There are also spines derived from roots, like the ones on the trunk of the 'Root Spine Palms' ( Cryosophila spp.). 'Root spines' on the trunk of a Cryosophila species. Pointing or spinose processes can broadly be divided by the presence of vascular tissue: thorns and spines are derived from shoots and leaves respectively, and have vascular bundles inside, whereas prickles (like rose prickles) do not have vascular bundles inside, so that they can be removed more easily and cleanly than thorns and spines. (2000) found that spines seem to have little effect on specialist pollinators, on which many plants rely in order to reproduce. For example, saguaro cactus spines shade the apical meristem in summer, and in members of the Opuntioideae, glochids insulate the apical meristem in winter.Īgrawal et al. In some cases, spines have been shown to shade or insulate the plants that grow them, thereby protecting them from extreme temperatures. Not all functions of spines or glochids are limited to defense from physical attacks by herbivores and other animals.

For this reason, they are classified as physical or mechanical defenses, as opposed to chemical defenses. The predominant function of thorns, spines, and prickles is deterring herbivory in a mechanical form. There can be found also spines or spinose structures derived from roots. When the leaf epidermis is covered with very long, stiff trichomes (more correctly called bristles in this case for some authors a kind of prickle ), it may be referred to as a hispid vestiture if the trichomes are stinging trichomes, it may be called a urent vestiture. On a leaf apex, if there is an apical process (generally an extension of the midvein), and if it is especially sharp, stiff, and spine-like, it may be referred to as spinose or as a pungent apical process (again, some authors call them a kind of spine ).

Leaf margins may also have teeth, and if those teeth are sharp, they are called spinose teeth on a spinose leaf margin (some authors consider them a kind of spine ). In common language the terms are used more or less interchangeably, but in botanical terms, thorns are derived shoots (so that they may or may not be branched, they may or may not have leaves, and they may or may not arise from a bud), spines are derived from leaves (either the entire leaf or some part of the leaf that has vascular bundles inside, like the petiole or a stipule), and prickles are derived from epidermis tissue (so that they can be found anywhere on the plant and do not have vascular bundles inside ).

3 Definitions and technical distinctions.

Plant with soft thorns