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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.
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.
Although most echinoderm spines are blunt, those of the crown-of-thorns starfish are long and sharp and can cause a painful puncture wound as the epithelium covering them contains a toxin. [97] Because of their catch connective tissue, which can change rapidly from a flaccid to a rigid state, echinoderms are very difficult to dislodge from ...
By removing prickles from various species, including roses and eggplants, the authors found that a LOG gene was responsible for the prickles in about 20 types of plants studied.
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.
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.
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.
A dendrite (from Greek δένδρον déndron, "tree") or dendron is a branched cytoplasmic process that extends from a nerve cell that propagates the electrochemical stimulation received from other neural cells to the cell body, or soma, of the neuron from which the dendrites project.