The oldest public wildflower garden in the United States
Early Meadow-rue (Quicksilver Weed)
Thalictrum dioicum L.
Spring to Late Spring Flowering
Early Meadow-rue is a native, erect, perennial spring plant of the woodland areas; the stems can be two or more feet in height, green to purplish-green in color, slightly angled and may have a whitish cast. There is the remnant of a protective sheath below where the stem branches into the flowering panicle.
The leaves are compound, 1 to 4 times 3-parted. Each branch of the compound leaf has 3 to 5 thin long-stalked leaflets that have 3 to 12 round-toothed lobes - the entire leaf can be up to a foot long. The leaflets are somewhat circular to kidney shape and can have bases that are wedge shaped. The largest leaflets are more than 15 mm wide. Both the leaflets and the stalk are hairless except that some plants may have glandular hair on the underside of the leaflet.
The inflorescence is an elongated panicle composed of lateral umbels at the top of the flowering stem.
Flowers: Early Meadow-rue is dioecious, that is, plants have either male (staminate) or female (pistillate) flowers but not both. The male flowers are 4 to 5 parted, with greenish to purplish oblong sepals that have white margins. Sepals fall away early, there are no petals. Stamens number 10 or more and droop with the yellow to greenish-yellow filaments; the anthers of the stamens are longer than the sepals - the whole flower looks like a long drooping collection of anthers and filaments. The female flowers are held more erect, have greenish-purple sepals and 1 to 16 whitish flattened pistils with light purple stigmas, each pistil connecting to an ovule (capable of producing a seed). In the Thalictrum genus the stigma extends down the side of the style. Flowers and leaves form at about the same time. Flowers are wind pollinated.
Seed: Fertile ovules produce an ovoid, dry, straight, strongly veined (ribbed) achene that is not laterally compressed and without a stipe (small stalk) or if with a stipe, it is very short. The beak (1.5 to 3 mm long) includes part of the style. The achene body is 3 to 5.5 mm long. The veins are not reticulate but more parallel. Seeds require 60 days of cold stratification for germination.
Habitat: Early Meadow-rue grows from a fibrous root system with a stout caudex, reproducing by seed. It is found in open woods and wood edges in sandy to loamy soil. It is quite shade tolerant (no full sun) and survives in moist to dry conditions. The plant dies back in late summer.
Names: The genus, Thalictrum, was originated from the Greek word 'thaliktron' by the Greek pharmacologist Dioscorides, who used it to describe plants with divided leaves. The species name, dioicum, is from the Greek meaning "of two houses", referring to the flower sexes being on different plants. The author name for the plant classification - 'L.' refers to Carl Linnaeus (1707-1778), Swedish botanist and the developer of the binomial nomenclature of modern taxonomy. In earlier times the Buttercup family was called the Crowfoot family.
Comparisons: There are only two species in the Garden and in Minnesota that will resemble Early Meadow-rue. One is the Tall Meadow Rue, Thalictrum dasycarpum, which grows much taller and in sunny locations and the leaves have several lobes at the tip, not the more numerous rounded teeth of Early Meadow-rue. Veiny Meadow-rue, T. venulosum, is the most difficult to distinguish, because the main difference is in the achene which has a slightly shorter beak and the achene body is not straight, but distinctly incurved with the front surface being 3 to 4 mm long. Also, the leaflets typically have only 3 to 5 rounded lobes but some of these may be found on T. dioicum also. Read Eloise Butler's notes below. Also a word of caution from Flora of North America; "Past treatments of Thalictrum have often emphasized leaf characters that are highly variable in most species; they are therefore of poor diagnostic value and not indicative of true relationships."
Above: 1st photo - The inflorescence. A plant with male flowers. 2nd photo - Detail of the flower bud cluster which forms with the new leaves.
Below: 1st photo - A panicle of female flowers. 2nd photo - Detail of the male flowers.
Below: Leaf structure - Each subbranch of the leaf on this plant has 3 leaflets.
Below: Comparison drawing of Early Meadow-rue (1st drawing) and Veiny Meadow-rue (2nd drawing). While there may be some differences in the number of lobes on the leaflets - fewer on Veiny) the key difference is in the achene. Early Meadow-rue achenes are straight and Veiny Meadow-rue achenes are distinctly incurved. Both drawings 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.
Notes: Early Meadow-rue is indigenous to the Garden area. Eloise Butler catalogued it on May 25, 1907. Susan Wilkins added plants in 2009, '11 and '12. It is native to the wooded parts of Minnesota in most counties except rarer in the dryer SW quadrant. It is found in the U.S. in the eastern half with the exception of the gulf coast and in Canadian in Ontario and Quebec.
Thalictrum is a large genus with almost 200 species worldwide, with 22 in North America. There are 5 species of the genus found in Minnesota, the three mentioned up above plus - T. revolutum, the waxy-leaf meadow-rue (from northern MN and is considered quite rare, if still present), and the fifth species is the Rue Anemone, T. thalictroides. Subspecies are not recognized.
Eloise Butler wrote: "It is not uncommon in Maying parties to hear the explanation, “Oh, what a pretty fern!” as the attention is attracted to the delicate many-branched leaf of the Early Meadow Rue, one of the crowfoot family. The leaf stalk of the meadow rue is branched four times into three divisions, so that it bears in all eighty-one leaflets. The leaf is as pleasing as that of a fern and adds an airy fern-like grace to a bouquet. Ferns, by the way, have three characters by which they may be distinguished from other plants - a coiled leaf-bud which unrolls at the base when the leaf expands, displaying a forked venation (a second peculiarity of the fern); and, later, some brown or yellowish dots usually on the under side in which are developed spores. Ferns have neither flowers nor seeds, while one individual of the Early Meadow Rue has a spray of tiny pollen-bearing flowers, and another the seed-producing flowers. These separated flowers are pollinated by the wind." Published May 28, 1911, Sunday Minneapolis Tribune. (Full Article) [NOTE: Her statement of the number of leaflets applies to a fully developed leaf. Plants will be seen with fewer leaflets.]
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 Wildflower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofeloisebutler.org"