{{Short description|In botany, the ultimate unit of a compound leaf}} [[File:Potleaf.jpg|thumb|Palmately compound leaf of hemp]] A '''leaflet''' (occasionally called '''foliole''') in botany is a leaf-like part of a compound leaf.<ref name="WaltersKeil1996">{{cite book|last1=Walters |first1=Dirk R.|last2=Keil |first2=David J. |year=1996 |title=Vascular Plant Taxonomy |url=https://archive.org/details/vascularplanttax00walt/page/33 |url-access=registration |edition=4th |location=Dubuque, Iowa, USA |publisher=Kendall Hunt Publishing Company |page=33 |isbn=978-0-7872-2108-9}}</ref> Though it resembles an entire leaf, a leaflet is not borne on a main plant stem or branch, as a leaf is, but rather on a petiole or a branch of the leaf.<ref>{{cite web |url=https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/30%3A_Plant_Form_and_Physiology/30.4%3A_Leaves/30.4B%3A__Types_of_Leaf_Forms |title=Types of Leaf Forms |date=16 July 2018 |website=Biology LibreTexts |access-date=30 March 2021}}</ref>
Compound leaves are common in many plant families and they differ widely in morphology.<ref>{{Cite journal|last1=Koch|first1=Garance|last2=Rolland|first2=Gaëlle|last3=Dauzat|first3=Myriam|last4=Bédiée|first4=Alexis|last5=Baldazzi|first5=Valentina|last6=Bertin|first6=Nadia|last7=Guédon|first7=Yann|last8=Granier|first8=Christine|year=2018|title=Are compound leaves more complex than simple ones? A multi-scale analysis|journal=Annals of Botany|publication-date=December 2018|volume=122|issue=7|pages=1173–1185|doi=10.1093/aob/mcy116|issn=0305-7364|pmc=6324747|pmid=29982438}}</ref> The two main classes of compound leaf morphology are palmate and pinnate. For example, a ''hemp'' plant has palmate compound leaves,<ref>{{Cite journal |last=Balant |first=Manica |last2=Garnatje |first2=Teresa |last3=Vitales |first3=Daniel |last4=Hidalgo |first4=Oriane |last5=Chitwood |first5=Daniel H. |date=2024 |title=Intra-leaf modeling of Cannabis leaflet shape produces leaf models that predict genetic and developmental identities |url=https://onlinelibrary.wiley.com/doi/abs/10.1111/nph.19817 |journal=New Phytologist |language=en |volume=243 |issue=2 |pages=781–796 |doi=10.1111/nph.19817 |issn=1469-8137|hdl=10261/371797 |hdl-access=free }}</ref> whereas some species of ''Acacia'' have pinnate leaves.<ref>{{Cite web |title=Robinia hispida {{!}} rose acacia Shrubs/RHS |url=http://www.rhs.org.uk/plants/91229/robinia-hispida/details |access-date=2025-11-23 |website=www.rhs.org.uk |language=en-gb}}</ref>
The ultimate division (or leaflet) of a compound leaf, or a pinnate subdivision of a multipinnate leaf is called a '''pinnule''' or '''pinnula'''.<ref>{{Cite web |date=2025-11-17 |title=PINNULATE definition and meaning {{!}} Collins English Dictionary |url=https://www.collinsdictionary.com/dictionary/english/pinnulate |access-date=2025-11-23 |website=www.collinsdictionary.com |language=en}}</ref>
<gallery> Image:Ветвь акации.jpg|Pinnate leaf of a legume with 10 leaflets Image:Mimosa Pudica.gif|''Mimosa pudica'' folding leaflets inward. </gallery>The different shapes of leaflets can be described as elliptical, oval, lanceolate or other shapes. Leaflets can be divided in different ways; for example, unipinnate, which is a simple pinnate with leaflets, where no more divisions occur (e.g. Cassia), bipinnate, which has secondary leaflets, with each leaflet dividing into another set of leaflets (e.g. Acacia) and tripinnate, where further division occurs after the secondary leaflets (e.g. Moringa).<ref name=":0" />
It can be difficult to tell the difference between a leaf and a leaflet, because leaflets look like a small leaf, but are actually a segment of a compound leaf and are also not attached to the stem.<ref>{{Cite web |date=2014-02-06 |title=Difference between Leaf and Leaflet |url=https://www.differencebetween.info/difference-between-leaf-and-leaflet |access-date=2025-11-23 |website=www.differencebetween.info}}</ref> Leaflets do not ever have axillary buds.<ref>{{Cite news |title=Plant Morphology: Leaf Type |url=https://www.amnh.org/learn-teach/curriculum-collections/biodiversity-counts/plant-identification/plant-morphology/leaf-type |archive-url=http://web.archive.org/web/20250618041149/https://www.amnh.org/learn-teach/curriculum-collections/biodiversity-counts/plant-identification/plant-morphology/leaf-type |archive-date=2025-06-18 |access-date=2025-11-23 |work=American Museum of Natural History |language=en-US}}</ref>
==Etymology== '''Leaflet''' includes the words leaf and let. Leaf originates from an Old English word that reflects a plant’s foliage. The suffix ''-“let”,'' comes from a Middle English and Old French word, meaning lesser or smaller of something. Leaflet therefore means a "''petite version of a typical leaf structure”''.<ref name=":0">{{Cite web |title=Leaflets - Definition and Examples - Biology Online Dictionary |url=https://www.biologyonline.com/dictionary/leaflets |access-date=2025-11-23 |website=Biology Articles, Tutorials & Dictionary Online |language=en-US}}</ref>
== See also == {{Wiktionary}} * Compound leaf {{clear}}
== References == {{Reflist|30em}}
Category:Leaf morphology