Meaning of touch-me-not

(noun) North American annual plant with usually yellow or orange flowers; grows chiefly on wet rather acid soil

Mediterranean vine having oblong fruit that when ripe expels its seeds and juice violently when touched

prostrate or semi-erect subshrub of tropical America, and Australia; heavily armed with recurved thorns and having sensitive soft grey-green leaflets that fold and droop at night or when touched or cooled