Monkey grass is not poisonous. It is considered non-toxic for humans and dogs, but it is possible that it could trigger a reaction following ingestion. Small children may choke on monkey grass if they happen to ingest it. Consuming large quantities could result in an upset stomach.
Monkey grass is a nickname used in the American South for two different types of non-toxic grasslike evergreen flowering plants native to Asia: mondo grass (Ophiopogon japonicus) and plants in the genus Liriope. Both are especially well-suited for use as ground cover or for creating edging or borders along garden beds or walkways. Both mondo grass and lirope are best suited for areas with partial to full shade, and both have variegated cultivars. Liriope varieties range from 10 inches to 2 feet in height, while different varieties of mondo grass reach their mature height from 2 inches to 12 inches.