Family: Fabaceae
Common name: Giant sensitive plant, Creeping sensitive plant, Giant false sensitive plant, Spiny mimosa, Nila grass, Anathottawadi, Padaincha
Giant sensitive plant is a straggling or creeping bush that can quickly cover large areas of unoccupied land. They are native to South and Central America, though they have been introduced to many other continents, where they thrive in tropical and subtropical climates.
Plant characteristics
Though they are big brothers of the Touch-me-not plant or Mimosa pudica, and look very similar, though they can grow much taller, to a height of 2-3 meters with long, green, flexible stems that are square in cross-section.
Leaves of the Giant sensitive plant are compound, each leaf comprising 10-20 pairs of small leaflets that are 8-10 mm long. They look feathery and soft to touch, except for the thorns on the stem that can prick your hand if you touch them.
The stem – the main ones, and the smaller branches are all covered in small green or reddish thorns that are curved back, making it exceptionally difficult to retrieve a piece of cloth that gets stuck on it.
They can also hurt very badly. The sharp thorns are said to even hurt elephants known for their thick skins, and hence the plant is called ‘Anathottavadi’ in Malayalam.
These plants are also sensitive to touch and the leaves fold up when touched or disturbed. They also exhibit nyctinasty, the leaves folding up at night or when it is dark, a response to light that many plants show.
Flowers of the Giant sensitive plant are very pretty – small, pink pom-poms blooming at the tips of the stem in clusters, each flower having a diameter of 2-3 cm. The small center has multiple pink stamens radiating outwards giving it a fuzzy appearance and also attracting pollinators to the plant.
These flowers usually appear during spring and summer, though the plant can flower for a much longer time period.
After pollination of flowers, the Giant sensitive plant produces clusters of small fruit pods that crowd together. The fruit pods are 4-6 cm long, initially green, turning brown on maturity before opening up to release the seeds.
The seedpods also look very interesting – big clusters of plump fruits with bulges throughout its length for housing the seeds.
Giant sensitive plant seeds are oval and flattened, dispersed through water or by clinging on to animal fur. The seeds can lay dormant in the soil for up to 50 years, waiting for the right conditions to germinate.
Growing tips
It is unlikely that anybody would want to grow the Giant sensitive plant in their gardens considering how invasive they are. The sharp thorns also make them very hard to remove by hand.
If you find one in the garden, it is better to remove them quickly before they establish themselves as a colony that cannot be destroyed.
These plants need good sunlight. But they are capable of tolerating a variety of growing conditions like partial shade, poor clayey soil, drought, and weather fluctuations. In short, they can survive and thrive just about anywhere.
Giant sensitive plants do not need watering, pruning, fertilizaion, or pest control – the reasons this plant is considered very invasive.
They can self-seed and also grow very quickly, spreading over large areas. They are not eaten by grazing animals because of the thorns, which makes it even more easier for the plant.
Uses of Giant sensitive plant
These plants make excellent ground covers since they can grow and spread very quickly. When grown in slopy areas, Giant sensitive plants can help retain the nutritious topsoil, preventing it from washing away.
They are toxic and are not used for food or medicinal purposes. So they should be kept away from pets, farm animals, and from children.
Belonging to the Fabaceae family, the roots of the Giant sensitive plant has nitrogen-fixing bacteria that can convert atmospheric nitrogen to nitrates and nitrites that can improve soil quality.
Propagation
Propagation is through seeds, that can germinate very quickly in any soil, and also stay dormant in the soil for many decades before they germinate.
They can also be propagated through stems, but it is very difficult because of the thorns that can cause sharp cuts.
Photographed at: Thrissur, Kerala
