Raised thorns on the stem of the wait-a-bit climber

Prickles on rose stems

Thorns of the Ocotillo

A spine is a rigid, pointed surface protuberance or needle-like structure on an animal, shell, or plant, presumably serving as a defense against attack by predators. For examples: the quills of a porcupine, the needles of a cactus, or the prickles of a shrub like the rose are all spines. Although spines generally serve as a passive defense mechanism, in some species they can be hollow and contain poisonous substances that cause lasting pain or even paralysis. Download high resolution version (500x667, 89 KB)Close up of Caesalpinia decapetala stem showing spines and lenticels. ... Download high resolution version (500x667, 89 KB)Close up of Caesalpinia decapetala stem showing spines and lenticels. ... Wikipedia does not have an article with this exact name. ... Wikipedia does not have an article with this exact name. ... Species About 100, see text A rose is a flowering shrub of the genus Rosa and the flower of this shrub. ... Binomial name Fouquieria splendens The ocotillo, Fouquieria splendens, is a curious desert plant of the southwestern United States and northern Mexico. ... Phyla Porifera (sponges) Ctenophora (comb jellies) Cnidaria (coral, jellyfish, anemones) Placozoa (trichoplax) Subregnum Bilateria (bilateral symmetry) Acoelomorpha (basal) Orthonectida (parasitic to flatworms, echinoderms, etc. ... Various seashells The hard, rigid outer covering of certain animals is called a shell. ... Divisions Land plants (embryophytes) Non-vascular plants (bryophytes) Marchantiophyta - liverworts Anthocerotophyta - hornworts Bryophyta - mosses Vascular plants (tracheophytes) Lycopodiophyta - clubmosses Equisetophyta - horsetails Pteridophyta - true ferns Psilotophyta - whisk ferns Ophioglossophyta - adderstongues Seed plants (spermatophytes) †Pteridospermatophyta - seed ferns Pinophyta - conifers Cycadophyta - cycads Ginkgophyta - ginkgo Gnetophyta - gnetae Magnoliophyta - flowering plants Adiantum pedatum (a fern... Genera Family Erethizontidae   Coendou   Sphiggurus   Erethizon   Echinoprocta   Chaetomys Family Hystricidae   Atherurus   Hystrix   Thecurus   Trichys Porcupines are rodents best known for their coat of sharp spines, or quills, that defend them from predators. ... Genera See Taxonomy of the Cactaceae A cactus (information regarding the plural of catcus below) is a type of (usually) succulent plant belonging to the dicotyledonous flowering plant family, Cactaceae. ... A broom shrub in flower A shrub or bush is a horticultural rather than strictly botanical category of woody plant, distinguished from a tree by its multiple stems and lower height, usually less than 6 m tall. ... Species About 100, see text A rose is a flowering shrub of the genus Rosa and the flower of this shrub. ... The skull and crossbones symbol traditionally used to label a poisonous substance. ... Pain is an unpleasant sensation which may be associated with actual or potential tissue damage and which may have physical and emotional components. ... Paralysis is the complete loss of muscle function for one or more muscle groups. ...

Plant spines and thorns

Botanists use several terms somewhat loosely when referring to spine- or needle-like structures on plants; however, the following differences are typically distinguished:

• prickle – a sharp outgrowth from the epidermis, also called an emergence and usually involving some subdermal tissue as well; see also hair.
• spine – a modified stipule or sharp branchlet found in a leaf axil or on the margin of a leaf.
• thorn – Sharp outgrowth from a stem other than at a node; a modified stem.

Thorns and prickles, most notably those on roses, are common literary symbols for the hidden dangers or woes of something beautiful or pleasant, as in "Every rose has its thorn." Roses lack true thorns since their prickles emerge from the epidermis rather that the pericycle. Growth from the pericycle would make it a modifided stem and therefore a thorn. Some roses have been bred not to have prickles. Other examples of plants with these characteristics include: the thistle, some berry plants, and a number of plants in the weed family. Epidermis could refer to: In plants, the outermost layer of cells covering the leaves and young parts of a plant is the epidermis. ... Interior structure of a common cannabis trichome. ... The lanceolate-linear, paired stipules of Hibiscus kokio In botany, stipule refers to outgrowths borne on either side of the base of a leafstalk (or petiole). ... In botany, a leaf is an above-ground plant organ specialized for photosynthesis. ... A stem is the above ground axis of a vascular plant. ... Species See text Thistles are perennial flowering plants of the genus Cirsium. ... Several types of berries from the market, but none of these are true berries. ... A weed is an unwanted plant. ...

See also

• Seta

SETA (Seksuaalinen Tasavertaisuus RY, Sexual Equality), the main gay and lesbian rights organisation in Finland. ...

References

• Esau, K. 1965. Plant Anatomy, 2nd Edition. John Wiley & Sons. 767 pp.
• Llamas, K. A. 2003. Tropical Flowering Plants. Timber Press, Portland. 423 pp.