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Spines  [ Botany ]
Adjective: Spiny or Spinous

Dictionary of botanic terminology - index of names

  A spine is a stiff rigid structure with a sharp point from a highly modified leaf, scale, or stipule, usually contains vascular tissue and originate in the axil.  

Papyraceous spines of
Toumeya papyracantha
Eriosyce senilis subsp. coimasensis FR 473 new spines (neoporteria coimasensis)
New tender spring spines in early  growth resumption  of  Neoporteria coimasensis

When a "spine" originates from a stem modification and arise from the axillary or apical bud it is defined thorn. If it arises from the epidermis outside the branch it is called prickle, when it originates in leaves' margin or apex it is defined a marginal (or Apical) tooth. Nearly all cacti and some succulents have spines.

In Cactaceae, spines are a modified leaf lacking vascular tissue that arise and multiply from the areoles and detach easily. They are classified into central spines located centrally on the areole and radial spines around the margins, they can be stout and woody or fine and hair-like, woolly, bristly, needle-like, barbed, hooked or curved and variously coloured. Unlike other flowering plants that are principally identified by flower and fruit morphology, cacti are identified primarily by their spine clusters morphology.They protect the fat stem against some predators, even if inefficiently, but their most important function is to condense atmospheric moisture from dews, fog and rain (spines operate as a drip tip) so that they drip to the ground near the base of the plant for uptake by the superficial root system.
Often spines protect plants from the sun and from extreme temperatures, helping to preserve the plants from drying out.
They also allow to camouflage the plant (mimesis).


In succulents the spines often grow right from the stem tissue and are called thorns.


(Compare with thorns, prickles, bristle, glochid)








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