On Sunday, Dec 18, Mother Nature did not cooperate with my plans to lead a tour of the conifer section of Longenecker Horticultural Gardens. The air temperature hovered just below zero, and the wind chill carried danger of frostbite to uncovered skin within 30 minutes. Not the time to hike to the top of a windy hill!
Despite those harsh circumstances, one hardy soul showed up and we spent some enjoyable time in a windowed alcove of the Visitor Center lobby, where we had a fine view of white pines, red cedars, and yews—three of the species I would have pointed out anyway. Also noticeable against the snow and the evergreen backdrop were scattered white birches, and the garnet-red fruits of smooth sumac. The latter—which always remind me of flags or pennants—are an excellent source of Vitamin C for winter birds. People can make a hot or cold beverage from them, too.
The conifer collection in Longenecker Horticultural Gardens was planted on the south-facing slope of a drumlin to give these trees the slightly more acid, better-drained soil they prefer. There are defined areas for pines, junipers, spruces, firs, and yews, although exceptions can be found. A look at the garden map provided in our newsprint guide, or online, will show the general groupings.
Each type and species of conifer has its own characteristic color, needle length, growth habit, and natural shape. However, horticulturists over the years have selected and propagated for a wide variety of characteristics which people may desire for landscaping purposes. For instance, there are “weeping” or pendulous cultivars of pines, spruces, junipers, and even larches; and the “witches’ broom” phenomenon (an area of abnormally dense growth) can sometimes be capitalized on to produce dwarf-sized, very full trees. Bluish or yellow colors have been developed for several different types of conifer as well. (Personally, I prefer my evergreens to be . . . well . . . green.)
My guest asked about the Fraser fir (Abies fraseri). I knew it was not one of our native Wisconsin conifers. A quick look in a field guide told us it’s closely related to the balsam fir (A. balsamea), which is native here. The Fraser grows in the Appalachian Mountain region. Fir trees feature resin-filled “blisters” on their bark; the resin from balsam fir, in particular, has commercial value for mounting laboratory specimens and was used by native people to heal burns. Both the Fraser and balsam firs are popular as Christmas trees.
We examined small branches of white pine, white cedar, red “cedar” (actually a juniper), and yew that I had brought in. A very distinctive characteristic of pines is that the needles occur in bundles which are wrapped at the base by a bit of crispy, tan-colored tissue called a fascicle.
Other conifers—except for the tamaracks and larches, which are bare in the winter anyway, so you will not confuse them with the evergreens—bear their needles one by one along their twigs, not clustered. Scaly needles indicate the cedars and junipers.
Of course there are distinctive differences in the cones each type of tree bears as well. I’m partial to the closed (serotinous) cone of the jack pine. Tightly sealed, it only opens in the presence of intense heat. Thus jack pine seeds are released when a fire roars through the stand—the very flame which kills the adult tree delivering the means by which it can regenerate.
My favorite jack pine in the Arboretum is “Uncle Fogy.” I am not making that name up. Near the upper bench at the top of the hill, there is a specimen of Pinus banksiana which is uniquely contorted/weeping in shape. The cultivar name truly is “Uncle Fogy,” although I cannot tell you why. In our Wisconsin sand counties, jack pines grow upright, up to 70 feet tall.
I should mention yews before ending these notes. Most of them qualify as shrubs, not trees. At one time the Japanese yew (Taxus cuspidata) was a very popular planting around house foundations or as a hedge. It’s easy to see why: the species has attractive dark-green foliage year-round and bears red berry-like cones (a warning: these fruits are highly toxic to humans). Its dense growth habit allows it to be sheared into shapes if desired.
But we have a native North American yew, the Canada yew or T. canadensis, which is equally handsome. Sometimes inaccurately called the ground hemlock, this species once grew underneath most of our northern forests. Why the past tense? Yews are the favorite wintertime food of white-tailed deer, and they were eaten to oblivion in most locations as deer expanded their population and range. In the Arboretum, we must protect our yew collection with special fencing every winter.
A good booklet for basic information about our native conifers (and other trees as well) is “Forest Trees of Wisconsin,” published in 2004 by the Wisconsin Department of Natural Resources, Division of Forestry.
I hope for more hospitable weather conditions for my next tour!