Indicator plant

An indicator plant is a plant whose presence is highly associated with certain harsher growing conditions such as poor soil, compacted soil, or soil high in calcium carbonate. These plants are usually tolerant of these conditions where other plants are unable to grow.

Dandelions, for example, have a thick taproot and grows well in compacted soil. Overtime these roots help to loosen the soil which allow other plants to grow alongside and eventually out compete the dandelions through succession.