New York Natural Heritage Program
Four-flowered Loosestrife
Lysimachia quadriflora Sims

General Description [-]
Lysimachia quadriflora is an erect, rhizomatous, perennial forb with 4-angled stems that grows (12-) 20 cm to 1 m tall. The leaves are opposite, entire, stiff, linear to narrowly lanceolate, and have revolute margins. They are 3.4 to 9 cm long by 0.2 to 0.6 cm wide, with 0.1 to 0.8 mm cilia at the leaf base near the nodes and have only one apparent vein. The flowers are borne singly or in whorls from the axils of the upper stem, on pedicels 0.5 to 2.8 cm long. The flowers are 5-parted with yellow petals that are sparsely streaked with brownish-violet (this is sometimes obscure) resin canals, and are 7 to 13 mm long and pointed, with stalked glands on their upper surfaces. The fruits are capsules 3.5 to 5 mm long and are typically glabrous (rarely with sparse stalked glands). (FNA 2010)

Best Life Stage for Proper Identification [-]
For positive identification of Lysimachia quadriflora the entire stem with intact mature flowers is best.

Similar Species [-]
A number of similar Lysimachia species occur in New York. Most differ from L. quadriflora by having punctate (minutely dotted) leaves. L. ciliata and L. hybrida have leaves that are not punctate, but they are typically broader with more evident lateral veins, and not revolute as are L. quadriflora's leaves (Haines 2011).

Hypericum canadense (Canada St John's wort) also may appear similar to L. quadiflora but can be distinguished by its numerous small flowers (3.2 to 6.3 mm wide), and shorter leaves (1.3 cm to 3.8 cm) with 1 to 3 veins.
Four-flowered Loosestrife Images
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The Best Time to See
Flowering typically begins in mid-June and continues through late July. Fruiting typically occurs beginning in mid-July with fruits persisting until late October.
Vegetative Flowering Fruiting
The time of year you would expect to find Four-flowered Loosestrife vegetative (blue shading), flowering (green shading) and fruiting (orange shading) in New York.