Common name: Winter Cassia, Butterfly Bush 雙莢槐 雙莢決明
Family: Fabaceae
Origin: Tropical America
Location: Robinson Road

This tree is planted on the side of a residential building, but I find the red wall of the next building provided a better backdrop, so I used that as the background.

A small tropical American species of Cassia growing to a maximum height of 3 m, with smooth, hairless branches and the whole tree often with a graceful willowy appearance.

The leaves are alternate, pinnately divided with 3 to 4 pairs of leaflets and no odd terminal one. The leaflets are 1 - 4 cm long, the shape varies from almost round to obovate (the widest part toward the leaflet apex) and in either case the apex is rounded and in some leaves has a small notch in the tip. Between the lowest pair of leaflets there is a gland on the leaf axis. The leaf stalk is 3 - 4 cm long.

Flowering late Autumn. Flowers are in clusters in the leaf axils, the clusters usually being longer than the leaves and very abundant. The calyx is tubular, with 5 longish teeth, petals are five, bright yellow, free and overlapping. Fertile stamens are seven, very unequal in size. The ovary is superior and one-celled.

The fruit is a pod which is cylindrical, rather papery, 6 - 16 cm long, curved, somewhat sausage-shaped, containing numerous shining brown seeds.