Cercidiphyllum japonicum, known as the katsura (from its Japanese name カツラ, 桂), is a species of flowering tree in the family Cercidiphyllaceae native to China and Japan. It is sometimes called caramel tree for the light caramel smell it emits during leaf fall.
The tree is deciduous and grows to 10–45 metres tall, with a trunk diameter of up to 2 metres (rarely more).
The shoots are dimorphic, with long shoots forming the structure of the branches, and bearing short shoots from their second year onward. The leaves are produced in opposite pairs on long shoots, and singly on short shoots; they have a 1.4–4.7 cm petiole, and are rounded with a heart-shaped base and a crenate margin. Leaves on short shoots are larger, 3.7–9 cm long and 5–8.3 cm broad, and those on long shoots smaller, 3.2–4.5 cm long and 1.9–3.2 cm broad. The leaves turn a variety of pinks and yellows in autumn, and sometimes have a distinctive caramel scent when in fresh autumn colours. The flowers are inconspicuous, produced in early spring among the opening leaves, with male and female flowers on separate plants (dioecious). The fruit is a cluster of two to four follicles 1–1.8 cm long and 2–3 mm wide, each follicle containing several winged seeds.
The species is listed as Endangered in China, but overall (including Japanese populations), is classified as being Lower Risk. The Chinese populations were sometimes distinguished in the past as Cercidiphyllum japonicum var. sinense Rehder & E.H.Wilson, but this is now generally regarded as not distinct from the type. Several different cultivars are grown, including 'Aureum', 'Heronswood Globe', and 'Ruby'.