Parastichy

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

  1. ^ Webster's Revised Unabridged Dictionary. C. & G. Merriam Co. 1913.
  2. ^ Weise, Dmitriy (1998-10-29). "Principle of Minimax and Rise Phyllotaxis". Retrieved 2008-12-14.