Английская Википедия:Cyclachaena
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Cyclachaena xanthiifolia (syn. Iva xanthiifolia), known as giant sumpweed,Шаблон:R or rag sumpweed is a North American plant species in the sunflower family, Asteraceae. It is the only species in the genus Cyclachaena.Шаблон:R Giant sumpweed is believed to be native to the Great Plains but is now found across much of southern Canada and the contiguous United States, though rarely in the Southeast.Шаблон:R
It is an annual herb roughly Шаблон:Convert 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 base.Шаблон:R
In Britain and Ireland, it is known as marsh-elder.Шаблон:R It has been introduced and semi-naturalized in central and southern Britain, partly via seeds bought for bird food.Шаблон:R
Description
The leaf pattern of this herbaceous plant is opposite, sometimes becoming 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 Шаблон:Convert long or longer. Upper leaves are short-stalked, and the stalks are up to Шаблон:Convert long or longer.
The flowers are green to white in panicled spikes roughly Шаблон:Convert long. Some flowers are pistillate and fertile while others are perfect but sterile. The flowers bloom from August–October. The individual flower heads droop at the end of a Шаблон:Convert long or longer stalk. The whorl of bracts at the base of the flower head (involucre) is Шаблон:Convert 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 bloom 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 Шаблон:Convert 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 Шаблон:Convert long and whitish.Шаблон:R
The fruit is an egg-shaped achene, dark brown to nearly black, Шаблон:Convert long, with a tuft of hairs attached to one end.Шаблон:R
Habitat and ecology
Cyclachaena xanthiifolia grows in moist areas or previously disturbed sites. It can also be found in fields or along roadsides and streams.Шаблон:R
Effects
If consumed by cows, it 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.Шаблон:R
References
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