Veiny Meadow-rue is a native, erect, perennial spring plant of the woodland areas; the stems can be 1 to 3-1/2 feet in height, 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.
NOTE: Veiny Meadow-rue is known to hybridize with Tall Meadow rue and the plants in the Garden may show some characteristics of that.
The leaves are both basal and stem, and compound. There are 1 to 3 stem leaves, long stalked, 3 to 4 times 3-parted. Leaves at the base of the panicle will be without stalks. Each branch of the compound leaf has 3 to 5 thin leaflets that have 3 to 5 rounded lobes at the apex; these lobes usually have crenations. 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 20 mm wide. Both the leaflets and the stalk are hairless except that the leaflet underside may have glandular hair.
The inflorescence is an elongated panicle composed of narrow dense lateral umbels at the top of the flowering stem.
Flowers: Veiny Meadow-rue is usually dioecious, that is, plants have either male or female flowers but not both. The male flowers are 4 to 5 parted, with greenish to white oblong sepals. Sepals fall away early, there are no petals. Stamens number 10 or more and droop with the filament and anthers of the stamens longer than the sepals. Filaments are colored yellow to red, not white - the whole flower looks like a long drooping collection of stamens. The female flowers are held more erect, have pinkish to greenish-white sepals and numerous whitish flattened styles with yellowish stigmas. In the Thalictrum species the stigma extends down the side of the style. Flowers and leaves form at about the same time. Flowers are wind pollinated.
Seed: Fertile flowers produce an erect to spreading achene, elliptic-oblong in shape, dry, with a strongly curved body. They are strongly veined (ribbed) on the upper surface, with a very short stipe of 0.1 to 0.3 mm length (small stalk). The beak (1.5 to 2.5 mm long) includes part of the style. The achene body is 3 to 6 mm long. The veins are not reticulate but more parallel. Seeds require 60 days of cold stratification for germination.
Habitat: Veiny Meadow-rue grows from a horizontal rhizomatous root system, reproducing by seed and by spreading of the rhizomes. 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-mesic 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, venulosum, is from "venosum", referring to the prominent veining. The author name for the plant classification - ‘Trel’ refers to William Trelease (1857-1945), American botanist, entomologist and educator. He held teaching position in Botany at Harvard, University of Wisconsin, Johns Hopkins and Washington University in St. Louis and the University of Illinois. First president of the Botanical Society of American in 1894. Director of the Missouri Botanical Garden 1889-1912. 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 Veiny 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 with crenations of Veiny Meadow-rue. Veiny Meadow-rue. T. dioicum, Early Meadow Rue is the most difficult to distinguish, because the main difference is in the achene which has a slightly longer beak and the achene body is straight, not distinctly incurved. Also, the leaflets typically have only 3 to 12 rounded lobes but some of these may be found on T. venulosum 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: A section of the inflorescence. Drawing 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: Stages of stem development. 1st photo - the developing cluster of flower and leaf buds. 2nd photo - the leaves beginning to unfold. 3rd photo - mature stem with remants of the leaf sheath.
Below: One section of the compound leaf. Leaflets are highly variable in shape as can be seen here.
Below: Leaf upper and underside.
Below: A small cluster of staminate flowers with reddish anthers.
Notes: Veiny Meadow-rue is not listed in any of Eloise Butler's Garden Log notes nor was it listed on Martha Crone's 1951 Garden census, but from the density of plants in the Woodland Garden, it has been there for some time. Almost all those plants are staminate. Veiny Meadow-rue is native widely scattered parts of Minnesota. It has been surveyed in only 18 of the 87 counties. It is a northern plant, found in North America North of a line from Oregon east to Minnesota, Pennsylvania and New England, excepting some of the Canadian Maritime Provinces.
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 Wild Flower Garden, Inc. Text and photos are by G. D. Bebeau unless otherwise credited. "www.friendsofthewildflowergarden.org"