Trees need a certain number of warm days in their growing seasons to grow properly; otherwise, the cell walls of new growth ...

In order to grow properly, trees need an adequate period of warmth during their growing seasons; otherwise, the cell walls [… ...

A blue ring formed in 1902 in a tree in northern Norway. Image by Pawel Matulewski and Liliana Siekacz. Scientists studying pine trees and juniper shrubs in northern Scandinavia are revealing the ...

Blue growth rings in woody plant stems indicate years when cells failed to lignify properly due to summers that were too cold ...

Since trees and shrubs can live for hundreds of years, identifying these blue rings allows us to spot cold summers in the past. By looking at pine trees and juniper shrubs from northern Norway ...

The scientists collected core samples from 25 Scots pine trees and stem discs from 54 juniper shrubs, creating paper-thin ...

Learn more about these signs of summertime cold, perhaps tied to volcanic activity in 1877 and 1902.