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]

Spirals on a sunflower

Detail of Aeonium tabuliforme showing the multiple spiral arrangement (parastichy)

See also

• Embryology
• Fibonacci number § Nature
• Gerrit van Iterson
• Golden ratio § Nature
• Phyllotaxis