Lobelia neglecta grows short-stalked to about stalkless, mostly alternate leaves. The leaves are oblong to slightly ovate, or wider near the base. The leaf tips are rounded to obtusely pointed. The margins are entire, sparsely fringed in long, spaced hairs, and usually rolled under. The upper surfaces are bright green, some in picture yellow green. The blades may be shiny although rough and slightly bulging with midribs sunken. The lower leaf surfaces are paler and hairy. The leaves are about 1 cm long and 4 mm wide.
The stems are purplish grey with stubbly white hairs in picture (Euston-Brown and Kruger, 2023; Bond and Goldblatt, 1984; iNaturalist).