The Sensitive Plant is a prickly member of the pea family whose leaflets fold shut one after another when touched, while the whole leaf droops; the leaves reopen minutes later. Native to tropical America, it is grown in the US as a houseplant curiosity and also grows wild as a weed in warm Southern states, Hawaii, and Puerto Rico. It is also called shameplant or touch-me-not.
Appearance
- Growth form
- A short-lived perennial, upright to about 1–1.6 ft (30–50 cm) or sprawling with stems up to 5 ft (1.5 m) long. The stems are prickly.
- Leaves
- Feathery compound leaves; leaflets fold when touched, shaken, watered, or warmed, and also close at night.
- Flowers
- Fluffy pale pink to lavender balls about 3/8 in (8–10 mm) across. Each flower lasts less than a day.
- Fruit
- Clusters of flat, bristly-edged pods 3/8–3/4 in (1–2 cm) long that break into one-seeded segments.
Look-alikes
Sunshine mimosa is a Gulf Coast native that lies flat as a mat-forming ground cover, with pink flower heads that look oversized for the plant. Sensitive plant stands taller and has prickly stems.
Why they get mixed upBoth have pink pom-pom flowers and leaves that fold when touched.
Where it lives
- Typical habitats
- disturbed ground
- roadsides
- pastures
- pots and gardens
- Range
- Native to Central and South America and the Caribbean; now a weed throughout the tropics. In the US it has been recorded in many Southern states (including Florida, Louisiana, Texas, Alabama, Mississippi, Georgia, and North Carolina), Hawaii, Puerto Rico, Guam, and the US Virgin Islands.
- Preferred conditions
- Full sun and poor, well-drained soil. It can't take shade or frost.
Life cycle
- Seed dispersal
- Bristly pod segments hitch rides on clothing and animal fur.
Growing it
- Care
- Usually grown from seed as a houseplant curiosity or summer annual; rough or repeated handling makes the leaves close faster.
- Toxicity
- Contains mimosine, a toxic compound. In Hawaii, the local form is reported to be toxic to livestock.
Conservation
- IUCN Red List
- LCLeast ConcernLow risk of extinction
- Threats
- A serious weed of crops and pastures in the tropics; its prickles make hand-pulling painful, and dry thickets can become a fire hazard.
Culture and stories
- Culture and stories
- The folding is powered by a swollen joint at the base of each leaflet called the pulvinus, which loses water when an electrical signal arrives.
- In plant-memory experiments, potted plants dropped again and again stopped folding, and remembered the harmless drop for at least 28 days.
More species to explore
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