False-colour scanning electron micrograph (SEM) of the fungus Alternaria alternata, a causative agent of respiratory allergies. Here, fungal threads of the vegetative mycelium are seen, each thread is called a hypha, with a spore-producing fruiting body at centre right. Large amounts of spores are produced by this fungus, leading to its allergic properties. Alternaria alternata is a cause of both allergic rhinitis (hay fever) in which infla- mmation of the mucous membrane of the nose occurs; and of allergic asthma. Asthma is the more serious condition, affecting the lungs. Repeated inhaling of fungal spores may cause hypersensitivity reac- tions. Magnification: x685 at 6x7cm size.