This specimen, with two separate trunks bridged midway up, is an example of self-grafting. When two tree trunks or branches grow in close proximity and touch each other, and if the bark then becomes abraded, the trunks can become physiologically connected (or grafted).
Grafting techniques, so critical to modern horticulture, may have first emerged as early humans tried to mimic the natural grafting they saw in the wild — such as demonstrated by this Hemlock.
This amazing species, which can be dominant in riparian habitats, plays an important role in the area’s water cycle by regulating stream flow. Where Hemlock loss is great (due to the invasive woolly adelgid), summer stream flow can be lowered and stream temperature increased, with wide-ranging impacts on the surrounding ecosystem.
