What is "tearthumb"

n. Any of a group of annual vining plants within the genus ''Polygonum'', with small sharp spines covering the stems.

Tearthumb is a common name for a group of annual vining plants within the genus Polygonum, notable for the small, sharp spines covering the stems, which "tear the thumb", leading to the common name. The spines are used for climbing, and can puncture the leaves of plants being used as supports.

Species called tearthumb include:

• Polygonum arifolium (Halberd-leaf tearthumb) -- North America
• Polygonum perfoliatum (Mile-a-minute) -- Asia, but invasive in North America
• Polygonum sagittatum (Arrowleaf tearthumb) -- North America

Category:Polygonaceae