catkin
{{Short description|Cylindrical flower cluster}}
File:Salix caprea Male.jpg (Salix sp.)]]
A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in Salix). It contains many, usually unisexual flowers, arranged closely along a central stem that is often drooping. Catkins are found in many plant families, including Betulaceae, Fagaceae, Moraceae, and Salicaceae.
Occurrence
Catkin-bearing plants include many trees or shrubs such as birch, willow, aspen, hickory, sweet chestnut, and sweetfern (Comptonia).{{citation needed|date=February 2023}}
In many of these plants, only the male flowers form catkins, and the female flowers are single (hazel, oak), a cone (alder), or other types (mulberry). Corylus jacquemontii has male catkins and also female spikes.{{cite web |title=Jacquemont's Hazel |url=http://www.flowersofindia.net/catalog/slides/Jacquemont's%20Hazel.html |publisher=flowersofindia.net |access-date=7 July 2020}}
In other plants (such as poplar), both male and female flowers are borne in catkins. Populus alba has male catkins which are grey and the female catkins are greyish-green.Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=2198 Populus alba] {{webarchive|url=https://web.archive.org/web/20100827110425/http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=2198 |date=2010-08-27 }}
While the blooming months for catkins may vary due to factors such as climate change and latitude, the following are some general timeframes: Hazel catkins bloom from January to March, alder catkins from February to March, silver birch catkins from March to May, oak catkins from April to May, and white willow catkins from April to May.{{Cite web |last=Trust |first=Woodland |title=Which trees have catkins and how to ID them |url=https://www.woodlandtrust.org.uk/blog/2018/12/which-trees-have-catkins-and-how-to-tell-them-apart/ |access-date=2023-02-23 |website=Woodland Trust |language=en-GB}}
In Britain, catkins can be seen in January or February, when many trees are bare for winter. They can even occur in December.{{Cite news |url=http://www.bbc.com/earth/story/20150127-an-early-hazel-catkin-year |url-status=dead |archive-url=https://web.archive.org/web/20190106072714/http://www.bbc.com/earth/story/20150127-an-early-hazel-catkin-year |author=Rose Sanderson |title=An early catkin year |date=2015-01-30 |archive-date=2019-01-06 |access-date=2022-11-25 |publisher=BBC Earth}}
Evolution
For some time, catkins were believed to be a key synapomorphy among the proposed Hamamelididae, also known as Amentiferae (i.e., literally plants bearing aments). Based on molecular phylogeny work, it is now believed that Hamamelididae is a polyphyletic group.Savolainen, V., M. W. Chase, S. B. Hoot, C. M. Morton, D. E. Soltis, C. Bayer, M. F. Fay, A. Y. De Bruijn, S. Sullivan, and Y.-L. Qiu. 2000. Phylogenetics of flowering plants based on combined analysis of plastid atpB and rbcL gene sequences. Systematic Biology 49:306-362.Soltis, D. E. et alii. (28 authors). 2011. "Angiosperm phylogeny: 17 genes, 640 taxa". American Journal of Botany 98(4):704-730. {{doi|10.3732/ajb.1000404}} This suggests that the catkin flower arrangement has arisen at least twice independently by convergent evolution, in Fagales and in Salicaceae.Cronk Q. C. B., Needham I., and Rudall P. J. 2015. Evolution of catkins: inflorescence morphology of selected Salicaceae in an evolutionary and developmental context. Frontiers in Plant Science. 2015; 6: 1030. {{doi|10.3389/fpls.2015.01030}} Such a convergent evolution raises questions about what the ancestral inflorescence characters might be and how catkins did evolve in these two lineages.
Etymology
File:Pussy Willows by Margaret Ely Webb.jpg catkins from a children's book]]
The word catkin is a loanword from the Middle Dutch katteken, meaning "kitten" (compare also German Kätzchen). This name is due either to the resemblance of the lengthy sorts of catkins to a kitten's tail, or to the fine fur found on some catkins.{{citation|title=Catkin|journal=Oxford English Dictionary|edition=Second|date=1989|access-date=30 November 2009|url=http://dictionary.oed.com/cgi/entry/50034696}}{{Cite web|url=http://www.etymologiebank.nl/trefwoord/katje1|title=Zoekresultaten|website=www.etymologiebank.nl}} Ament is from the Latin amentum, meaning "thong" or "strap".{{citation|title=Ament|journal=Oxford English Dictionary|edition=Second|date=1989|access-date=30 November 2009|url=http://dictionary.oed.com/cgi/entry/50007124}}
Gallery
File:Ostrya carpinifolia in Italy male catkins.jpg |Male catkins of hop-hornbeam (Ostrya carpinifolia)
File:Catkins Corylus avellana-Mont Bart-5124~2015 12 26.JPG |Young male catkins of hazel (Corylus avellana)
File:P3240141.JPG |Mature male catkins of hazel (Corylus avellana)
File:Young-catkin.jpg |Young male catkin of a willow (Salix sp.)
File:Willow catkin 2 aka.jpg |Three male catkins on a willow (Salix sp.)
File:Salix female catkin.jpg |Female flowering catkin on a willow (Salix sp.)