Final answer:
The vertical length on a phylogenetic tree usually does not indicate time, but rather the order of evolutionary events, unless a timescale is specified. Branch lengths denote the sequence in which traits or species evolved.
Step-by-step explanation:
On a phylogenetic tree, the vertical length typically does not indicate the amount of time that has passed. The length of a branch reflects only the evolutionary order unless the diagram explicitly states the timescale. For example, a long branch does not necessarily mean more time has elapsed compared to a short branch. Phylogenetic trees show the sequence of evolutionary events and relationships, such as which traits evolved first or how species are related, but they do not necessarily depict how much time passed between these events.
Key features include the tree's root, which indicates a common ancestor for all organisms represented, and branch points, which show where lineages diverged. A basal taxon is a lineage that evolved early and is unbranched, while sister taxa stem from the same branch point. It's important to understand that while these branches show evolutionary relationships, they do not imply that one group of organisms gave rise to another directly.