Tufted Loosestrife is an erect native perennial of swamps, bogs and marshes that grows from 1 to 2-1/2 feet tall on unbranched stems that are green to purplish-red, and sometimes slightly hairy in the upper half. There can be scale-like leaves near the base of the stem.
The leaves are lance-like, opposite in pairs, from 2 to 4 inches long and stalkless. Margins are smooth, the surface dotted.
The inflorescence consists of structures called a thyrse that arise from the middle stem leaf axils. A thyrse is a compact branching inflorescence like the flower cluster of the lilac with a central stem for the flowers but with short side stalks that actually hold the flower clusters. The entire structure is contracted and in the case of this species it almost resembles an egg shape on a short 1/2 to 2 inch stalk.
The flowers are small, bisexual, about 1/3 inch wide with a yellow funnelform corolla with 5 to 7 lobes (sometimes 9) spread when open and are streaked or dotted with black or reddish-brown resin canals. The five stamens with their yellow filaments and anthers are twice as long as the corolla and this helps create the ball-like effect of the thyrse. The style single and is greenish-yellow and also protrudes. Staminodes (false stamens) are absent. The corolla is twice the length of the green calyx which also has 5 to 7 (9) lobes and is also streaked or dotted with resin canals.
Seed: Mature flowers produce a small seed capsule containing several seeds that are shaken loose when mature by wind action on the stem. Seeds are very small, need light for germination and also at least 60 days of cold stratification.
Habitat: Tufted Loosestrife grows in wet soils of marshes, bogs, and shallow water areas from a rhizomatous root system that is quite shallow, sometimes right at the surface. It likes wet feet and full sun.
Names: Tufted Loosestrife was formerly in the Primrose (Primulaceae) family. Details of that change are given at the bottom of the page. The genus name Lysimachia is from the Greek for either king Lysimachus or from lysis meaning "a release from" and mache is for "strife". The legend is that Lysimachus, king of Sicily, was walking through a field. A bull chased him. He grabbed a loosestrife plant, waved it in front of the bull and it calmed the bull. In general then, both the common and the generic name refers to a supposed power to soothe animals or "loose" them of their "strife". The species, thyrsiflora, refers to the flower cluster being in the form of a thyrse - a contracted panicle form. 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.
Comparisons: This species is very unique and should not be confusing with any other species in a marsh environment.
Above: The upper stem section of a plant showing the form 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: 1st photo - The flower thyrse. Note the length of the stamens. 2nd photo - The leaf structure, showing the thyrses springing from the center leaf axils.
Below: 1st photo - The yellow-green calyx has 5 - 7 (9) lobes, same as the number of petals. The sepal lobes are no more than 1/2 the lenght of the petals. 2nd photo - Mature flowers produce a small seed capsule containing several dry seeds that are shaken loose when mature by wind action on the stem. In the photo the capsules have formed with the dry style remaining but are not yet dry and opened. The shape of the egg-shaped thyrse is clearly visible.
Below: 1st photo - The leaf underside can have some long but sparse, white hairs. 2nd photo - The lower stem can have a few scale-like leaves.
Notes: Tufted Loosestrife is native to all of North America except the states of the warmer U.S. south. In Minnesota it is found in all but 25 counties, the majority of the exceptions being in the southern part of the state. The plant is indigenous to the Wild Flower Garden. Eloise Butler noted it in her Garden log as in flower on June 4, 1910. Martha Crone listed it on her 1951 Garden Census.
Fourtern species of Lysimachia are of record in Minnesota per the U of M Herbarium as of 2018; several have not been collected in recent decades. Ten are still listed currently by the DNR on their plant surveys. Of those nine are native, one is introduced. The species of Lysimachia of record in the Garden, current and historical, are: Starflower, L. borealis; Fringed Loosestrife, Lysimachia ciliata; Moneywort, L. nummularia (the introduced species); Prairie Loosestrife, Lysimachia quadriflora; Whorled Loosestrife, L. quadrifolia; Swamp Candles, Lysimachia terrestis; Tufted Loosestrife, Lysimachia thyrsiflora; Garden Loosestrife, Lysimachia vulgaris.
Family Change: Some of the leading references have moved the species of Lysimachia from the Primrose (Primulaceae) family into a new plant family - Myrsinaceae, following the lead of Flora of North America (FNA) (Ref.#W-7). The U of M Checklist of the Vascular Flora of Minnesota (Ref.#28C) follows this classification. FNA states: “M. Källersjö et al. (2000) and B. Ståhl and A. A. Anderberg (2004) removed the nonrosette terrestrial members from Primulaceae in the broad sense and placed them in the Myrsinaceae, which are further distinguished by leaves and calyx often dotted with yellow or dark streaks, flowers with relatively shorter corolla tubes, seeds immersed in placentae, and wood devoid of rays or with multiseriate rays only.”
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"