The Himalaya and the Thornless
At the left, a typical stem of the Himalaya, which will be seen to be relatively slender and frail in contrast with the strong, sturdy stem of the Thornless, shown at the right. Thornless blackberry also shows improved leaf formation. Both plants are very vigorous and rapid growers.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 6 Chapter 1