Traits, such as resprouting, serotiny and germination by heat and smoke, are adaptive in fire-prone environments. However, plants are not adapted to fire per se but to fire regimes. Species can be threatened when humans alter the regime, often by increasing or decreasing fire frequency. Fire-adaptive traits are potentially the result of different evolutionary pathways. Distinguishing between traits that are adaptations originating in response to fire or exaptations originating in response to other factors might not always be possible. However, fire has been a factor throughout the history of landplant evolution and is not strictly a Neogene phenomenon. Mesozoic fossils show evidence of fire-adaptive traits and, in some lineages, these might have persisted to the present as fire adaptations.