Common name: The Sensitive plant
This is demonstrated when the narrow fern like leaflets are touched, they almost instantaneously fold together and the leaf stalk droops.
Sometimes this sets off a chain reaction, with several leaf stalks falling on top of one another, causing the collapse of a whole section of foliage, or perhaps the whole plant.
If left to its own devices, the plant gradually return within half an hour to normal.
This touch-induced movement of leaves is known scientifically as thigmonasty, and is thought to be a defensive mechanism against grazers.
At night, the leaves will also fold and bend in movements known as nyctonastic movements (reaction to absence of light).
Mimosa is a short-lived tender sub-shrub that is native to the upper regions of South America and is normally grown as a pot plant in the UK.
Although a perennial, it is probably best treated as an annual, and kept for one season only.
If treating it as a perennial keep it either in a warm greenhouse or in a warm room in the house during winter months.
They can grow to 600mm (24") high, the flowers that appear in July and August form in clusters of five to eight fluffy, ball-shaped pale mauve-pink flowers on short stalks growing from the leaf axils.
Plants flower better and the foliage is more attractive when the roots become pot bound.
Keep the plants moist at all times.
Week 9: Sow seeds in pots/trays of seed compost and germinate at a temperature of 21°-24°C (70°-75°F).
Germination should take two to three weeks.
Week 14: When they are large enough to handle, prick out the seedlings individually into 75mm (3") pots of potting compost.
Week 20: Pot up into final 150mm (6") pots of potting compost.
Insert a split cane at this stage for support.
Week 24: Apply a weak liquid feed at intervals of two weeks from now until September.
Keep the plants in a warm well-lit position, but give light shading during the hottest months.