Description:
Native to North America, Ragweed is a fern-like plant that is detrimental to the environment. Fast-growing, the weed often hampers agricultural, Ragweed grows between 1 to 2m in height. It features a flower spike up to 20cm long with yellow flowers when mature and small, black seeds.
As A Soil Indicator:
Very low Calcium, Very high Potassium, Very low Phosphorus, High Magnesium, High Sulfate, Low Copper, Little organic matter, Compacted soils
Life cycle: 
Annual. Seeds germinate in August to October after rain and grow quickly. Flowering starts in late summer and continues to May. Plants die in winter. Produces an average 3000 seeds per year with some producing up to 62,000. Seeds won’t germinate for some time after maturity. Exposure to light and alternating temperatures improves germination. Seeds become dormant with high temperatures and may survive for over 40 years.
Beneficial:
Used to stop bleeding or as a cure for dyspepsia. Good forage value for quail and cattle but unpalatable to horses. The seeds produce an oil with good drying qualities that is potentially useful for paints and varnishes
Detrimental:
Causes severe hay fever and dermatitis. Cattle eat young plants, but horses avoid it so that it often over-runs horse paddocks. It produces toxins that affect the growth of neighbouring plants. 
Toxicity:
Toxic. The unpleasant odour usually makes it distasteful to stock. It may cause a sore mouth in stock that graze it.Hay fever and skin irritations in people
.

What to read next?