1. A weedy perennial with tough wiry stems and purple flowers; native to Europe but widely naturalized
   - lesser knapweed, black knapweed, hardheads

Type of: knapweed

• scale down
• scale factor
• scale fern
• scale insect
• scale leaf
• scale moss
• scale of C major
• scale of measurement
• scale up
• scale value
• scale wax
• scaled
• scaleless
• scalelike
• scalene
• scalene muscle
• scalene triangle
• scalenus
• scalenus syndrome
• scaler
• scaley
• scalic
• scaliness
• scaling
• scaling ladder