Darkfield photomicrograph of a rose thorn showing general structure, stained section.
In plant morphology, thorns, spines, prickles, and in general spinose structures (as spinose teeth, spinose apical process) are all hard structures with sharp, stiff, ends, generally with the same function of mechanically deterring herbivory. In common language the terms are used more or less interchangeably, but in botanical terms, thorns are derived from shoots (so they can be branched or not, they can have leaves or not, and they arise from a bud), spines are derived from leaves (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 the epidermis (so they can be found anywhere on the plant, and don't have vascular bundles inside so they can be removed more easily and cleanly than thorns and spines. Leaf margins also may have teeth and if those teeth are sharp they are called spinose teeth, on a spinose leaf margin. On a leaf apex, if there is an apical process (generally an extension of the midvein), and if it is specially sharp, stiff, and spinelike, it can be called spinose or pungent apical process (again, some authors call them a kind of spine. When epidermis is covered with very long, stiff trichomes (more correctly called bristles in this case, for some authors a kind of prickle is called hispid vestiture, if is covered with stinging trichomes it can be called urent vestiture
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Photo credit: © Scenics & Science / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: darkfield, defence, general, microscope, photomicrograph, prick, rose, section., sharp, showing, spinose, stained, structure, thorn
