Nettles have small greenish flowers in branching clusters (cymes) that form from the upper leaf axils. Wood Nettle is a native erect perennial growing to 4 feet in height on green stems that are densely to sparsely covered with bristly stinging hairs and non-glandular non-stinging hairs. The plant can be invasive.
The leaves are alternate (the only such nettle), long-stalked, widely oval with coarse teeth. The very upper leaves can be opposite. The upper leaf surface is dark green with a main midrib vein, parallel laterals curving upward from the midrib and a crinkled looking pinnate vein pattern between them; the underside may have some longer stinging hair on the veins and is much paler in color due to fine surface hair. The leaf base can be rounded, truncate or wedge shaped, but without auricles.
The inflorescence consists of a panicle of long stalked clusters (cymes) of small female flowers (pistillate) in the upper leaf axils and clusters of male flowers (staminate) from the lower leaf axils. These are on the same plant and are held somewhat horizontal to the stem. The clusters have a creamy color before flower opening.
The sexes of the flowers are on separate panicles and the sepals and petals have combined into what are called tepals. Male flowers have 5 tepals, equal in length with 5 stamens placed opposite the tepals with their filaments slightly longer than the tepals. There is a false pistil in the center. The female flowers have 2 to 4 tepals in pairs, where the outer pair is either very short or entirely absent, the inner pair no longer than the ovary which is globose in shape. There is a long single style that has a feathery appearance from the stigma extending along the style.
Seed: Pollination is by the wind, resulting in the fertile female flowers producing a dark partially circular achene that is not enclosed in a capsule or entirely by the perianth of the flower.
Habitat: Wood Nettle grows from a rhizomatous root system with tuberous roots that allows it to spread vegetatively and form colonies. It prefers rich moist soils with partial sun in forests, along stream edges and marsh edges. At Eloise Butler you can find it along the back fence and on the wetland path and nearby is the Stinging Nettle.
Names: The genus name Laportea is named for Francois Louis de Laporte, Count of Castelnau, (1810-1880) a widely traveled Entomologist of the 19th century who traveled and collected in the United States between 1843 and 1847; and of course, canadensis is for "of Canada," where the plant was originally described. The common name “Nettle” may be from the Anglo-Saxon and Dutch word “Netel”, that work being derived from “Noedl”, a needle. There is also speculation that it comes from much older words that refer to the ability of the fibers to be sewn, a process used widely with the nettle species Urtica dioica.
The author names for the plant classification are: First to classify in 1753 using the name Urtica canadensis was '(L.)' which refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. His work was amended in 1854 by ‘Wedd.’, which refers to Hugh Algernon Weddell (1819-1877) English born French physician and botanist who specialized in South American flora.
Comparison: The Stinging Nettle, Urtica dioica, has opposite more lance-like leaves, is taller, and has a different looking flower cluster - more narrowly elongated and drooping. See comparison drawings below in the photos. The other Nettle in the Garden that resembles Wood Nettle is the stingless Canadian Clearweed, Pilea pumila.
Above: 1st & 2nd photos - The loosely branching cymes - male flowers below and female flowers above. 3rd photo - The bristly stem with both glandular stinging hair and non-glanudular non-stinging hair.
Below: 1st photo - The widely oval alternating leaf structure near the top of the plant. 2nd photo - The underside of the leaf showing the pale color and longer hairs on the veins.
Below: 1st photo - Detail of the flowers in a cyme with stinging hair on the main branches in early August. 2nd photo - The female flowers have a globose shaped ovary with a long single style.
Below: Wood Nettle. 1st photo shows the upper stem and inflorescence. Drawing shows female flower at LL and male flower at LR; from Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. 3 vols. Charles Scribner's Sons, New York.
Below: 1st photo - the mature female flowers in a cluster; 2nd photo - seeds forming, all at the end of August. Note that seeds are not enclosed in a capsule or entirely by the flower perianth.
Below: Comparison drawings of Wood Nettle and Stinging Nettle. Drawings ©Flora of North America.
Notes: Wood Nettle is indigenous to the Garden area. Eloise Butler catalogued it on Sept. 6, 1907. It is native to Minnesota and is found in most counties of the eastern 2/3rds of the state and scattered counties in the western 1/3. It is not as widely distributed in Minnesota or in the United States as the more common Stinging Nettle, Urtica dioica L., nor does it have the wealth of practical and medicinal history as does the Stinging Nettle - read about that here. In North America it is found in the eastern 2/3rds from the central plains eastward in the U. S. and from Saskatchewan eastward in Canada except in Newfoundland and Labrador. L. canadensis is the only species of Laportea found in Minnesota. It is host to the caterpillars of several butterflies.
Eloise Butler wrote in 1920: Laportea is a persistent spreader and sometimes gets the upper hand, busy as I am with many other things. In the fall I grub it out and plant something else in its place. Then I learn its encroaching ways. The roots are not very deep, but they are woven and knotted together into a dense mat that seems as hard as rock. From "Garden Principles - 1920."
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"