Biophytum sensitivum Seeds | Little Tree Plant
LATIN NAME: Biophytum sensitivum
COMMON NAME: Little Tree Plant
Plant Profile
Biophytum sensitivum is a small annual or short-lived perennial with a rosette of pinnate leaves on a short, woody stem, and it moves when it is touched. The leaflets fold upward in pairs along the midrib within a minute of a stimulus, and the whole leaf droops on its stalk. At night the leaves close on their own, and they reopen after sunrise.
The plant reaches about twenty centimetres, with a tuft of small orange-yellow flowers at the top, and it seeds itself freely in a warm greenhouse. It is native to the wet tropics of South Asia, from India to southern China and through South-East Asia, and it grows in damp shade on forest floors and along streams. It is one of the few plants that responds to touch as quickly as the better-known Mimosa pudica.
Science & Biotechnology
The movement is driven by a pulvinus, a swelling at the base of each leaflet and of the leaf stalk, where motor cells change their volume by moving potassium and water across their membranes. When the leaflet is touched, an action potential travels along the vein and the cells on one side lose water, which collapses the hinge. The whole response takes about a second for the leaflets and a few minutes for the stalk.
The same mechanism responds to rain, to wind and to darkness, and it is thought to protect the leaf from damage and from water loss. The plant also shows a daily rhythm that persists in constant conditions, which means an internal clock gates the response: leaves that have been closed by touch will not reopen until the clock allows it, even if the stimulus is removed.
Uses & Benefits
In Ayurveda the plant is called pakhan bet and is used for wounds, for inflammation and for diabetes, usually as a paste of the leaf or as a decoction of the whole plant. Extracts have shown antioxidant and anti-inflammatory activity in vitro and in animal models, and there are no controlled human trials.
The plant is grown as a curiosity and as a teaching subject, since it is easier to raise in a pot than Mimosa pudica and it demonstrates the same phenomenon with a smaller plant. It is sold in the houseplant trade as a novelty, and it is used in school biology classes in India.
Growing from Seed
Seed is tiny and should be surface-sown on a moist, peaty mix at 22 to 25 degrees, with light, since it needs light to germinate. Germination is in two to three weeks, and the seedlings are delicate until the first true leaves open.
The plant wants bright, filtered light, constant moisture and high humidity, and it resents dry air and cold water. Keep it in a warm greenhouse or in a sealed container, water from below, and let it self-sow, since the parent plant declines after flowering. It is not frost hardy and it should be treated as an annual in a temperate climate.
Our Take
A small, quick-moving plant that is easier than Mimosa and just as good for showing how a leaf decides to close.
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