Radial spines

Radial spines [ Botany ]
Synonym: Lateral spines.

Dictionary of botanic terminology - index of names


	Radial 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.

Radial spines of
Coryphantha echinoidea

All spines of cacti are located on an areole usually in a cluster at the tips of the tubercles.
The spines themselves, with often neatly organized arrangements, are identified as two groups: The central spines and the radial spines, of varying quantities and shapes.

Spines may differ considerably in immature and adult specimens of the same species. The spines can be long or short, numerous or inexistent.

An areole may bear also bristles, glochids and wool.

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 .

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