Another angle, which might in part have been the intent of the interviewee in question, is that many plants are dependent on environmental conditions, including plant community structure, which are dependent on fire, at least in a natural ecological context. We know that in southeastern U.S. pine-grasslands that are large percentage of the of several hundred species of herbs disappear upon excluding fire for several years, some sooner than later, as well as many species of animals that depend on them. This is because woody plants that would otherwise be topkilled rapidly grow and outcompete herbs through root competition and shading, in addition the removal of fire as a reproductive cue for reproduction and a means to provide bare mineral soil for seed germination.
That aside, I am pretty unapologetic about saying that certain plants are "fire dependent" when talking about this ecosystem. That is not to say that you could not get the plant to survive and reproduce in a greenhouse if you knew what specific environment and cues were required, but in an ecological context it appears to be true that populations of certain species depend on fire for their survival, at least there is no other process that we know which would take the place of fire's function in that population's survival. A well studied case is that of wiregrass (Aristida stricta), which for a long time was thought (even if illogically) to no longer sexually reproduce, since no one had ever seen it flower and produce seed. However, at the time controlled burns were annually applied in the winter throughout much of the region, preempting lightning initiated fire later in the growing season. It was discovered later that burning (and perhaps lightning-initiated or accidental fire) in the growing season, especially May-June, did cause the grass to produce seed, and this corresponded to the period when lightning-initiated fires were and still are most common. Grazing does not seem to have the same effect of fire on this species with regard to reproduction. Is there any set of circumstances in which it would flower without fire? Probably. Would that set of circumstances have occurred historically without human intervention (it was around before Native Americans)? Probably not, or extremely rarely. Would wiregrass be one a common grasses throughout the eastern half of the southeastern U.S. Coastal Plain without fire? Absolutely not. Thus, for all intents and purposes, in an ecological rather than theoretical or physiological context, I would say it is a fire-dependent species. Kevin Robertson
