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Prickles on a blackberry branch. In plant morphology, thorns, spines, and prickles, and in general spinose structures (sometimes called spinose teeth or spinose apical processes), are hard, rigid extensions or modifications of leaves, roots, stems, or buds with sharp, stiff ends, and generally serve the same function: physically defending plants against herbivory.
Paresthesia, also known as pins and needles, is an abnormal sensation of the skin (tingling, pricking, chilling, burning, numbness) with no apparent physical cause. [1] Paresthesia may be transient or chronic, and may have many possible underlying causes. [ 1 ]
Viburnum lesquereuxii leaf with insect damage; Dakota Sandstone (Cretaceous) of Ellsworth County, Kansas. Scale bar is 10 mm. Knowledge of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defense (such as spines) or herbivory-related damage; the observation of plant debris in fossilised animal feces; and the structure of herbivore mouthparts.
Prickles and thorns are an evolved defense against herbivores — animals that eat plants — and can also aid in growth, plant competition and water retention, according to the study.
The spines are the relatively large, radiating organs; the glochids are the fine prickles in the centres of the bunches. Glochids ( Opuntia microdasys monstrose ) Glochids or glochidia ( sg. : "glochidium") are hair-like spines or short prickles, generally barbed, found on the areoles of cacti in the sub-family Opuntioideae .
The hooks or teeth generally cause irritation, and some species commonly cause gross injury to animals, or expensive damage to clothing or to vehicle tires. [citation needed] Burs serve the plants that bear them in two main ways. Firstly, burs are spinescent and tend to repel some herbivores, much as other spines and prickles do. [3]
Dendritic spines serve as a storage site for synaptic strength and help transmit electrical signals to the neuron's cell body. Most spines have a bulbous head (the spine head), and a thin neck that connects the head of the spine to the shaft of the dendrite. The dendrites of a single neuron can contain hundreds to thousands of spines.
For example, the article says that spines are derived from leaves, but none of the four sources I listed at User:Peter coxhead/Work page#Spines vs. thorns restrict the term to leaf-derived structures. Also, the use of spinosus as an epithet is relevant; many plants with such names have what the article calls "thorns", e.g. Prunus spinosa.