What is a perennial plant?
To be able to answer my question, I need to make sure I understand the terms first. When I came up with my question, I imagined perennial plants - like the ones in my garden - to be separate from trees. Of course there are differences between these plants and trees, but both would be considered perennial. I started with some general research online and came across a reliable online encyclopedia (Britannica) that gave me a general idea of what a perennial plant is. The key features of a perennial plant are, one, that the plant lives for several years, and two, that new growth develops from an area of the plant that survives across all seasons.
This made me wonder if evergreen plants would be a perennial. They survive multiple seasons and develop new growth from the part that survives (any part), so they seem to fit the bill. This was not how I understood perennial plants before though. I did some more searching online and found the website of the University of California Master Gardeners which confirmed evergreen plants are perennials. I found it helped to chart how I was thinking about it before and after:
I remember for many years I struggled to remember whether perennial or annual plants were the ones that came back year after year. My mind wanted annual plants to be ones that came back year after year because normally when we talk about annual events, we mean ones that occur year after year. Obviously it's more about the fact that they have to start fresh year after year.
Clarifying the definitions felt good. It feels like a small success to understand something I previously took for granted, and just barely knew the terms for.
Resources:
https://www.britannica.com/science/perennial
https://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=15639
https://forums.botanicalgarden.ubc.ca/threads/annual-perennial-evergreen.68358/