![]() ![]() The fossils were obtained from the Rhynie chert, a roughly 400-million-year-old deposit of sedimentary rock in Aberdeenshire, Scotland, that contains exceptionally well-preserved fossils of some of the first land plants. In the new study, Sandy Hetherington, a paleobotanist at the University of Edinburgh, and colleagues studied fossils of the extinct Asteroxylon mackiei, a member of a group of plants called lycopods that also includes modern club mosses. Fibonacci spirals appear in the arrangement of leaves of some succulents (one shown at left), the bracts of a pinecone (middle) and in a seaside daisy (right). The patterns could also arise from the distribution of auxins, a type of plant growth hormone. Scientists aren’t sure why most modern plants adopt Fibonacci spiraling, but it might help maximize the amount of space between leaves or other plant parts ( SN: 7/21/07). If the numbers of clockwise and counterclockwise curves are both numbers found in the Fibonacci sequence, it’s known as Fibonacci spiraling. In plants with spiraling patterns of leaves, all the leaves can be described by a set of curved lines that spiral clockwise out from the center as well as by a set of curved lines that spiral counterclockwise. Examples of spirals in plants that involve Fibonacci numbers can be seen in the arrangement of the leaves of some succulents, the bracts of a pinecone and the seeds of a sunflower, among many other plants ( SN: 8/27/02). In the Fibonacci sequence, each number is the sum of the two previous ones: 1, 1, 2, 3, 5, 8, 13 and so on. The study “helps us to understand how 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.
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