Desmodium gyrans is well known as the “Telegraph Plant” and famous for its movement. The small lateral leaflets will rotate on their axis, moving in jerky motions under the slightest influence of touch, sunshine, warmth or small vibrations. At night they droop downwards.

The plant is native to Asia, easy to raise from seed it will soon make a small shrub, but it is not hardy, preferring indoor temperatures of 22 to 35*C (71 to 95*F). The soil must be kept consistently moist, without drying out between watering. The perfect place for this plant is a light shade, since a direct sun is far too strong for its delicate nature.
The foliage is very simple; it has a very airy look to it with delicate stems that bear the leaves. It is a fascinating plant, perfect for children to grow and have fun with, the plants really do 'dance' in their own way.

A study done in 1998 says the movements are caused by the swelling and shrinking of motor cells in special organs buried deep within the leaves. The movement of water molecules causes the motor cells in the leaves to shrink or swell and, as the water enters and exits, the plant's leaflets twitch. Experts say there is no particular sound it reacts to, though some believe that it does not respond well to electronic sounds.

Sowing:
Sow indoors at any time of year.
Soak the seeds in a container of warm water for a day or two.
Fill small pots or trays with a moisture retentive compost, (Mix of humus, garden soil and a little bit of sand.) and stand in water, then drain.
Plant the seeds at a depth of 1cm (3/8 in) and cover the container with clear plastic wrap or lid. Place the pots in a warm place, ideal germination temperatures are 24 to 27°C (75 to 80°F)
Germination of the seeds can start in 10 days, with the majority germinating in 30 days. They may take up to 90 days, so don’t be discouraged.

Cultivation:
Remove the plastic cover once they have germinated. The seedling leaves will not move. About three weeks later, real leaves will appear and will move.
Once they are well established, the plants should be transplanted to 13cm (5in) pots of standard potting mixture.
The soil must be kept consistently moist, without drying out between watering.
Being a member of the pea family, Leguminosae, it has the ability to fix nitrogen from the air and is therefore adaptable to most soil types, including those of poor quality.

Plant Uses:
Greenhouse, conservatory or house plant, Children.

Of Interest:
This extraordinary plant came incredibly close to extinction but recent research by Dr. Pradit Kampermpool at the Kampermpool's plant nursery in Udon Thani Province, in tropical northern Thailand, has secured the continued existence.
in 1880 Charles Darwin published The Power of Movement in Plants. It was his last work before his death and describes this plant in detail.

Nomenclature:
Darwin called the plant Hedysarum. It was first described in 1779 by Dutch physician and naturalist Maarten Houttuyn, who named it Hedysarum motorium.
Modern botanists call it either Desmodium gyrans or, more correctly these days, Codariocalyx motorius;
The species name is derived from the word "gyration".
Its common name is Telegraph plant or Semaphore plant -- after the leaf movements, which resemble semaphore signals or Morse code.
Dr. Kampermpool simply calls it 'The Plant'.

Members of this genus are among the few plants capable of rapid movement. As far as we know the only four plants that show any leaf sensitivity movements are: Desmodium gyrans, Mimosa pudica the sensitive plant, Venus Fly Trap, and Averrhoa carambola the star fruit tree. These types of movements have been termed seismonastic movements. Darwin believed, the movements shook water droplets from its leaves following a heavy rainfall.
A study done in 1998 says the movements are caused by the swelling and shrinking of motor cells in special organs buried deep within the leaves. The movement of water molecules causes the motor cells in the leaves to shrink or swell and, as the water enters and exits, the plant's leaflets twitch. Experts say there is no particular sound it reacts to, though some believe that it does not respond well to electronic sounds.