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. These spirals involve the insertion of a single primordium.
See also Embryology
Gerrit van Iterson
Phyllotaxis
References
External links Smith College, Spiral Lattices & Parastichy Interactive Parastichies Explorer