When a white pine has been infected with white pine blister rust (a fungus), cankers appear on the branches and sometimes the trunk of the tree. A large amount of sap-like ooze flows from the cankered areas, sometime drying and resembling a sugary-looking crust or film. These areas are, in fact, high in sugar content, and rodents frequently chew them. It’s likely that a red squirrel visited and sampled the infected white pine in the photograph, leaving a freshly-gnawed patch in the bark.
Bark, silhouettes and buds are the three keys to identifying trees in winter. My preference is buds, as they are so distinctly different from one species to the next. American basswood, or linden (Tilia americana), is a favorite. Its plump, oval, asymmetrical red buds, bearing only one or two bud scales are unmistakable.
Anyone familiar with the beautiful, smooth, gray bark of American beech is well aware that the forest landscape is changing, in part due to the disease that is affecting American beeches. Beech bark disease is caused by not one, but two, agents – an insect and a fungus. The bark of an American beech is initially attacked and altered by the soft-bodied scale insect, Cryptococcus fagisuga, after which it is invaded and killed by fungi, usually Nectria coccinea var. faginata or N. gallegina. This scale insect was accidentally introduced to Nova Scotia around 1890 and since then has spread far and wide, affecting large American beech trees (over 8 inches) the most. Pale yellow eggs are laid by the yellow female scale insects (there are no males – they reproduce through parthenogenesis) on the bark of beech trees in mid-summer and hatch in the late summer or fall. Larvae begin to feed on the bark until winter when they transform into a stage that has no legs and is covered with wool-like wax. The white wax secreted by beech scale insects is the first sign of the disease – heavy infestations of beech scale can cover tree trunks with white wax. Serious damage results only after the invasion of the bark by either one of the fungi mentioned, presumably through injuries made by scale feeding activity.
The fruits of the Hophornbeam tree (Ostrya virginiana), also known as Ironwood for its strong,hard wood, are drooping clusters of papery, bladder-like sacs each containing a nutlet. The “hop” portion of its name refers to the resemblance of its fruits to those of true hops that are used in the production of beer. Hornbeam refers to a related European tree whose wood was used to yoke oxen; therefore, its American counterpart wood was also used as a “beam” with which to yoke “horned” beasts of burden.
Black walnut (Juglans nigra) is one of the most sought-after native hardwoods. It has been heavily logged for its fine, straight-grained wood which has been used to make furniture, gunstocks and flooring. Because it is becoming increasingly rare, black walnut today is used primarily for veneer. The fruit of this tree is also highly prized, both for its meat as well as its shell, which is extremely difficult to crack, as anyone who has tried to do so by hand knows well. Because of this hardness, the shell has a number of commercial uses, including metal cleaning and polishing, oil well drilling, paints, explosives and cosmetic cleansers. If you would like to sample the sweet nut inside this shell, and are fortunate enough to know the location of a fruiting tree, the trick is to beat the squirrels to the nuts. After the first hard frost, collect the nuts. Eventually the green husks turn black and soften. After rinsing the nuts under water to remove the husks (beware that the husks are a natural dye and will stain your fingers), keep the nuts dry in a cool spot. The biggest challenge comes when you wish to extract the meat – commercial production involves running the nuts between two steel wheels. Barring that method, a hammer seems to do the trick.