Virginia Tech Weed Identification Guide

Cutleaf Eveningprimrose: Oenothera laciniata

Weed Description:  Usually a biennial or a winter annual, but may rarely occur as a summer annual.  Cutleaf eveningprimrose has leaves with deeply toothed margins and produces many showy yellow or red flowers.  This weed is primarily a weed of landscapes, nurseries, some agronomic crops, and occasionally turfgrass and lawns.  Cutleaf eveningprimrose occurs throughout the southern and eastern United States.
Seedlings:  Cotyledons are egg- or arrowhead-shaped and occur on petioles.  Leaves initially develop as a basal rosette.  Young leaves have margins that are untoothed (entire), but subsequent leaves have toothed margins.  Upper leaf surfaces of young leaves are usually hairy and lower leaf surfaces are without hairs.
Leaves:  Mature leaves may have hairs on the upper leaf surfaces but are without hairs below.  Leaves are lanceolate in outline, are relatively narrow, and have deeply toothed margins.  Leaves have a distinctive white midvein.
Stems:  Either prostrate or erect, hairy, and usually reddish in color.  When plants grow erect, stems may reach as much as 32 inches in height.

Roots:   A taproot.

Flowers:  Occur in the upper leaf axils and are without flower stems (sessile).  Flowers occur at the end of a long (1/2 to 1 1/4 inch) tube, which is actually the fused sepals.  Individual flowers are either red or yellow in color.

Fruit:   A capsule that is approximately 3/4 to 1 1/2 inches long and often curved.   Many seed are arranged in rows within the capsule.

Identifying Characteristics:   Erect or prostrate plants with lanceolate leaves that have toothed margins, red stems, and yellow or red flowers.  Cutleaf eveningprimrose is very similar in appearance to Common Eveningprimrose (Oenothera biennis), but common eveningprimrose has untoothed margins and usually grows much more erect than cutleaf eveningprimrose.