Family: Urticaceae

An invasive weed that often spreads as a contaminant. Its native range Native to Central and South America, the artillery plant thrives in tropical climates. The first collection was in Oahu in 1925. Although it is in the horticultural plant trade, it is a major pest of potted plants and cultivated gardens in Hawaii. Another common name, rockweed, describes its tendency to grow in masonry, hardscapes, rock walls, and concrete cracks. 

Artillery plant prefers shaded places but will grow in full sun, especially in irrigated places. The seeds are spread by birds and animals externally, and if eaten, they survive passage through the gut. 

It produces by seed and vegetatively. When removing it from undesirable areas, ensure every piece of root and stem are taken out. Artillery weed can grow from a small root or stem fragment. Use a layer of mulch to discourage growth.

Description and Dispersal:

• An herbaceous plant with an upright or spreading habit.
  
• Stems are almost translucent.
  
• Green succulent leaves are small.
  
• The branching gives it a fern-like appearance.
  
• Flowers are small and not showy.

High Risk Traits:

• Adapted to tropical climates
  
• Widely naturalized, including main Hawaiian Islands
  
• Garden and disturbance weed
  
• Nursery and horticultural weed
  
• Other Pilea species have become weedy
  
• Pollen a minor allergen
  
• Shade-tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds and vegetatively by stem fragments
  
• Capable of reaching maturity in one growing season
  
• Seeds dispersed intentionally by people, externally on birds and other animals, as a soil contaminant, and internally by deer (and possibly other animals)
  
• Able to resprout from roots and stems if not entirely removed

Low Risk Traits:

• Generally reported as a nuisance weed of yards and nurseries. Does not appear to be a problem in natural areas
  
• Unarmed (no spines, thorns, or burrs)
  
• Ornamental
  
• Herbicides provide effective control