I have been listening to Ryan Neil at Mirai live. He talks about elongating species. Have you heard of this term in your bonsai experience? and what is the definition of it?
I believe he uses this terminology to describe single flush conifer species as opposed to multi flush conifer species. One reason for separation in his course material is the way they respond to various refinement techniques.
Fir, spruce, redwood, bald cypress, hemlock and cedar are common examples. I haven’t heard the term elsewhere.