Plants of the Eloise Butler Wildflower Garden

Prairie Loosestrife is a native, erect, perennial forb, growing one to two feet high on green ridged stems that are either simple or with some branching near the top.

The leaves are linear and firm with a single main vein, deeply depressed on the upper surface. Margins are entire but can be curled back. Leaf surfaces are free of hair and glands. They are not stalked. Tips are pointed to bluntly rounded. Lower stem leaves are largest - up to 3 1/2 inches long but only 1/4 inch wide. They decrease in size in the upper sections of the plant. Side branches may have little whorls of leaves in the branch axils. There may be fine cilia at the stem nodes where the leaves grow, but not as pronounced as on Fringed Loosestrife.

The inflorescence is a single flower or a cluster of up to 4 flowers at the ends of the upper stems. When there are four they form a whorl and hence the alternate common name of Four-flower Loosestrife and the species name.

Flowers are on long stalks, nodding, up to 1 inch wide. However, not all of the four that compose a whorl are open at one time. The calyx has 5 green lanceolate sharply pointed sepals which appear between the five yellow petals of the corolla. The petals may have some brown streaking of resin canals as the outer surface is glandular. Petals have rounded tips with somewhat ragged margins and a distinct point. The widest part is just above the middle. The five stamens have light yellow filaments, darker yellow crescent shaped anthers which turn a reddish-brown at maturity. These are weakly united at their bases, are shorter than the petals and surround a single style. False Stamens are present but extremely short.

The fruit is a round capsule up to 5.5 mm in diameter, containing the numerous very small seeds which weigh 90,000 to the ounce. They need light and at least 60 days of cold stratification for germination, or simply leaving them on the ground to overwinter. The capsule has the remains of the sepals and the style attached.

 

Habitat: Prairie Loosestrife grows from a root system composed of slender rhizomes and a mass of fibrous roots. It is not an aggressive spreader. The plant prefers full sun, accepts partial shade, and needs wet to mesic soils. The plant is delicate so it can get overshadowed by larger neighbors.

Names: Prairie Loosestrife was formerly slotted into the Primrose family (Primulaceae), but the change to Myrsine is explained at the page bottom. 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". See notes below for more. The species name quadriflora, derived from quad for 'four' and flora, meaning 'flower' and thus means 'four-flowered', referring to the whorls of 4 flowers.

The author name for the plant classification of 1803 - ‘Sims’- is for John Sims (1749-1831), English botanist, first editor of Curtis’s Botanical Magazine, founding member of the Linnean Society, plant collector and author. While Sims original classification still holds, others tried to reclassify the species using the following names which are now not accepted: Steironema quadrifolium, Steironema longifolium, Lysimachia longifolia, L. revoluta, and Nummularia longifolia.

Comparisons: Several of our other native Loosestrifes have yellow corollas. Fringed Loosestrife, Lysimachia ciliata, has single flowers from the leaf axils and the corolla has a reddish eye in the center. Whorled Loosestrife, Lysimachia quadrifolia, has single flowers rising the leaf axils also, and there the leaves are broader and form a whorl of 4, hence the species name quadrifolia. Also, the corollas have the red eye and the open petals form more of a star pattern.