The maturity level for each note is represented by plant icons at different stages of growth.
Seedling
Seedlings ( ) are thoughts that have barely begun. Perhaps they were jotted down in a hurry or show only a brief amount of what I have thought about the subject so far.
Sapling
Saplings ( ) have a substantial amount of content, but still need a lot of work. Coherence and patterns are only beginning to emerge.
Tree
Trees ( ) are well-developed thoughts/essays/expressions that shouldn't change much, except for some editorial improvements.
Withered
Withered notes ( ) are notes that express outdated views (wholly or partially), but are kept for historical reasons. For partially outdated notes, warnings will be included whenever appropriate.
Stone
Stones ( ) are notes exported/extracted from other media (for example, highlights and reading notes). Growth is irrelevant to these notes.
Landmark
Landmarks ( ) are notes that allow us to navigate easily (for example, collections of books or writings).