Sunflower seed head. Seed head of a sunflower, Helianthus annuus, with the spiralling pattern on its surface representing a Fibonacci mathematical series. The plant produces composite flowers:- the small, true flowers are clustered into a compact, round head which resembles a single flower. The seeds produced by these flowers are used to make food for livestock and oil. A Fibonacci series is one in which each number is the sum of two previous numbers, for example: 0, 1, 2, 3, 5, 8, 13, 21 and so on. This series was discovered by Italian mathematician Leonardo Fibonacci (1170-1240) and many natural patterns can be described using it.