Walking through the Woodland on a still day, you may be suddenly enveloped in the exhilarating, surprising scent of burnt toffee. This is released by the yellowing autumn foliage of the katsura tree (Cercidiphyllum japonicum) of which there are several in this planting. The sweet scent is caused by the molecule maltol that is released as the leaf breaks down, which is indeed the same molecule released when sugar is burnt to become caramel. It is not (yet) known what purpose, if any, there is for the katsura tree to release this alluring scent.
The Oxford Botanic Garden has included this fascinating tree in their excellent Chemistry at the Garden Discovery Trail, which you can listen to via the link left.
There are only vestiges of foliage left on the trees now, but the toffee scent still lingers on the air. The pendulous selection of katsura by the stream edge becomes buttery yellow and seems to have the strongest scent; you can crouch within the bell-jar and be enveloped in this lovely autumn smell.