Phyllotaxie et ramification du jeuneHuperzia selagoissu du développement de la bulbille

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

“…Despite this independent evolution, Fibonacci spirals are present in all three living clades of lycopods, just as they are in the major groups of euphyllophytes (5). However, in members of the Lycopodiales, non-Fibonacci spirals are present at a much higher frequency than Fibonacci spirals (4)(5)(6)(20)(21)(22)(23)(24). In some species, such as Lycopodium clavatum and Lycopodium annotinum, Fibonacci spirals occur at a frequency of <1% (5,20), whereas in others Fibonacci spirals occur at a higher frequency but are only associated with a small number of developmental stages (5,22,23).…”

“…However, in members of the Lycopodiales, non-Fibonacci spirals are present at a much higher frequency than Fibonacci spirals (4)(5)(6)(20)(21)(22)(23)(24). In some species, such as Lycopodium clavatum and Lycopodium annotinum, Fibonacci spirals occur at a frequency of <1% (5,20), whereas in others Fibonacci spirals occur at a higher frequency but are only associated with a small number of developmental stages (5,22,23). Why non-Fibonacci spirals predominate in the Lycopodiales compared with the other two clades of living lycopods is a subject of ongoing debate (6,20,23), and it is currently unknown whether non-Fibonacci spirals in the Lycopodiales represent a derived or ancestral characteristic (4,11).…”