|Scientific Name||Iva xanthiifolia Nutt.|
|Synonyms||Cyclachaena xanthiifolia (Nuttall) Fresenius|
|Common Names||English: False ragweed, burweed marsh-elder, careless-weed, German: Schlagkraut; French: Ive à feuilles de lampourde|
|Description||Tall robust annual, 0,6-1,8 m (1.97 - 5.9 ft) high, producing a taproot. I. xanthiifolia is native to North America.|
Relatively long furrows (10 µm, 0.00039 inch).
Long cotyledons and mostly opposite young leaves.
Moderately branched, grayish-green, smooth, up to 1-2 m (3.28 - 6.56 ft).
Leaves broad, mostly opposite, later alternate, light grayish-green, lower surface covered with small silky, soft hairs, with toothed margins, 5-20 cm (1.97 - 7.87 inch) long and 3-15 cm (1.18 - 5.9 inch) wide; ovate to broadly ovate, margins coarsely serrate to lobed, often double serrate.
Flower heads small, drooping, borne in panicles at top of stem and in axils of upper leaves. Flowers either male (inner staminate) or female (outer pistillate) but borne in the same head, without petals, white-greenish-yellow in color.
Gray to black, triangular, somewhat flattened with a ridged surface, about 3 mm (0.118 inch) long, produced in abundance.
Germination in spring.
Viability of Seeds
Long viability in the soil.
Abandoned fields, bottomlands, flood plains, stream banks.
Moist rich soils.
I. xanthifolia is a major weed problem in Texas pastures. The species is very prolific and can be difficult to manage if not controlled early. It can reduce forage, hay quality and yield. Similar to ragweed the pollen can cause hay fever. Native Americans harvested I. xanthifolia due to its oil content.
Useful non-chemical contribution to Integrated Weed Management
Frequent soil cultivation suppresses this weed on arable fields. In rangeland it is necessary to maintain intact pastures. Overgrazing provides good conditions for I. xanthifolia infestations.
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