Powdery mildew on a plant, coloured scanning electron micrograph (SEM). This is a fungus in the family Erysiphaceae, members of which are parasites of plants. When a spore lands on a plant it germinates and covers the surface in a network of thin thread-like hyphae (grey), called the mycelium. The mycelium absorbs nutrients from the plant's epithelial (surface) tissues, and produces erect conidiophores (the club-like structures here), which bear the fungal spores. The conidiophores cover the surface of the plant host, giving it the soft, powdery appearance responsible for the parasite's name. Magnification: x580 when printed 10cm wide.