Do bonsai (or trees) with muscular trunks (e.g., American hornbeam) have
less likelihood of transporting nutrients laterally?

Muscles have nothing to do with it. It depends on the number of
pores in the sides of the elements, compared to pores at the ends.
Gymnosperms (pines, ginkgos, etc.) have a more primitive hook-up of
vascular elements, and I'd expect them to have have more lateral
spread (relatively speaking) than modern angiosperms (maples, beech,
etc.), which have very specialized xylem elements. There are
actually books devoted to wood anatomy (check the nearest Forestry
school).
--
Nina Shishkoff

Frederick, MD

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