September

In late summer, you may be amazed by a lovely purplish-red flower as you walk around ponds, marshes or wet fields. This is Touch-me-not (Impatiens chinensis). You will see this plant in the middle portion of the Stream Walk and in the Wet Zone of the Wetland Discovery Centre.

Touch-me-not is a common wetland plant in Hong Kong. It is an annual, which means that it completes the cycle of germination, growth, flowering, seeding and wilting in one year.

Touch-me-not belongs to the family Balsaminaceae. Most flowers in this family have a special petal-like structure modified from the sepal, called 'labellum'. On top of the labellum there is a curved, long and narrow 'spur', with nectar glands inside. The shape and structure of spurs differ among different species of Balsam, so only insects with their mouthparts fitting the spurs can suck nectar from the flowers, pollinating in the process. Therefore, each species of Balsam attracts only a certain species of insect. The differentiation of the spur structure ensures pollination occurs only between the same species of Balsam, hence reducing wastage of pollens.

The long spur resembles the beak of birds. Petals resemble the body and wings of birds, giving the flower it's attractive bird-like appearance.

Besides the upright stems that bear flowers and leaves, it also has horizontal stems growing just above ground. Roots grow from the nodes and give rise to new plants, helping the plant to spread rapidly. This is an adaptation of the wetland plant in response to the environment.

Touch-me-not is 30-60cm tall, and it has fleshy and juicy stem. Its leaves are elongated, opposite, and with slightly toothed margins. The leave veins are not conspicuous. Why the name 'Touch-me-not'? It is because when the pod-shaped fruits mature, the pods burst open upon touch, shooting its seeds around. Its Latin name 'Impatiens' means it resembles an impatient person who cannot wait to burst.

A small plant with complicated structure - Touch-me-not is not to be neglected!