The colour scheme here is relatively subdued, with a brownish tint being merged into the grey background, alongside the sharp, dark tones of line which construct our imaginary tree. The forms by now are particularly hard to decipher - we have travelled a long way from his earlier piece of Gray Tree, where trunk and brunches were much more obvious. Perhaps two diagonal lines which come in from the top represent the top of the tree, where the branches reach out furthest, and the colours get slightly darker along the bottom, where the shadow would have been. We are really guessing based on his other tree paintings as to what has been depicted here, and this work also is marginally more abstract than a similar piece, Flowering Apple Tree.
The artist, later on in his career, created Neoplasticist paintings where abstract shapes were created with crossed lines and they would then be filled with primary colours. A good example of that would be Composition with Red, Blue and Yellow. In the case of this tree painting, the artist is a long way from that level of abstraction, but we can see early signs of techniques like that here.
Where the lines cross here, which essentially are the branches of the tree, rather than simply showing the background through this window of space, the artist actually places different tones within each area. This is not directly what he would have seen in reality, but he chooses to produce a grid of colour based loosely on the original positions of the tree branches and trunk. It is an early movement towards what would arrive later but can only be appreciated if you study the painting up close.