Definition of orthostichy in English:

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Pronunciation: /ɔːˈθɒstɪki/

noun (plural orthostichies)

(In phyllotaxis) a vertical row of leaves arranged one directly above another. Contrasted with parastichy.
Example sentences
  • Longitudinal section of shoot apex and an orthostichy of leaf primordia that are forming a rib.
  • Typically, they traverse the same number of internodes between the position at which they diverge from the minor axial bundles until they enter the branch base as the number of leaf orthostichies on the shoot.
  • Phyllotactic rows are easiest to identify in columnar cacti because vertically aligned leaf primordia merge together forming ribs (orthostichies).


Late 19th century: from ortho- 'upright, straight' + Greek stikhos 'row, rank'.

For editors and proofreaders

Line breaks: or|thos¦tichy

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