# Pinnation > Mediated Wiki article. Canonical URL: https://mediated.wiki/source/Pinnation > Markdown URL: https://mediated.wiki/source/Pinnation.md > Source: https://en.wikipedia.org/wiki/Pinnation > Source revision: 1339039386 > License: Creative Commons Attribution-ShareAlike 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) Type of spatial arrangement Look up ***[pinnation](https://en.wiktionary.org/wiki/Special:Search/pinnation)*** in Wiktionary, the free dictionary. A simple pinnate (unipinnate) frond of the fern *[Blechnum appendiculatum](/source/Blechnum_appendiculatum)*. **Pinnation** (also called **pennation**) is the arrangement of [feather](/source/Feather)-like or multi-divided features arising from both sides of a common [axis](/source/Anatomical_terms_of_location#Axes). Pinnation occurs in biological [morphology](/source/Morphology_(biology)), in [crystals](/source/Crystal),[1] such as some forms of [ice](/source/Ice_crystals) or [metal crystals](/source/Metallic_crystal),[2][3] and in patterns of [erosion](/source/Erosion) or [stream beds](/source/Stream_bed).[4] The term derives from the Latin word *pinna* meaning "feather", "[wing](/source/Wing)", or "[fin](/source/Fin)". A similar concept is "pectination", which is a [comb](/source/Comb)-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" are [cognates](/source/Cognate), and although they are sometimes used distinctly, there is no consistent difference in the meaning or usage of the two words.[5][6] ## Plants Further information: [Glossary of leaf morphology](/source/Glossary_of_leaf_morphology) [Botanically](/source/Botanically), pinnation is an arrangement of discrete structures (such as [leaflets](/source/Leaflet_(botany)), [veins](/source/Vein_(botany)), [lobes](/source/Lobes_(leaf)), [branches](/source/Branch), or [appendages](/source/Appendage)) arising at multiple points along a common axis. For example, once-divided leaf blades having leaflets arranged on both sides of a [rachis](/source/Rachis) are pinnately compound leaves. Many [palms](/source/Arecaceae) (notably the [feather palms](https://en.wikipedia.org/w/index.php?title=Feather_palm&action=edit&redlink=1)) and most [cycads](/source/Cycad) and [grevilleas](/source/Grevillea) have pinnately divided leaves. Most species of [ferns](/source/Fern) have pinnate or more highly divided [fronds](/source/Frond), 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's *Glossary of Botanical Terms*:[6] ### Depth of divisions - 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. - pinnately-lobed - pinnately-cleft - pinnately-parted - pinnately-divided - pinnatisect ### Number of divisions - 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 Bipinnate leaves of species of palm in the genus *[Caryota](/source/Caryota)* - 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 common [rachis](/source/Rachis). - bipinnate - geminate-pinnate - tripinnate The term *pinnula* (plural: *pinnulae*) is the Latin diminutive of *pinna* (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 In animals, pinnation occurs in various organisms and structures, including: - Some muscles can be unipinnate or [bipinnate muscles](/source/Bipinnate_muscles). - The fish *[Platax pinnatus](/source/Platax_pinnatus)* is known as the pinnate spadefish or pinnate batfish. ## Geomorphology 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.[9] ## References 1. **[^](#cite_ref-1)** Nicholas Eastaugh, Valentine Walsh, Tracey Chaplin, Ruth Siddall. *Pigment Compendium: A Dictionary of Historical Pigments*. Butterworth-Heinemann 2008. [ISBN](/source/ISBN_(identifier)) [978-0-7506-8980-9](https://en.wikipedia.org/wiki/Special:BookSources/978-0-7506-8980-9). 1. **[^](#cite_ref-2)** Charles Seymour Wright, Raymond Edward Priestley. *Glaciology*. Harrison and Sons, for the Committee of the Captain Scott Arctic Fund. 1922. 1. **[^](#cite_ref-3)** *Journal of the Electrochemical Society*, Volume 100, 1953, page 165: "The zinc is recovered electrolytically as 'flake' powder consisting of pinnate crystals." 1. **[^](#cite_ref-4)** Ravi P. Gupta. *Remote Sensing Geology*. Springer 2003. [ISBN](/source/ISBN_(identifier)) [978-3-540-43185-5](https://en.wikipedia.org/wiki/Special:BookSources/978-3-540-43185-5). 1. **[^](#cite_ref-5)** Collocott, T. C., ed. (1974). *Chambers Dictionary of science and technology*. Edinburgh: W. and R. Chambers. [ISBN](/source/ISBN_(identifier)) [0-550-13202-3](https://en.wikipedia.org/wiki/Special:BookSources/0-550-13202-3). 1. ^ [***a***](#cite_ref-BotGloss_6-0) [***b***](#cite_ref-BotGloss_6-1) Jackson, Benjamin, Daydon; *A Glossary of Botanic Terms with their Derivation and Accent*. Gerald Duckworth & Co. London, 4th ed 1928. 1. **[^](#cite_ref-RHS_7-0)** Chittenden, Fred J. Ed., *Royal Horticultural Society Dictionary of Gardening*. Oxford. 1951. 1. **[^](#cite_ref-8)** Shastri, Varun. *Dictionary of Botany*. Isha Books. 2005. [ISBN](/source/ISBN_(identifier)) [978-8182052253](https://en.wikipedia.org/wiki/Special:BookSources/978-8182052253). 1. **[^](#cite_ref-9)** Parvis, Merle (December 1949). ["DRAINAGE PATTERN SIGNIFICANCE IN AIRPHOTO IDENTIFICATION OF SOILS AND BEDROCKS*"](https://www.asprs.org/wp-content/uploads/pers/1950journal/jun/1950_jun_387-409.pdf) (PDF). *Joint Highway Research Project*. Retrieved 18 June 2025. --- Adapted from the Wikipedia article [Pinnation](https://en.wikipedia.org/wiki/Pinnation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Pinnation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.