Which weed often has leaves with a bluish cast?

Which weed often has leaves with a bluish cast?

• A. Knotweed, Prostrate
• B. Puncturevine
• C. Nimblewill
• D. Nutsedge, Yellow

Answer: (A)

Leaves with a bluish cast are a clue that points to prostrate knotweed. That bluish tint comes from a waxy, glaucous coating on the small, oval to rounded leaves, which gives the plant a cool blue-green appearance, especially on new growth. It grows as a low, creeping mat in turf, so the bluish sheen is a helpful field mark when identifying it among common lawn weeds. Puncturevine, for contrast, has small, compound leaves that look quite different and lack that blue-glossy shine. Nimblewill is a creeping grass with blue-green blades, but its habit and leaf texture are more grasslike than the tiny broad leaves of knotweed. Yellow nutsedge has a yellow-green, linear leaf arrangement and a distinct sedge growth form, not a bluish cast on broad leaves. The blue-tinted leaves, therefore, best match prostrate knotweed.

Leaves with a bluish cast are a clue that points to prostrate knotweed. That bluish tint comes from a waxy, glaucous coating on the small, oval to rounded leaves, which gives the plant a cool blue-green appearance, especially on new growth. It grows as a low, creeping mat in turf, so the bluish sheen is a helpful field mark when identifying it among common lawn weeds.

Puncturevine, for contrast, has small, compound leaves that look quite different and lack that blue-glossy shine. Nimblewill is a creeping grass with blue-green blades, but its habit and leaf texture are more grasslike than the tiny broad leaves of knotweed. Yellow nutsedge has a yellow-green, linear leaf arrangement and a distinct sedge growth form, not a bluish cast on broad leaves. The blue-tinted leaves, therefore, best match prostrate knotweed.