These two species are very hard to separate, and require a look at the leaves near the base of the plant, which are broad with toothed to lobed margins in dentata and narrower with usually smooth margins (rarely a few irregular teeth) in gibbosa. As the lower leaves have often been shed by the time the plants flower, ID can be tricky. L. dentata frequently appears after fire, flowering within 6 months post-fire.
Lobelia dentata/gibbosa is listed in the following regions: