Canadian Hemlock, Tsuga canadensis
Like many of our native trees, hemlocks are under attack by invading insects, in this instance, the wooly adelgid. Tree damage results from these insects feeding on (and eventually depleting) the trees’ sap. Since the insects are native to Japan, they have no natural predators to control their population size, thus invasion is eventually fatal if insects continue unrestrained proliferation. Trees stressed for other reasons, such as drought, are more vulnerable; healthier trees may ward off an infestation for several years. Current methods of prevention and treatment employ insecticides or release of imported beetles whose natural prey is the wooly adelgid.
This image of our native hemlock’s foliage was made by pressing a fresh branch onto a flat, inked plate. A moon was depicted by removing a circular area of ink on the background plate and adding wisps of ink to suggest clouds. Both plate and plant were covered with dampened print paper and the sandwich was squeezed between roller and hard bed of a hand-cranked press. Ink from the plate was thus forced directly onto the paper everywhere except where needles and stems kept ink from touching the paper, thus creating a negative image of the foliage, in reverse, as though seen through a mirror.
Multicolor images (not depicted) display ink from both foliage and plate. Although the same plant specimen can be used to make multiple images, exact replicas are not truly achievable because of such uncontrollable variables inherent in both specimen (if needles fell off between passes, for example) and in ink, both are altered to some extent during the printing process. Images made in this manner are therefore referred to as monotypes, or one-of-a-kind as opposed to a series of exact replicas.
Hemlock prints were also created by an alternative method: Using plant material to shield against light while exposing an emulsion-coated, “solar” plate. Using the plant to block the light source is similar to using it to block ink transfer to paper as described above, except that in this case the image on the plate is permanent. This “solar” image can be used to print exact replicas in a process to be described in a subsequent entry.
