Iva xanthiifolia Nutt.

Giant sumpweed, Cyclachaena xanthiifolia, is a member of the Asteraceae family. It is a nut-producing angiosperm (flowering plant) that flowers annually. Giant sumpweed is roughly 1–3 meters tall with stout, erect, branched stems. The stems are erect or ascending, finely ridged or grooved, and grayish-green. They are usually unbranched but sometimes have straight, upright branches. They are hairless near the base and are sparsely to moderately covered with fine curved or curled hairs above the bas.^[1]

Distribution[edit]

Drawing of Cyclachaena xanthiifolia

According to the USDA PLANTS dtabase Cyclachaena xanthiifolia is located in parts all around the United States and Canada. It is native all across the midwest from Michigan and Manitoba to Alberta and Mexico. It was later introduced to the Northeast, and the Pacific coast.^[2]

Habitat and ecology[edit]

Cyclachaena xanthiifolia grows in moist areas or previously disturbed sites.^[3] It can also be found in fields or along roadsides and streams.^[2]

Morphology[edit]

Individuals of this species are herbaceous. The leaf pattern is opposite with a possibility for alternate towards the top of the plant. The leaves are long stalked and double toothed with rough hairs on the top, and light green and fuzzy on the bottom. Lower leaves are long-stalked, the stalks up to 2¾″ long or longer stalks. Upper leaves are short-stalked, the stalks up to ⅜″ long or longer. The flowers are in green to white in panicled spikes roughly 10' long. Some flowers are pistilate and fertile while others are perfect but sterile. The flowers bloom from August–October. The individual flower heads droop at the end of a 3 ⁄16″ to ¼″ long or longer stalk. The whorl of bracts at the base of the flower head (involucre) is 1 ⁄16″ to ⅛″ long. The disk is composed of 8 to 20, usually no more than 10, male (staminate) florets in the center and usually 5 female (pistillate) florets around the margin. The flowers bllom from August–October. The staminate florets have stamens with the filaments fused into a tube and the anthers free but closely arranged in a ring. The corolla is about 1 ⁄16″ long and white to pale yellow. The pistillate florets have stamens with the filaments into a tube and the anthers free but closely arranged in a ring. The corolla is sometimes absent. When present it is about 1 ⁄64″ long and whitish.^[1][2][3]

Fruit[edit]

The fruit is an egg-shaped, dark brown to nearly black, 1 ⁄16″ to ⅛″ long achene with a tuft of hairs attached to one end.^[1]

Effects[edit]

Giant sumpweed, if consumed by cows, can make the milk that is produced taste bitter. The leaves can cause dermatitis in some individuals. The pollen of this plant can cause autumn hay fever in some individuals.^[2]

References[edit]