Marshelder

Marshelder, Giant Sumpweed

Cyclachaena xanthifolia (Nutt.) Fresen.
(formerly Iva xanthifolia Nutt.)

Asteraceae (Sunflower Family)

▲ ▼ seedlings

▲ ▼ young plants

▲ ▼ stems and leaves, showing opposite leaf arrangement and stem and petiole hairs

▲ maturing plants

▲ ▼ leaf characteristics

▲ ▼ mature, flowering plants

▲ ▼ flowers/inflorescences

Cyclchaena xanthifolia (Nutt.) Fresen. (formerly Iva xanthifolia Nutt.) Giant Sumpweed, Marshelder: (Bayer Code: IVAXA; US Code IVXA)

U.S. native summer annual weed growing 3-8 feet tall with slightly-hairy, ridged stems; usually not much branching on stems until upper portions
Leaves are opposite, large, triangular to rounded-triangular with toothed margins and 3 main veins emerging from the long petiole (palmate veining)
Seedlings may have leaves that are more deeply 3-lobed in some locations
Flowers small, greenish in terminal panicles at tips of stems and from axils of upper stem leaves
Found in cultivated crops, non-crop areas, particularly in wetter soils
More common in northern Midwest and along Missouri & Mississippi rivers
Younger plants may appear similar to velvetleaf (Abutilon theophrasti) or annual sunflower (Helianthus annuus), but marshelder has small, green flowers, compared to the more showy flowers of velvetleaf and sunflower; also, velvetleaf has alternate, very soft fuzzy (velvety) leaves