Editing Red (section)

=== Autumn leaves ===
{{More citations needed|section|date=July 2021}}
The red of autumn leaves is produced by pigments called [[anthocyanin]]s. They are not present in the leaf throughout the growing season, but are actively produced towards the end of summer.<ref name="tree1044">{{cite journal|last1=Archetti|first1=Marco|last2=Döring|first2=T. F.|last3=Hagen|first3=S. B.|last4=Hughes|first4=N. M.|last5=Leather|first5=S. R.|last6=Lee|first6=D. W.|last7=Lev-Yadun|first7=S.|last8=Manetas|first8=Y.|last9=Ougham|first9=H. J.|display-authors=3|year=2011|title=Unravelling the evolution of autumn colours: an interdisciplinary approach|journal=Trends in Ecology & Evolution|volume=24|issue=3|pages=166–73|doi=10.1016/j.tree.2008.10.006|pmid=19178979|last10=Schaberg|first10=Paul G.|last11=Thomas|first11=Howard}}</ref> They develop in late summer in the [[sap]] of the cells of the leaf, and this development is the result of complex interactions of many influences—both inside and outside the plant. Their formation depends on the breakdown of sugars in the presence of bright light as the level of [[phosphate]] in the leaf is reduced.<ref>{{Cite book|title=Plant pigments and their manipulation|date=2004|publisher=[[Wiley-Blackwell]]|isbn=978-1405117371|editor-last=Davies|editor-first=Kevin M.|location=Oxford|pages=6|oclc=56963804}}</ref>

During the summer growing season, phosphate is at a high level. It has a vital role in the breakdown of the [[sugar]]s manufactured by chlorophyll. But in the fall, phosphate, along with the other chemicals and nutrients, moves out of the leaf into the [[Plant stem|stem]] of the plant. When this happens, the sugar-breakdown process changes, leading to the production of anthocyanin pigments. The brighter the light during this period, the greater the production of anthocyanins and the more brilliant the resulting color display. When the days of autumn are bright and cool, and the nights are chilly but not freezing, the brightest colorations usually develop.

Anthocyanins temporarily color the edges of some of the very young [[leaf|leaves]] as they unfold from the [[bud]]s in early spring. They also give the familiar color to such common fruits as [[cranberry|cranberries]], [[Red Delicious|red apples]], [[blueberry|blueberries]], [[cherry|cherries]], [[raspberry|raspberries]], and [[plum]]s.

Anthocyanins are present in about 10% of tree species in temperate regions, although in certain areas—a [[autumn in New England|famous example being New England]]—up to 70% of tree species may produce the pigment.<ref name="tree1044" /> In autumn forests they appear vivid in the [[maple]]s, [[oak]]s, [[sourwood]], [[Liquidambar|sweetgums]], [[dogwood]]s, [[Tupelo (tree)|tupelo]]s, [[cherry]] trees and [[persimmon]]s. These same pigments often combine with the carotenoids' colors to create the deeper orange, fiery reds, and bronzes typical of many hardwood species. (See [[Autumn leaf color]]).