Which species exudes white, milky latex that can cause irritation?

• A. Leafy Spurge
• B. Spotted Knapweed
• C. Mediterranean Sage
• D. Diffuse Knapweed

Answer: (A)

White, milky latex is a telltale sign of leafy spurge, a Euphorbia weed. When the plant is broken or crushed, it oozes a thick white sap that can irritate the skin and eyes and mucous membranes. This irritant latex is not produced by the knapweeds or by Mediterranean sage, which have different sap characteristics and don’t exude a milky, latex-like fluid. Spotted knapweed and diffuse knapweed exchange a regular plant sap, but not the distinctive milky latex that causes irritation. So, the plant associated with that milky, irritant latex is leafy spurge.