Powdery mildew mould and ragweed pollen, SEM

Scanning electron micrograph (SEM) of Powdery mildew mould hyphae and spores and ragweed pollen (Ambrosia psilostachya). This pollen is an allergen. Moulds often produce allergic reactions and can cause serious agriculture diseases. Note the spores being produced on the ends of the fungal hyphae. Ragweed is a main cause of weed allergies. Ragweed pollen is notorious for causing allergic reactions in humans, specifically allergic rhinitis. Up to half of all cases of pollen-related allergic rhinitis in North America are caused by ragweeds. One of the main contributors to fall allergies is the ragweed plant. A single plant can produce one billion pollen grains per season. Ragweed grows abundantly throughout the South, North, and Midwest, and its lightweight pollen grains can travel up to 400 miles in the wind. Magnification: x400 when shortest axis printed at 25 millimetres.