Leaves and sporangia developed in rare non-Fibonacci spirals in early leafy plants

Holly-Anne Turner, Matthew Humpage, Hans Kerp, Sandy Hetherington

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Lateral plant organs, including leaves and reproductive structures, are arranged on stems in distinct patterns, termed phyllotaxis. Most extant plants exhibit phyllotactic patterns that are mathematically described by the Fibonacci series. However, it remains unclear what lateral organ arrangements were present in early leafy plants. To investigate this, we quantified phyllotaxis in fossils of the Early Devonian lycopod Asteroxylon mackiei. We report diverse phyllotaxis in 20 leaves, including whorls and spirals. Spirals were all n:(n+1) non-Fibonacci types. We also show that leaves and reproductive structures occurred in the same phyllotactic series, indicating developmental similarities between the organs. Our findings shed light on the longstanding debate about leaf origins and demonstrate the antiquity of non-Fibonacci spirals in plants.
Original languageEnglish
Pages (from-to)1188-1192
Number of pages5
Issue number6650
Early online date15 Jun 2023
Publication statusPublished - 16 Jun 2023


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