Eastern Hemlock is a native evergreen with a straight trunk, a conical crown of long slender horizontal somewhat drooping branches. It grows 60 to 70 feet feet high. The tree's leader is often slender, curved and drooping.
Bark is gray-brown and smooth when young turning to a cinnamon brown with thick furrowed scaly ridges forming flat plates.
Twigs are slender, yellow-brown to gray-brown in color, with dense fine hair. Buds are tiny.
Leaves: The needles are 3/8 to 3/4 inch long, flat and flexible with rounded tips - NOT stiff and pointed like White Spruce - very short stalks (no more than 1/2 the width of the needle), and abruptly narrowed peg-like bases. They appear to be in two rows in a single plane; they are dark green to shiny yellow-green above with 2 narrow white bands below (stomatal bands). Edges may have tiny teeth.
Flowers: The tree is monoecious, that is, male and female flowers are separate on the same tree. Male flowers are small, round yellow cone shapes near the ends of branches. These male cones have globular pollen packets and are mounted on a short green stalk. The female flowers are small light-green ovoid shapes at the branch tips, forming, after pollination, ovoid light brown cones, about 3/4 inch long that hang from the branches. These are soft and flexible and have rounded scales with rounded smooth margins and mature in the fall.
Fruit: Female cones are wind pollinated in the Spring and mature in August and September. Starting in October seed is dispersed by wind. Seeds are paired with elongated wings. Cone scales are not widely spread at dispersion and close during wet weather. Seed production begins around 15 to 20 years of age. Unlike White Spruce, seed cones occur every year.
Habitat: Eastern Hemlock grows in cool moist acidic soil with partial shade. The species is very shade tolerant and actually requires shade for establishment. It is a dominant species but slow growing and long-lived with a shallow widespread root system that is susceptible to overthrow by wind. Trees as old as 800 years have been located. The species will regenerate by seed but only in areas not subject to deer browsing. The main pest is the Asian Hemlock woolly adelgid, which can cause tree death after an infestation.
Names: The tongue twisting genus name, Tsuga, is actually from the Japanese name for the hemlocks of Japan. The species canadensis, means 'of Canada' where the tree was first typed. The author names for the plant classification are: First to classify, using the name Pinus canadensis. in 1753 was ''(L.)' which is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was amended by ‘Carrière’ which is for Élie-Able Carrière (1818-1896), French botanist, authority on conifers, who published the description in Traité Général des Conifères in 1855. Two centuries ago the tree was sometimes called Hemlock Spruce and sometimes identified as Abies canadensis but that is not an accepted name today.
Above: 1st photo - The hemlock Grove at Eloise Butler Wildflower Garden. For a summer view see the photo far below. 2nd photo - Bark turns from smooth on young stems to a cinnamon brown with thick furrowed scaly ridges forming flat plates on older trunks. 3rd photo - The needles have very short stalks and appear to be in two rows in a single plane and have 2 narrow white stomatal bands.
Below: 1st photo - Male flowers are small, round yellow cone shapes, that elongate to open the pollen sacs. 2nd photo - Female flowers start as light green cone shapes that turn into brown cones (3rd photo) after pollination and remain soft and flexible until seeds release in the fall.
Below: 1st photo - The male cones have opened revealing the pollen sacs. 2nd photo - The needles are soft and flexible with rounded tips.
Below: The grove of old Hemlocks at the North end of the Woodland Garden.
Notes: Eastern Hemlock is not indigenous to the Garden. Eloise Butler planted the first ones in Sept. 1911 - plants obtained from the Park Board Nursery, and again on May 28, 1914. On that date she recorded planting 28 Hemlocks and these are probably the oldest southern most remaining stand in the state and this stand near the back gate contains the largest known Eastern Hemlock in Minneapolis which is now on the Minneapolis Heritage Tree List for its "champion size". This tree is 80 feet high with a circumference of 84 inches. A second tree on the east path between Guidebook stations 16 and 17 is on that list for its "significant" size", it being 80 feet high and 69 inches in circumference.
Tsuga canadensis is the only species of Tsuga found in Minnesota. Gardener Cary George planted 15 new 2-foot trees in 1989. Eastern Hemlock is found in North America in the eastern 1/3, from Ontario and Minnesota eastward to the coast and into the southern states except for Florida.
Eloise Butler wrote this in 1914 about her planting of the Hemlocks: "Hemlock has not been listed among Minnesotan plants; but it has sneaked in, contrary to rule, with the idea that it may sometime break across the Wisconsin border. In order that the face of nature may be changed as little as possible in our trained wilderness, only a few specimens each of the state flora not indigenous to the Garden are admitted."
Endangered: Minnesota is at the far western edge of the range with a native population only known from Pine county. There were previous populations in Carlton and St. Louis Counties but those were mostly logged off and most of the remaining trees succumbed to forest fires and the rest died off. The MN DNR states there are only about 50 mature trees remaining in the wild. Only recently has the tree been listed as of "Special Concern" and in August 2013 was advanced to "Endangered" status. The population in the Garden and the younger population at the MN Landscape Arboretum is therefore of special importance. There are a few other landscape specimens known - one large tree on private land in Washington County for example. The National Champion Eastern Hemlock is in Macon NC measuring 159 feet high, 45 foot crown spread, 192 inches in circumference and scoring 382 points.
Uses: The wood of Eastern Hemlock is brittle and full of knots, thus not valuable for anything but rough wood needs. An extract of Hemlock bark was once a commercial source of tannin for the production of leather and that use led to the destruction of many mature stands of the tree. Other than the bark, the remainder was discarded. Tea was said to be made from the leafy twigs.
In his important 3-volume work, The North American Sylva of 1817-19, Francois Michaux adds considerable detail to the above: "Unhappily the properties of its wood are such as to give this species only a secondary importance, notwithstanding its abundant diffusion; it is the least valuable in this respect of all the large resinous trees of North America. But the regret which we should experience to see it occupying so extensively the place of more useful species is forbidden by a property of its bark inestimable to the country where it grows, that of being applicable in tanning.
It is taken from the tree in the month of June, and half the epidermis is shaved off with a plane before it is thrown into the mill. From the District of Maine it is exported to Boston, Providence, etc., and is almost exclusively employed in the tan-yards. Its deep red colour is imparted to the leather, and I have been informed by tanners that it is inferior to Oak bark, but that the two species united are better than either of them alone."(Ref. #26d)
References: Plant characteristics are generally from sources 1A, 32, W2, W3, W7 & W8 plus others as specifically applied. Distribution principally from W1, W2 and 28C. Planting history generally from 1, 4 & 4a. Other sources by specific reference. See Reference List for details.
Identification booklet for most of the flowering forbs and small flowering shrubs of the Eloise Butler Wildflower Garden. Details Here.
Friends of the Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"