Recently I gave a presentation at the New Zealand Arboricultural Association conference, I pointed out that stress is an external force or an emotional condition, and that it is incorrect to say a tree is ‘stressed’ when not talking about external forces. Trees don’t get emotional.

I wanted to point out that response growth can’t be all bad, that if a tree is able to respond then it must be healthy enough to respond (and if a tree can’t respond, it is us that should be stressed). It was a simple enough message, and one I think I was able to convey.

I boldly suggested that what we call ‘stress’ should be called ‘stimulation’ – there is a change in the balance of growth regulators that initiates growth in one form or another; growth in response to stimulation.  Shortly there-after I was outside and I came across these and I began to wonder if stimulation really was the best choice of words…

It turns out that they are woody structures that grow on Ginkgo trees called chi-chi. They are a type of adventitious growth complete with vascular cambium and secondary xylem – eventually they become roots. They are not uncommon, on Ginkgo although I’ve never seen them before.