from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A poisonous shrub (Karwinskia humboldtiana) native to Texas and Mexico, having small greenish flowers and black fruits.
from the GNU version of the Collaborative International Dictionary of English
- n. A low rhamnaceous shrub (Karwinskia humboldtiana) of the southwestern United States and Mexico. Its berries are said to be poisonous to the coyote.
Typically cited are triangular shapes on the tortoises 'shells, the occasional purple coloring of nopal coyotillo (Opuntia violacea), and the large size of human individuals in the Zone.
The claims of mutations refer to natural phenomena; the triangles are a normal pattern variant in the Bolson tortoise populations and the pads of nopal coyotillo turn a shade of violet during a dry spell.
You can hike for miles and never encounter the coyotillo shrub, whose berries cause a slow but deadly paralysis.