Every person who has spent even a little bit of time in Pennsylvania’s forests knows what mountain laurel is. Hikers are familiar with it as it impinges on trails and seems to reach out and grab at packs and clothing. Hunters are familiar with it for many of the same reasons and its ability to hide game. Tourists flock to areas where it is prevalent to see it in bloom. And wildland firefighters are familiar with it for not only its propensity to burn, but also for its thick matted roots that resist line building. It is a pretty, but not fragrant flower that blooms in May and June. It is a wonderous event to visit a forest when the laurel is in full bloom. The town of Wellsboro even has a festival “The Laurel Festival” in June to celebrate the plant, complete with a Laurel Queen, parade and all the other events found in small-town festivals of that sort. It is so popular in Pennsylvania that 84 out of 9835 small watersheds have ‘Laurel’ in their name (second only to Mill at 121). There are even 18 places named in the Pennsylvania Gazetteer referring to Laurel.
Mountain Laurel (Kalmia latifolia) is sometimes referred to as calico-bush, or spoonwood. It is a broad leaf shrub that retains its leaves throughout the winter. It is a member of the heather family, Ericaceae, that is native to the eastern United States. The family of plants contains many common shrubs including huckleberries, blueberries, azaleas, cranberries and rhododendron. It can be found throughout the Appalachian Mountains from Maine to Florida and west to Indiana. Mountain Laurel is sometimes erroneously called Sheep Laurel, however sheep laurel is recognized as a distinctive species Kalmia angustifolia. The easiest way for a non-botanist to identify the two species is during the bloom. Mountain Laurel has light pink flowers and Sheep Laurel has darker, magenta blooms. The two species may be found in proximity to each other.
Mountain Laurel is the State Flower of Pennsylvania. (It is also the state symbol of Connecticut.) In 1933 the Pennsylvania General Assembly in a fit of indifference could not decide on a state flower. Some legislators favored the Pink Azalea (Rhododendron periclymenoides), others favored the Mountain Laurel. Compromise apparently was not an option. They passed two bills, one naming Mountain Laurel as the state flower, the other bill named the Pink Azalea as the state flower. Then they sent both bills to Governor Gifford Pinchot (a trained forester) and essentially said to him, “Pick one ya like!” Some accounts say that Gifford did not make the choice, but rather passed the decision on to his wife Cornelia. Whoever made the decision, Mountain Laurel became the State Flower of Pennsylvania on May 5, 1933.
WARNING: POISONOUS PARTS: All parts. Highly Toxic, Maybe Be Fatal if Eaten!
If for some strange reason you happen to ingest Mountain Laurel, you should know that symptoms. They include: salivation, watering of eyes and nose, slow pulse, nausea, vomiting, sweating, abdominal pain, headache, tingling of skin, lack of coordination, convulsions, and paralysis. It is an Andromedotoxin, a toxic compound C31H50O10 found in members of the heath family (Ericaceae). Honey made from the blooms of the plant can also impart the poisoning. In short if you eat Mountain Laurel it is going to mess you up.
Mountain Laurel is a heavy, hard and strong wood, but it is somewhat brittle. It has yellow sapwood and a yellow-brown heartwood with red spots. It has a green weight of 63 lbs/ft3. By comparison White Oak is 47 lb/ft3, Eastern White Pine is 22 – 31 lbs/ft3, and Eastern Hemlock is 50 lbs/ft3 when green.
The Janka hardness test measures the resistance of a sample of wood to denting and wear. It measures the force required to embed an 11.28-millimeter (0.444 in) diameter steel ball halfway into a sample of wood. This method leaves a hemispherical indentation with an area of 200 mm2. the measurement is in pounds-force (lbf). The rating for Mountain Laurel is 1,790 lbf., White Oak is 1,360 lbf., White Pine is 380 lbf., and Eastern Hemlock is 500 lbf.
The wood has been used for utensils (hence the nickname Spoonwood) furniture, bowls and other household goods as well as ornamental wreaths and roping. Until the 1960s, when man-made materials became widely used, the Mountain Laurel furnished root burls that could be substituted for expensive imported briar in the making of smoking-pipe bowls. The wood of these burls was far heavier, harder, and denser than that in the tree above ground, making it slow to burn from smoldering tobacco. Laurel briar is said to be inferior to the imported variety, but it still works for pipe bowls.
An “Old Hunter’s Tale” is that you will only find Mountain Laurel growing on the north side of the mountain. That’s pretty much false. If you use that as a guide to help you find your way out of the woods there is a good chance you will be spending the night in the woods, probably in a laurel thicket.
Mountain Laurel is usually an understory plant. During the past 100 years Mountain Laurel has spread and grown pervasively. After the Pennsylvania forests
were turned into the “Pennsylvania Desert” at the beginning of the Twentieth Century, Mountain Laurel had been subjected to fire, and destruction from timber harvesting. The regrowth of the forests into the infamous “red brush” kept the laurel from being able to compete and its growth was stunted. As the middle of the century arrived the forest canopy reached above the maximum height of the laurel, and space became available for it to begin to grow with abandon. Destruction of the canopy by the oak leaf roller, gypsy moth and other forest pests allowed additional light to reach the laurel permitting it to grow and exclude other plants, notably trees. While the plant is poisonous to humans, it seems to have little effect on white tail deer, who will browse it as a food of “last resort.” As a result, Mountain Laurel is not prone to overbrowsing by deer. It does, however make excellent cover for game. Many a young or novice hunter earned his stripes by following the directive to “Go through that laurel patch over there and kick something out.”
Mountain Laurel will burn hot and fast, due to the waxy leaves and relatively dry thin branches and stems. However, it will survive, and in many cases thrive after a fire. The plant grows reproductive rhizomes some up to 30 inches into the soil, where they are isolated from even the most drastic fire effects. Some prescribed fires have shown that Mountain Laurel will re-establish itself quickly after a fire and outgrow laurel in unburned areas in as little as 8 or 9 years. Sometimes in areas where canopy mortality has been the greatest due to fire the Mountain Laurel will grow best.
Mountain Laurel has matted roots and will grow over and among loose rocks. Trying to cut a fire line through a patch of laurel, even with modern mechanized machinery is a difficult task. In drought conditions fire can travel along the roots and rhizomes deep underground, beneath a fire line cut to mineral soil, and cause fire to break out across the line.
In some forests, prescribed fire is being utilized to thin if not outright kill Mountain Laurel, but like the hardy Pennsylvanians who settled in the forests where the laurel blooms, it is here to stay.