Passion flower tendril. Coloured scanning electron micrograph of a spiral tendril from the common passion flower, Passiflora caerulea. Tendrils are modified leaves or stems used to grip nearby objects for support. In this way the passion flower acts like a parasite, using the structural strength of its neighbour to climb upwards and use some of the light that would have been used by the neighbouring plant. The tendril's shape is caused by the cells on one side growing slightly shorter than those on the other. P. caerulea originated in Brazil and has become widespread as a house and garden plant. Magnification: x13.5 at 6x7cm size.