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Published In: Species Plantarum 1: 147. 1753. (1 May 1753) (Sp. Pl.) Name publication detailView in BotanicusView in Biodiversity Heritage Library

Project Name Data (Last Modified On 9/1/2017)
Acceptance : Accepted
Project Data     (Last Modified On 7/9/2009)
Status: Native


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8. Lysimachia thyrsiflora L. (tufted loosestrife, swamp loosestrife)

Naumbergia thyrsiflora (L.) Rchb.

Pl. 510 c–e; Map 2328

Plants with usually elongate, relatively stout, stoloniferous rhizomes. Stems 30–80 cm long, relatively stout (3–7 mm in diameter at the base), erect or strongly ascending, not rooting at the nodes, unbranched or occasionally with 1 or few branches toward the tip, not developing bulbils in the leaf axils, glabrous, but with scattered, glandular dots and lines. Lower stem leaves reduced to small scales, these sessile, ovate, grading into the main leaves near the midpoint of the stem. Main stem leaves opposite or rarely in whorls of 3, sessile or nearly so. Leaf blades (above the stem midpoint) 4–12 cm long, 0.7–2.0 cm wide, narrowly lanceolate to narrowly oblong-elliptic or narrowly oblanceolate, variously angled or tapered at the base, sometimes more or less truncate and slightly clasping the stem, angled or somewhat tapered to a sharply pointed tip, the margins entire or slightly and finely wavy, usually also with scattered, crinkly, multicellular hairs, often minutely curled-under, the surfaces with dark purple to black gland-dots or punctations, the upper surface green to dark green, glabrous, the undersurface lighter green, sometimes slightly glaucous, with sparse to moderate, crinkly, multicellular hairs along the main veins; secondary veins usually evident but often faint. Inflorescences axillary from the median leaf axils, 1 to several, of short, dense, ovoid, spikelike racemes with numerous flowers, these long-stalked (1.5–5.5 cm), the individual flower stalks 0.1–0.4 cm long, glabrous, but gland-dotted. Calyces 5–7-lobed, the lobes 2–3 mm long, narrowly lanceolate-triangular to lanceolate, with glandular dots and short lines, with 1–3 faint veins (the midvein sometimes slightly thickened). Corollas 5–7-lobed, the lobes 4–6 mm long, linear, angled to a bluntly or sharply pointed tip, the margins entire, yellow, glabrous and lacking reddish markings on the upper surface toward the base, however both surfaces with reddish purple to nearly black, short lines. Stamens slightly longer than the corollas, appearing exserted at flowering, the filaments 4.5–6.0 mm long, not fused into a tube basally. Staminodes absent. Styles 5–7 mm long. Fruits 2–4 mm long, more or less globose, the surface gland-dotted. Seeds few, 1.2–1.5 mm long, irregularly elliptic, oblong, or rhombic in outline, triangular in cross-section, dark brown. 2n=54. May–July.

Uncommon in the northern half of the state, mostly in counties adjoining the big rivers (northern U.S. [including Alaska] south to California and West Virginia; Europe, Asia). Marshes, fens, and bottomland prairies.

This distinctive species is easily recognized by the dense, ovoid inflorescences borne on long stalks from the axils of the median leaves, the exserted stamens, and the black-dotted stems, leaves, flowers, and fruits.



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