Giant Sumpweed
Iva xanthifolia

Family: Asteraceae or Compositae

What it is like

An annual herb native to North America. It has been introduced to Western Asia and Central and Eastern Europe, where it is invasive.

Iva xanthifolia is a ANNUAL growing to 1 m (3ft 3in). The species is hermaphrodite (has both male and female organs). Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.

Height (m): 1

Where it is found

Not known

N. America. A casual in Britain.

Conservation Status: Iva xanthifolia - Status: Least Concern

Countries/locations it is found in

North America: Canada, USA. Europe: Austria, Croatia, Czech Republic, Germany, Hungary, Romania, Serbia, Slovakia, Slovenia, Switzerland. Oceania: New Zealand.

How it is used

Food

Rating: 0

Medicine

Rating: 1

An infusion or decoction of the plant has been drunk and used as a lotion in the treatment of coughs and influenza. A poultice of the plant has been used in the treatment of boils.

Other

Rating: 1

A possible substitute for some components of young rabbit forage, as it was palatable to them and had no toxic effects.

How it is grown

We have very little information on this species and do not know its cultivation needs. However, it is likely to succeed in most soils that are not too heavy or wet and will probably prefer a sunny position. The pollen of this species is one of the main causes of hay fever.

Propagating it: Seed -

Best place to grow: Cultivated Beds;

Habit: Annual

Hardiness: 0-0

Growth:

Soil: Light (sandy), medium, heavy (clay)

Shade: Semi-shade, no shade

Moisture: Moist

Things to keep in mind

If consumed by cows the milk may taste bitter. The leaves can cause dermatitis. The pollen of this plant can cause autumn hay fever.

North America native introduced to Western Asia and Central and Eastern Europe, where it is invasive. The pollen of Iva xanthiifolia can induce allergic diseases and it may become a serious source of allergens in Europe. Recorded infesting sugarbeet fields in Serbia. In Hungary, encroaching Iva xanthifolia threatens spring-sown row crops, such as sunflower, maize and sugarbeet. It can also cause considerable damage to sunflower plantations in Hungary.

Its other names

Local names

English: burweed marsh elder; burweed marshelder; burweed marshelder; carelessweed; false ragweed; giant marshelder; giant sumpweed; horseweed; marsh elder; marshelder; rag sumpweed. Austria: Rispenkrauts.

Synonyms

Cyclachaena xanthifolia. (Nutt.)Fresen.