≡ Menu

Weeds and Their Control: Green Alkanet (Pentaglottis sempervirens)

pentaglottis sempervirensAlso known as evergreen bugloss, this perennial weed is native to Western Europe where it grows in damp shaded areas especially those with calcareous soil. It is a member of the borage family, Borageaceae, that also includes heliotrope, Virginia bluebell, and forget me not. The generic name Pentaglottis comes from the Greek words penta meaning five and glottis meaning tongue, and refers to the five tongue-like scales on the corolla. The specific epithet sempervirens comes from the Latin words semper meaning always and virens meaning green. The common name alkanet comes from the Arabic word meaning henna and refers to the fact that the roots of the plant can be used to make a red dye.

Description: The plants grow up to three feet tall and have square, hairy stems and broadly oval, pointed leaves that are bristly and deeply veined. Loose clusters of hairy pink buds open in spring to small flowers with five sky blue petals and white centers. The root system is a thick, brittle, deep taproot that resprouts readily.

Control: Green alkanet reproduces by seed and root sprouts so is very difficult to eradicate. Immediate removal of seedlings by hand or hoe before the taproot develops and seeds are set is imperative. Older plants with taproots can be removed by deep digging but care must be taken to remove the entire root to avoid ressprouting. Repeat applications of a glyphosate-based weedkiller such as Roundup may be needed for severe infestations.