Why wouldn't all plant species in the wildlife sanctuary be found in the dichotomous key?

Not all plant species in the wildlife sanctuary may be included in the dichotomous key because the key is often based on a specific selection of species that are common or easily identifiable. Additionally, some species may not have been studied or documented adequately, leading to their exclusion. Variability in plant populations, such as hybrid species or local variations, can also mean that not every species is represented in the key. Lastly, the key may focus on particular ecological or geographical areas, leaving out species found in other habitats within the sanctuary.