spines (In Cactaceae family)
are the spines developing
around the margin of an areole,
projecting symmetrically about a central point and clearly
differentiated from centrals.
- Central spines (if present) are the larger of the two types
(stick out above the radials) and usually arise from the centre of the
areole, varying in number from one to several, with or without a
dominant(s) longer, stronger central spine, and secondary centrals of
different shape, size and colour.
Centrals are also frequently differentiated in upper (adaxial),
and lower (Abaxial)
depending on they orientation. They are often of a different colour
than the radials .
- Radial spines
are usually smaller and are located around the margin of the areole in
a single or superimposed
series of whorls .