Pinnation
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Pinnation(also calledpennation) is the arrangement offeather-like or multi-divided features arising from both sides of a commonaxis.Pinnation occurs in biologicalmorphology,incrystals,[1]such as some forms oficeormetal crystals,[2][3]and in patterns oferosionorstream beds.[4]
The term derives from the Latin wordpinnameaning "feather", "wing",or"fin".A similar concept is" pectination ", which is acomb-like arrangement of parts (arising from one side of an axis only). Pinnation is commonly referred to in contrast to "palmation", in which the parts or structures radiate out from a common point. The terms "pinnation" and "pennation" arecognate,and although they are sometimes used distinctly, there is no consistent difference in the meaning or usage of the two words.[5][6]
Plants
[edit]Botanically,pinnation is an arrangement of discrete structures (such asleaflets,veins,lobes,branches,orappendages) arising at multiple points along a common axis. For example, once-divided leaf blades having leaflets arranged on both sides of arachisare pinnately compound leaves. Manypalms(notably thefeather palms) and mostcycadsandgrevilleashave pinnately divided leaves. Most species offernshave pinnate or more highly dividedfronds,and in ferns, the leaflets or segments are typically referred to as "pinnae" (singular "pinna" ). Plants with pinnate leaves are sometimes colloquially called "feather-leaved". Most of the following definitions are from Jackson'sGlossary of Botanical Terms:[6]
Depth of divisions
[edit]- pinnatifid and pinnatipartite: leaves with pinnate lobes that are not discrete, remaining sufficiently connected to each other that they are not separate leaflets.
- pinnatisect: cut all the way to the midrib or other axis, but with the bases of the pinnae not contracted to form discrete leaflets.
- pinnate-pinnatifid: pinnate, with the pinnae being pinnatifid.
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pinnately-lobed
-
pinnately-cleft
-
pinnately-parted
-
pinnately-divided
-
pinnatisect
Number of divisions
[edit]- paripinnate: pinnately compound leaves in which leaflets are borne in pairs along the rachis without a single terminal leaflet; also called "even-pinnate".
- imparipinnate: pinnately compound leaves in which there is a lone terminal leaflet rather than a terminal pair of leaflets; also called "odd-pinnate".
-
even pinnate
-
odd pinnate
-
alternipinnate
Iteration of divisions
[edit]- bipinnate: pinnately compound leaves in which the leaflets are themselves pinnately compound; also called "twice-pinnate".
- tripinnate: pinnately compound leaves in which the leaflets are themselves bipinnate; also called "thrice-pinnate".
- tetrapinnate: pinnately compound leaves in which the leaflets are themselves tripinnate.
- unipinnate: solitary compound leaf with a row of leaflets arranged along each side of a commonrachis.
-
bipinnate
-
geminate-pinnate
-
tripinnate
The termpinnula(plural:pinnulae) is the Latin diminutive ofpinna(plural:pinnae); either as such or in the Anglicised form:pinnule,it is differently defined by various authorities. Some apply it to the leaflets of a pinna, especially the leaflets of bipinnate or tripinnate leaves.[7]Others also or alternatively apply it to second or third order divisions of a bipinnate or tripinnate leaf.[8] It is the ultimate free division (or leaflet) of a compound leaf, or a pinnate subdivision of a multipinnate leaf.
Animals
[edit]In animals, pinnation occurs in various organisms and structures, including:
- Some muscles can be unipinnate orbipinnate muscles
- The fishPlatax pinnatusis known as the pinnate spadefish or pinnate batfish.
Geomorphology
[edit]Pinnation occurs in certain waterway systems in which all major tributary streams enter the main channels by flowing in one direction at an oblique angle.[citation needed]
References
[edit]- ^Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall.Pigment Compendium: A Dictionary of Historical Pigments.Butterworth-Heinemann 2008.ISBN978-0-7506-8980-9.
- ^Charles Seymour Wright, Raymond Edward Priestley.Glaciology.Harrison and Sons, for the Committee of the Captain Scott Arctic Fund. 1922.
- ^Journal of the Electrochemical Society,Volume 100, 1953, page 165: "The zinc is recovered electrolytically as 'flake' powder consisting of pinnate crystals."
- ^Ravi P. Gupta.Remote Sensing Geology.Springer 2003.ISBN978-3-540-43185-5.
- ^Collocott, T. C., ed. (1974).Chambers Dictionary of science and technology.Edinburgh: W. and R. Chambers.ISBN0-550-13202-3.
- ^abJackson, Benjamin, Daydon;A Glossary of Botanic Terms with their Derivation and Accent.Gerald Duckworth & Co. London, 4th ed 1928.
- ^Chittenden, Fred J. Ed.,Royal Horticultural Society Dictionary of Gardening.Oxford. 1951.
- ^Shastri, Varun.Dictionary of Botany.Isha Books. 2005.ISBN978-8182052253.