Crocus flowers are among the first flowers of Spring, often emerging long before the danger of snow and freezing weather has passed. Once the bud is mature, the flower will open fairly on warm sunny days. The growth of cells in flower petals of crocus and tulip flowers is responsive to temperature. When warm, cells on the inside surface of the petals grow faster than cells on the outside surface. When cold, like at night, cells on the inner surface slow their growth and cells on the outer surface grow relatively faster causing the flower to close. The yellow crocus flower in this movie was picked on a cold night and brought indoors where it warmed and the flower opened in less than an hour (each frame was captured two minutes apart).

Want to see a white crocus open?