Classifications
A Classification is an arrangement of taxon in a tree structure. A tree structure arranges taxa in a parent/child relationship. The tree has elements that hold the position of a Taxon Concept, and it's metadata in an arrangement of taxon that we refer to generically as a tree.
A tree changes over time as our understanding of the taxa changes, so a tree can have many versions. Versions of a tree are Publications that can be referenced or cited. You can cite a published tree (version) using an identifier for the tree version or using an identifier for a tree element. This will return the element and then entire tree in the context of the published tree. Each version of a tree is immutable, i.e it doesn't change. You can cite a tree element with confidence that it will not change over time, while being able to trace the history all the way to the current placement.
Available Trees
The Australian Lichen Checklist (ALC) is a list of the accepted scientific names for the Australian lichen, both native and introduced, and includes synonyms and misapplications for these names. The ALC covers all published scientific algae names used in an Australian context in the taxonomic literature, but excludes taxa known only from cultivation in Australia.
