A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no

petal Petals are modified Leaf, leaves that surround the reproductive parts of flowers. They are often advertising coloration, brightly colored or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''c ...

s, usually wind- pollinated ( anemophilous) but sometimes insect-pollinated (as in '' Salix''). They contain many, usually unisexual flowers, arranged closely along a central stem that is often drooping. They are found in many plant families, including Betulaceae,

Fagaceae The Fagaceae are a family of flowering plants that includes beeches, chestnuts and oaks, and comprises eight genera with about 927 species. Fagaceae in temperate regions are mostly deciduous, whereas in the tropics, many species occur as evergre ...

, Moraceae, and Salicaceae.

Occurrence

Catkin-bearing plants include many trees or

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...

s such as birch, willow, aspen,

hickory Hickory is a common name for trees composing the genus ''Carya'', which includes around 18 species. Five or six species are native to China, Indochina, and India (Assam), as many as twelve are native to the United States, four are found in Mexi ...

, sweet chestnut, and

sweetfern ''Comptonia peregrina'' is a species of flowering plant in the family Myricaceae. It is the only extant (living) species in the genus '' Comptonia'', although a number of extinct species are placed in the genus. ''Comptonia peregrina'' is native ...

(''Comptonia''). In many of these plants, only the male flowers form catkins, and the female flowers are single (

hazel The hazel (''Corylus'') is a genus of deciduous trees and large shrubs native to the temperate Northern Hemisphere. The genus is usually placed in the birch family Betulaceae,Germplasmgobills Information Network''Corylus''Rushforth, K. (1999). ...

, oak), a cone ( alder), or other types (

mulberry ''Morus'', a genus of flowering plants in the family Moraceae, consists of diverse species of deciduous trees commonly known as mulberries, growing wild and under cultivation in many temperate world regions. Generally, the genus has 64 identif ...

). In other plants (such as poplar), both male and female flowers are borne in catkins. In Britain, they can be seen in January or February, when many trees are bare for winter. They can even occur in December.

Evolution

For some time, catkins were believed to be a key synapomorphy among the proposed

Hamamelididae Hamamelididae is an obsolete botanical name at the rank of subclass. Because some hamamelidid members bear aments (''i.e.'', catkins), this subclass has been formerly known as ''Amentiferae''. Based on molecular phylogeny works, Hamamelididae app ...

, 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. 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. Such a convergent evolution raises questions about what the ancestral inflorescence characters might be and how catkins did evolve in these two lineages.

Etymology

The word ''catkin'' is a loanword from the Middle Dutch ''katteken'', meaning "

kitten A kitten is a juvenile cat. After being born, kittens display primary altriciality and are totally dependent on their mothers for survival. They normally do not open their eyes for seven to ten days. After about two weeks, kittens develop qu ...

" (compare also

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

''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. ''Ament'' is from the Latin ''amentum'', meaning "thong" or "strap".

Gallery

Fagales"> 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

('' Corylus avellana'') File:P3240141.JPG , Mature male catkins of

('' Corylus avellana'') File:Alder catkins - 3 (2222383499).jpg, Alder female catkins ('' Alnus'' sp.) Salicaceae"> 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.)

References

Plant morphology {{Botany-stub