Pigeon Breast defect in Bonsai design

In an article posted by Brent Walston titled 'The ‘Rules’ of Bonsai', Brent states the below statement about a defect in the trunk called 'pigeon breast':

"Curves in trunk should not result in ‘pigeon breast’ (roundness toward viewer)."

I need to learn more about this defect from someone more experienced in this forum. Does this mean that only curves and not sharp turns like in a driftwood or shari qualifies as pigeon breasted? Also, Brent did not mention whether the defected curve occurs in the lower half or the top half of the tree.

Input on this topic is most appreciated.

OK. Picture this: One of those Chinese mass-produced elms with a massive S-curved trunk.





Now, assume that ugly bend to the right was the "front" of the tree and was facing the viewer. THAT would be a "pigeon breast." The top part of the "S" is bending toward the viewer, which is OK. It is the lower trunk that is the (or rather ONE of the) problem(s) with this extremely unattractive tree. UGLY tree courtesy of a commercial site on Google images.

Thanks Jim,

That really clarifies what Brent means by 'pigeon breasted'. That leads to two more questions:

- In case of some conifers or lingnan style deciduous, if that bend (that you described above) is actually a sharp turn, will that be a defect?
- Does it matter at what height of the tree that bend/turn becomes a defect?

Thanks again for your input. I look forward for your response.

I'm not certain what you are asking. in that illustrated tree, that first turn is about as sharp as a turn can get. That certainly is a defect -- though there's not much in that tree that is not a defect.

Perhaps you mean like this:



Which, I suppose, could be the start of a cascade bonsai, but still probably a not stellar one.

Thanks Jim,

That is what I meant. Thanks for your picture examples, they really help.

Some trees are very contorted, with many twists and turns. If a change of angle or viewing position improves the movement of the trunk line, I see no problem with this "Pigeon breast" front.