touch-me-not
noun
ˈtəch-mē-ˌnät 
: either of two North American impatiens growing in moist areas: such as
a
: one (Impatiens capensis) typically having orange flowers spotted with reddish brown
b
: one (I. pallida) having typically yellow flowers sometimes spotted with reddish brown
Word History
Etymology
from the bursting of the ripe pods and scattering of their seeds when touched
First Known Use
1659, in the meaning defined above