Parastichy: Spiral formed by tracing the points of attachment of organs on an axis, such as leaves along a stem or scales along the central axis of a cone.*
The Euphorbia myrsinites growing in the Terrace Garden and Garden Hall Courtyard are a good example of parastichy. Notice how the leaves appear to spiral around the stem. Another example is the spiral pattern you may perceive when looking down at the top of a pine cone.
*Pell, S.K., Angell, B. (2016). A botanist’s vocabulary: 1300 terms explained and illustrated. Portland: Timber Press.