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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.
Spinous cells, or prickle cells, are keratin producing epidermal cells owing their prickly appearance to their numerous intracellular connections. They make up the stratum spinosum (prickly layer) of the epidermis and provide a continuous net-like layer of protection for underlying tissue.
The stratum spinosum (or spinous layer/prickle cell layer) [1] is a layer of the epidermis found between the stratum granulosum and stratum basale. [2] This layer is composed of polyhedral keratinocytes .
Pelvic fin of a Java barb, a ray-finned fish The short fin spines on a coelacanth, a lobe-finned fish A lionfish, with venomous spines The stinger on a stingray's tail. Spines are found in the fins of most bony fishes, particularly actinopterygians (ray-finned fishes), who have folding fan-like fin made of spreading bony spines called lepidotrichia or "rays" covered by thin stretches of skin.
The findings not only open the door for scientists looking to create prickle-free variants but also provide insight into the evolutionary history of an extremely diverse genus of plants, experts say.
Bursaria spinosa has a variable habit, and can grow anywhere from 1 to 12 m high. The dark grey bark is furrowed. The smooth branches are sometimes armed with thorns, and the leaves are arranged alternately along the stems or clustered around the nodes and have a pine-like fragrance when bruised.
Armed with prickle s, [13] e.g. the stem of a rose. acumen A long, tapering point, especially the apex of an acuminate leaf. acuminate Tapering gradually to a point, with concave sides approaching the point. [13] Contrast acute and mucronate. See also Leaf shape. acute 1. Sharply pointed, but not drawn out, with straight sides approaching the ...
Prickle on the other hand has a separate word, aculeus, but this seems to refer more to the curved shape than the origin. I think the "old" botanists would have scorned distinctions which relied on English words like "thorn"! Peter coxhead 21:36, 25 September 2013 (UTC)