Australian and New Zealand Gardening: TEA ROOM # 22, 1 by Stake

Stake wrote:
G'Day
I don't know if things have changed in the plant known as the Thornless Blackberry but way back in the past there was a Thornless Blackberry that had longer fruit than the thorny one and was no where near as tasty. It puzzled me as a young lad that this plant was propagated from cuttings and grew new Thornless plants but if a cane touched the ground and took root the vine from there on was thorny and any cuttings taken from there also grew thorny plants but the fruit was the longer less tasty type. I never found anyone who could explain this to me and I still don't know why. A case for "Why is it so"? Or perhaps one of our group knows why?
Photo of one of our local "Mallees" Eucalyptus foecunda.
Regards