Parastichy

Parastichy, in phyllotaxy, is the spiral pattern of particular plant organs on some plants, such as areoles on cacti stems, florets in sunflower heads and scales in pine cones.

[1] These spirals involve the insertion of a single primordium.

[2]

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Spirals on a sunflower
Detail of Aeonium tabuliforme showing the multiple spiral arrangement (parastichy)