The quadruple U-shape is a variant of the double U-shape.
A quadruple U-shape requires significantly more time and craftsmanship to grow than a double-U-shape.
The Quadruple U-shape is a complex espalier that requires years of grower planning. Before the cultivation starts, the grower must make a design drawing. The grower must then implement this design in a targeted and consistent manner for many years. Design errors in complex palm shapes are almost impossible to correct afterwards.
Some nurserymen choose to keep the horizontal parts ‘bare’, because they naturally bear less fruit and it takes relatively more work to produce fruit.
Very difficult and time consuming (so expensive) to propagate. On the other hand, fairly easy to maintain.
Verrier palette and Gaucher palmet are a lot easier to grow.
Suitable for pear, apricot, apple.