No, this is not what it means. It refers to species which typically have one big extension of growth per year and store their resources primarily in the vascular system (thus, this is their center of strength, not the roots, or foliage). There are exceptions to the one push of growth, notably redwoods.
No, I'd say massive storage of resources in the vascular system is his major criterion. So Thuja is grouped in extending species. Pines are not, because their major storage is in the roots. For most species in the category, those resources are invested in one big "extension" of new shoots every spring, then the tree goes back to storing resources (and producing back buds).
The shoots - or, as you put it, the woody stems.
That's what she said.
Except that is not what you said.
Yeah, as I said, the main criterion is storage of resources in the vascular system, so naming it after a growth pattern is probably not the clearest terminology, especially since some species within the group don't follow that pattern and some species outside the group do (e.g. single-flush pines). I guess 'extending species' just has a better ring to it than 'major storage of resources in the vascular system species.' Maybe they could be called 'vascular species?'
So then, everything else beyond Pines & Junipers, comes under the Elongating species category....
And how can an ordinary hobbyist distinguish where the massive storage of resources for each species is lying?
For conifers, for the most part, yes. Broadleaf deciduous are not included. Ryan is covering some deciduous topics in his live streams, but he does not offer formal courses on them.
By studying with a bonsai professional, or in a horticulture program!
The centers of strength for the categories I mentioned are: Pines - roots; Junipers - foliage; extending species - vascular system.
Ahh, the old metaphorical 'strength' and 'energy'. Pines are not real good about growing roots, just try air-layering one or to root a cutting.
I think in the case of pines, they do store carbohydrates in those thick roots. Junipers don't store a lot of carbohydrates in the foliage, they just need that photosynthetic surface area to keep the tree supplied with carbohydrates.
Carbs are stored as starch grains in living cells throughout the tree - of that I am certain. For me, where I am 'fat and fleshy' is indeed where most of my excess calories are stored. It is also true of potato plants. I am unsure about trees, but highly skeptical that and fleshy' structures are necessarily indicative of that. There are living cells mixed throughout the live-wood of all trees and I would venture a guess to store the greatest amount of starch simply because it is the biggest physical portion of any tree.
