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.