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14 CRESSLEAF GROUNDSEL (Packera glabella) PLANT DESCRIPTION Cressleaf groundsel, or butterweed, is a broadleaf winter annual weed that can be seen in late spring to early summer as a 2–3 foot tall plant with terminal groups of yellow flowers. Seedlings germinate in fall and overwinter as a rosette before maturing in spring to early summer. Cressleaf groundsel can be easily identified by its yellow flowers and distinct leaf shape. LEAF: The leaves vary in shape and size but typically have multiple deep, rounded lobes with scalloped edges. The tip of the leaf is usually the broadest point. STEM: The stems are smooth, hollow, and slender with vertical ridges. Stems and leaves may have a purple tinge, especially when they are younger. As cressleaf groundsel matures, branching occurs in upward angles while flower buds develop. FLOWER: Flowers are daisy like with small yellow petals and yellow centers and are produced in groups mostly at the ends of branches. SEED: After flowering, seeds form in cottony tufts at the center of the flowers. REPRODUCTION: Seeds serve as the primary means of reproduction and can be dispersed long distances by wind. Mature cressleaf groundsel can produce thousands of seeds that can stay viable for up to three years. WHY IT IS NOXIOUS: Cressleaf groundsel is a member of a plant family that is known to possess a chemical compound that is toxic to the liver. Cressleaf groundsel poses a threat to livestock. SEASONAL IDENTIFICATION WHEN TO FIND: Cressleaf groundsel is most noticeable in large colonies from late spring or early summer when it is flowering. Spring seedlings and fall rosettes have a distinct leaf. SPRING IDENTIFICATION = MODERATE Overwintered seedlings/rosettes are found to be green after snow melts before most other Ohio plants turn green. The leaves have many lobes with toothed margins. Leaves and stems may have a purple tinge. SUMMER IDENTIFICATION = EASY As the plant matures, upward angled branches and flower buds develop. Yellow flowers emerge in clusters at the ends of branches and produce cottony, wind-dispersed seeds. After producing seed, cressleaf groundsel collapses and decomposes by midsummer. FALL IDENTIFICATION = MODERATE Seeds germinate in late summer or fall and emerge as a rosette or seedling. Leaves on rosettes or seedlings are often purple. WINTER IDENTIFICATION = DIFFICULT This plant persists as a rosette or seedling through winter. SIMILAR-LOOKING SPECIES COMMON GROUNDSEL (Senico vulgaris) has a very similar leaf, flower, and general appearance. The difference is that the leaves grow in the upper portions of the stem, unlike cressleaf groundsel. DANDELION (Taraxacum officinale) has similar seeds. When the flower goes to seed the seed head has a similar cottony tuft appearance. The lobes of the leaves are not as deep as those of cressleaf groundsel. YELLOW ROCKET (Barbarea vulgaris) yellow flowers grow in similar form at the top of the plant. The seeds form in bean pods. LOW HIGH ohio distribution roadside distribution growth seeds ability to dominate difficulty of control WHERE TO FIND: Cressleaf groundsel is common in Ohio and is considered an agriculture problem, not a maintenance concern for ODOT's right-of-way. This weed is typically found in wet soils or seasonally flooded agriculture fields and can grow in full sun or part shade of open woods. CONTROL METHODS: MECHANICAL: Mow for seed reduction in the spring. CHEMICAL: Make broadcast applications in fall with selective herbicide as rosettes and seedlings form. Broadcast pre-emergent herbicide to soils of infested areas in early summer before seeds germinate. CULTURAL: Plant tall fescue in fall and allow to grow tall in summer. Improve drainage. RECOMMENDATION SUMMARY: Cressleaf groundsel is a winter annual weed that germinates in fall, overwinters as a rosette, and produces flowers and seeds by late spring to early summer. Chemical control is the best option for this weed. Apply broadcast herbicide applications in fall as rosettes and seedlings are actively growing. Spring application to rosettes and seedlings can also be effective. If a large colony produces seed, prevent future germination by making pre- emergent herbicide applications to soil in late summer before seeds germinate. Make broadcast applications to large populations growing in turf or open fields with broadleaf selective herbicide. Mow to reduce flower and seed production. Plant tall fescue in fall and allow to grow tall the following summer to reduce seed germination and to provide competition for space and resources. Increase drainage in wet turf or fields to reduce ideal habitat for this weed. Failure to control cressleaf groundsel will allow prolific amounts of windblown seeds to spread into adjacent properties. This plant is toxic to livestock. winter annual RIVM LEVEL OF CONCERN

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