Balm of Gilead is the name used for a large native hybrid deciduous tree, growing to 80 feet in height and 2 to 3 feet in diameter with a pyramidal open crown. It has a straight trunk with ascending branches. This tree is similar in its characteristics to those of the subspecies balsamifera of P. balsamifera but it is a hybrid whose ancestry is not completely clear. See more details under "Names" below. Except for the stronger aromatics of the buds, the species are quite similar and the characteristics below are those of Balsam Poplar.
The bark is greenish-gray with light lenticels when young becoming gray and furrowed into long flat scaly ridges with age.
Twigs are somewhat stout, shiny reddish-brown with orange lenticels when young becoming grayish-brown by the third year. They can be very hairy to smooth. The winter buds are long (to 1 inch), curved and pointed and produce a fragrant yellowish resin of balsam odor in the spring. A crushed twig has a bitter aspirin taste.
Leaves are alternate, simple, ovate, 3 to 5 inches long and 1-1/2 to 3 inches wide, with a pointed tip and rounded, or slightly notched, base. They are mostly hairless with a shiny dark green above, whitish below, often with rusty color veins giving a blotchy orange appearance. Margins are finely wavy-toothed. The leaf stalks are round and long, (only occasionally a bit flattened) usually with two glands at the leaf base, but the glands may be absent.
The leaves will be slightly variable in shape and size on the same tree but the differences are less pronounced than in the other Populus species listed here because P. balsamifera is only weakly heterophyllous, that is, it has two types of leaves - those that are formed in the winter bud for early spring growth, known as preformed or early leaves and leaves produced later in the season known as neoformed leaves. The later leaves are slightly different in size and size of teeth and are the last to fall from the tree in Autumn but there will be fewer of the neoformed leaves because the species is weakly heterophyllous.
Flowers: Populus balsamifera is dioecious, that is male and female flowers occur on separate trees. Male (staminate) flowers have a cup shaped disc with 20 to 30 reddish stamens. These are bunched on a short curved catkin. Female (pistillate) flowers are in moderately dense 2 to 3 inch yellow-green drooping catkins. Female individual small flowers have a basal disc, a 2-chambered ovary, the pistil with 2 to 4 stigmata at the tip. Both flowers have a small bract whose upper edge is deeply cut but not hairy. The bract initially obscures the flowers. Both male and female catkins will usually contain (+ or -) 50 to 70 individual flowers. Flowers appear before the leaves and are wind pollinated.
Seed: After pollination, the female catkins elongate up to 4 inches in length and the fertilized flowers produce an egg-shaped light brown, 5/16 inch, pointed, hairless, 2 chamber seed capsule. Then the capsule splits into two and each chamber releases between 15 and 22 small seeds embedded in fine white cotton-like hair which are dispersed far and wide by the wind in early summer. Trees need to be about 8 years of age to produce seed. Seed germinates immediately.
Habitat: Balm of Gilead/Balsam Poplar grows mainly in moist riparian areas of the boreal and mountain forest. It is the northern most New World hardwood. It's root system is therefore shallow and spreading. It can re-generate from stumps, root sprouts and buried branches. It does not hybridize with either P. tremuloides or P. grandidentata.
Names: Flora of North America reports that the hybrid ancestry of the tree is suspected to have come from one of two sources: 1) it may have arose from a previous hybrid - Populus x jackii and P. x deltoides or 2), it may have came from Europe through hybridization of P. balsamifera and P. deltoides subsp. deltoides. The tree has more aromatic bud resin than the original species and was grown for collecting that resin for use in treating coughs and for salves and this led to the acquisition of the name Balm of Gilead which has old world and biblical references.
There are two spellings for the common name: Gilead and Giliad. You will find both in the references although almost all current authorities have dropped Balm of Gilead and use Balsam Poplar - both for the species and subspecies. In fact, Flora of North America does not even list subspecies any longer as they are considered more local ecotypes of the main species. Populus is the Latin name for 'poplar'. The species balsamifera means 'balsam bearing' referring to the aromatics of the tree. The author name for the plant classification, 'L.' is for Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy.
Comparisons: The bark of these trees is similar to others in the Populus genus, but this tree has much longer buds that are resinous and fragrant and more ovate leaves with rounded stalks. The other species have flattened leaf stalks, and finely toothed rounded leaves like P. tremuloides (Quaking Aspen) or the coarsely toothed leaves of P. grandidentata (Bigtooth Aspen). Compared to P. deltoides (Cottonwood), the leaf shape and twig shape are different.
Above: The tree has a straight trunk with ascending branches. Old bark (2nd photo) is furrowed into scaly ridges. Younger trunks (3rd photo) are grayish-green.
Below: 1st photo - The Balm of Gilead in Eloise Butler Wildflower Garden shows a similar form to the tree pictured above. 2nd photo - Young twigs are reddish brown with lenticels. Spring buds are curved and pointed.
Below: Leaves have a pointed tip and a rounded to slightly notched base. Dark green above, but sometimes taking on a rusty color in the veins giving a blotchy appearance as this young leaves have in the 2nd photo.
Below: Reproductive parts. 1st photo - an unfolding male flower catkin; 2nd photo - an unfolding female flower catkin; 3rd photo - fertilized female flowers forming seed capsules.
Below: A leaf comparison of the four Minnesota native species of Populus plus the introduced P. alba. Images not to scale.
Notes: Balm of Gilead (Balsam Poplar) is not indigenous to the Garden but Eloise Butler planted one in May 1909 on the base of the west hillside, the tree obtained from the Park Board Nursery and one in 1919 that she gathered at Lutsen, MN and planted near what is now the back gate of the Garden. Martha Crone also planted it in 1934. As the northernmost new world hardwood, this plant is found throughout Canada and in the U.S. not south of a line from Oregon to the east coast, generally not much south of the Great Lakes. There are scattered listings in other states that are probably from plantings. Within Minnesota it is found in the wild in almost all counties in the northern half of the state.
There are only four species of Populus that are native and commonly found in Minnesota: P. balsamifera, Balsam Poplar; P. deltoides subsp. monilifera, Plains Cottonwood; P. grandidentata, Bigtooth Aspen; and P. tremuloides, Quaking Aspen. Two others are reported: One is a native cross - P. X jackii, Jack's Cottonwood, which is usually sterile but as explained above is one possible for source for Balm of Gilead. [The DNR does not track county populations of it]; and the other is the introduced P. alba, White Poplar.
Eloise Butler wrote: "After a rain, we sniff the air with delight, saying, 'Oh yes, there’s a balm in Gilead!' as we pass a young balsam poplar that has been planted near one of the foot paths." From The Fragrance of the Wild Garden - Feb. 1915, unpublished.
Uses: Balm of Gilead buds are still used by a few folk practitioners if making first aid salves. Balsam Poplar wood is used for pulpwood, lumber and veneer, particle board and a high-grade paper.
Botanist Andre Michaux's son, Francois, in his North American Sylva of 1817-19 wrote (based on his father's notes): "This is one of the hardiest of the Poplars, though not of very rapid growth, except during the first three or four years in the nursery. In "Franklin's First Journey," it is stated that it is found as far north as the great Slave Lake, and that Mackenzie River has been named Riviere aux Liards, from the abundance of the tree in that quarter. "It also constituted," says Captain Franklin, "the greatest part of the drift-timber that we observed on the shores of the Arctic Sea."
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"