A 407-million-year-old plant’s leaves skipped the usual Fibonacci spirals

An unusual arrangement of leaves in a 407-million-year-old fossilized plant is complicating scientists’ understanding of plant evolution.

Most land plants living today have spiral patterns involving the famous Fibonacci sequence of numbers. Because the spirals are so common, scientists have thought that the patterns must have evolved in some of the earliest land plants. But the leaves of the ancient plant, a member of one of the first plant groups known to have developed leaves, were arranged in spirals that can’t be described by Fibonacci numbers, researchers report in the June 16 Science.

The study “helps us to understand how [the] diversity of plants has been generated,” says botanist Barbara Ambrose, the director of laboratory research at the New York Botanical Garden in New York City, who was not involved in the research.

In the Fibonacci sequence, each number is the sum of the two previous ones: 1, 1, 2, 3, 5, 8, 13 and so on. Examples of spirals in plants that involve Fibonacci numbers can be seen in the arrangement of the leaves of some…