Definition of parastichy in US English:


nounPlural parastichies

  • (in phyllotaxis) an oblique row of leaves arranged in a secondary spiral.

    Contrasted with orthostichy
    • ‘Pistillate flowers, sterile male flowers, atypical bisexual flowers and staminate flowers are inserted on the same contact parastichies.’
    • ‘There was a negative correlation between phyllotaxy and leaf primordium diameter: species with greater numbers of orthostichies or parastichies had smaller leaf primordia.’
    • ‘However, in Jean's model it is not possible to determine the entropy of the phyllotactic system without knowing the number of visible opposed parastichies (m, n).’
    • ‘Curved lines show parastichies between stamens and last-formed tepals.’


Late 19th century: from para- ‘adjacent’ + Greek stikhos ‘row, rank’.