp. Lax, openly branched herb with distant whorls of leaves, on a square stalk. Leaves are narrow, about 7 mm long by 1 mm wide even near the base of the plant where they are said by NZ Flora to be often bigger . NZ Flora says G. debile is 0.8 -1.5 mm wide, with palustre 0.7 to 4.5 mm wide, so I suspect debile.

The white flowers are in loose panicles comprised of cymes of about 5-10 flowers as for debile, but not 3-7 flowers as for palustre, i.e. there were often 8 or more flowers, sometimes 11.