Abies balsamea aka American Silver Fir

Abies balsamea, also known as balsam fir, is a North American fir tree native to eastern and central Canada as well as the northeastern United States. It is a dwarf cultivar with a low rounded mound shape and distinctively arranged dark green needle-like leaves that are whiteish beneath. Unlike other varieties, it does not produce cones. One of the most fascinating aspects of this species is its role in the fir wave phenomenon. This cyclic disturbance-regeneration cycle occurs when the death of overstory trees creates sunlight and warmth on the forest floor, allowing seedling regeneration. As these seedlings grow and become dominant canopy trees, the lack of light, cold temperatures, and poor nutrient availability lead to the death of the overstory trees. This cycle creates waves of growing, dying, and dead trees that sweep across the landscape. This phenomenon has been observed in various locations, including Baxter State Park in Maine, the Adirondack Mountains in New York, and the White Mountains in New Hampshire. Abies balsamea is a narrowly conical tree that can reach heights of 12-23 meters and diameters of 10-60 centimeters. Its bark is gray and thin, becoming broken into irregular brownish scales as it ages. The branches diverge from the trunk at right angles, with the lower branches often spreading and drooping. The twigs are mostly opposite, finely pubescent, and can be yellow grey-brown or green-brown in color. The brown to reddish-purple buds are either hidden by the leaves or exposed, and the scales are slightly pubescent. The tree's needles are arranged in a spiral or 1-ranked pattern, curving upwards on branchlets exposed to full sun. They are shiny dark green on the upper surface and green or grey-green below. The needles have a flat cross-section, grooved above and keeled below, with stomata in 0-4 rows at midleaf above and more numerous toward the apex. The base of the needles is twisted, and they have a pinelike odor due to ß-pinene. The apex of the needles is slightly notched to pointed, and resin canals are large and located midway between the abaxial and adaxial epidermal layers. The male cones of Abies balsamea are 15mm long and can be red, purplish, bluish, greenish, or orange at pollination. The female cones are resinous, sessile, and have a round to obtuse apex. They are cylindric to broadly ovoid in shape, measuring 4-10 cm in length and 1.5-3.75 cm in width. The color of the cones varies from blue-grey-green or purple to grey-brown or violet-brown. The scales are finely pubescent, and the bracts may be included or exserted and reflexed over the scales. The seeds of this species are triangular, with a brown body and a wing that is about twice as long, brown-purple in color. The cotyledons number around four. The chromosome count for Abies balsamea is 2n=24.